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HomeMy WebLinkAbout10-1966 • AV, 4 PLAN 41CKORY: Y` w e ~ ft~ F}t4 ` \ql y 1_ fly, 9 t 4 + ♦t A+ ji*il 1. S l 64 4 ~ t t 1l+~ a`.y4. 5. t \ ~ ♦ a+ f l `1 i. y L v if _Oh x ACR f- ~ ~ r * h'-~+` .y. t'r'y b. ~ (4 f ~ ~ ~ ~ # ~J ~ . _ n ` ".z '~wf+~` Ttw qV 'f J <rN 9 I t t We li V r 0 i 4, k4♦. K' 144, r TABLE OF Cf 4 1 5 - r} a_ ~£i3- _ - -o!*ta l+ Vill .kC i.Y ~ ~laf`•_' . Y~ _ 'E V~~S ~ a"~ VtA §~Fw~S.i~ Pit%6teeli 54 # t#b Est :I*rsd. A oc s S~4^ tt+? E f. YioC'1 r e. .iF < 'T, tSt,ii _i y; a:'''t .12-y} .#+`.s7• y T$?'files, rv g r i-LTG rsl ~f i kid ~,N'Yf.3 Fl+.. * r, ,5.. Y A.- i m,Y • I AV rind Wtldl jo 'i' f. s' b Y a sit ` » "d. t rri < s ru*c 9 a 4A 4 fit li k' $t rte: t r;§ , .5.7`Ty B' tis~' i i't"{ $ G~^ ? ? 3 ow!aWvkf- ZJA UY4 `F f'aE ~ - s~~ Z' s'tr S• q. T FT k "LAW, I )e ILI I all 0 SIATE:tSVID VC;%"N' 11V.ii AC%EEi%VTT betwcr.n Cie Detiton-1Iise Soil ntd?.a*~::_Cn_rervatinr. Dte.sr:Ct Local 0rj,.z,ti: a t10n 1)31worth Soil Ind Wnnter Crn crvntinn District Local Organization 1 Denton County Cc_ ,±psioncrn Court Local Crgnnization City of DantoniTe%as Local Organization of the State of Texas (hereinafter referred to as the Local Organisation) t and the } SOIL CONSERVATION SERVICE, UNITED STATES DEPARTMENT OF AGRICULTURE (hereinafter referred to as the Service) ' Whereas, the Soil Conservation Listricts have heretofore entered into a Flood Control Supplemental Memorandum of Understanding with th6 Soil Conserva- tion Service for aasistanco in constructing worksof improvement for prevention of floods in Hickory Creek Watershed, State of Texas, under the authority of the Flood Control Act of 1944 (58 Stat. 887); and t Whereas, the responsibility for carrying out a portion of the work of the united States Department of Agriculture on the watershed has been assigned by the Secretary of Agriculture to the Service; and ' Vaoreas, there has been developed through the cooperative efforts of the Local Organization and the Service a mutually satisfactory plan for works of ' improvement for the Kickorv Creek Watershed, State of Texas, hereinafter referred to as the watershed work plan, which plan is annexed to and made a part of this agreement; and Whereas, the County will benefit from installation of works of improvement through the reduction of damages to property, including county roads and bridgas located in the flood plain of the watershed; and r LPnereas, the City will benefit from installation of works of improvement through the reduction of damages to urban properties located in the flood plain of the watershed; if 't•,r, r:h2Y.:~(irC, 11 `:,c-.J r)i C11c 2'orC,':•)~ii~, C'413~SarAt ff~M3, t410 ;.nC'.1 ~J••.•rli:(']- t iot, 0;c S-1crotary of A;-z-iculturer di rough the 17Lrvice, hereby n:rrce en tt1C wovk pinn, r.nd feather jr,rco that the worka of improverrsnt as set forth is raid pion can be installed in r.bout el-ht years. It is n,ltually arrccd that in installing and operating and maintainino, tic wor.!s of 1;iprovcrrcnt cubstcntially in accordance with the terms, conditions, and stipulations provided for in the watershed work plan: 1. Tii; Local Organization will acquire witho+st cost to the A-cdcral S;nvcrn- r:cnt Such land, easements or ri<:hta-of-way as will be needed in connec- tion with the works of irnproversent. (Estimated Cost $541,800). The rcr- centares of this cost to ba b.rna by the Local Organization and the Service are as follows: Estimated Land, Easements, and Works of Local Rights-of-Way rovcment ,anization Service Cost (percent) (percent) (dollars) Floodwater Retarding S►.ructures Nos. 1 through 17 100.00 0 '5410800 1/ Includes $2,950 legal fees. 2. The Local Organization will acquire or provide assurance that land- owners or water users have acquired suc:1 water rights pursuant to State law as may be needed in the installation and operation of the works of improvement. 3. ►ne percentages of construction costs of structural measures to be paid by the Local Organization and by the Servirz are as follows: ' works of Local Estimated Jmprovcment Organization Service Construction Cost (percent) (percent) (dollars) F1oodF+a ter Retarding Stru^tures Nos. 1 ' through 17 0 100.00 1,136,180 r ncrccntav.cs of the cost for ins+rllatiriu services to be torn,e fry the local org::nization and the Scrviee are no follows: ' Esti.rieted of basal 7nsta11ctiun Z!ryr.r~r:ra'.nt Prnizatfon Service Service Cost (percent) (percent) (dollars) `r'loc,d,;::ter Retarding Strur_tures Ios. 1 throuf;h 17 0 lop 280, 360 5. The Service will award and adainister the contracts covering con- struction of all structural works of improvement. 6. %*he Local Organization will obtain agreements from owners of not less than 50% of the lend above each reservoir and floodwater retarding structure that they will carry out conservation farts or ranch plans on their land. 7. The Local Organization will provide assistance to landowners and ' operators to assure the installation of the land treatment measures shown in the watershed work plan. ' 8. The Local Organization will encourage landowners and operators to operate and maintain the land troatment measures for the protection and improvement of the watershed. 9. '11%e Local Organization will be responsible for the operation and r•.ainecnance of the structural works of improvement by actually per- forving the work or arranging for such work in accordance with agree- ' mt nt3 to be entered into prior to issuing invitations to bid for con- struction work. ' 10, 'Aa c costs shown in this agreement represent preliminary estimates. In finally determining the costa to be borne by the parties hereto, the actual costs incurred in the installation of works of improvement will be uoed. 11. This af;reenent does not constitute a financial document to serve as a basis for tine obligation of Federal funds, and financial and other assistance to be furnished by the Service in carrying out the watershe•' work plan is contingent on the appropriation of funds for this purpose. ' 12. T'he watershed work plan ,:,,y be amended or revised, and this agreement may bz modified or terminated, only by mutual agreement of the parties hereto. 13. No member of Congress, or resident commissioner, shall be ad-nittad to any share or part of this agreement, or to any benefit that may at ;re therefrom; but this provision shall not be construed to extend ci 1 L i ti,is ::rrcement if r.^Lti wt:li t: for its general bcne it. r 1•'3 . 'ii:, cond,iCtCd •:!.1 to in coraplleri.c wit@r all regr,ir( ,onts reapccting nonditcrimt~Ati..',n r.s contain:d in the Civil Rightc Act of 1964 and the revr.iations .-)f the Secretary of Agriculture (7 C.F.R. Sec. 15.1 - 15.13), which prcvide that no pcrron io the United catcc shall, on ti,-. frov:~~ .,r r1ce, color, or national origin, be c:ccluCc,3 fruim pnrticl,-, cion in, be denied the benafits of, or be s bj ected to discrimination under any activity receiving Federal financial assistance. 1 Dcnton•Wiuc* Soil and Water Conservation District Local Organization By Title ZZI r Date _ d T li,e si£nin;; of this agreement was authorized by a resolution of the govurning ' body of the Denton-Wise Soil and Water Conservation District Local Organization adopted at a meeting held on - / a 7 r ' (Se retary, Local Organizati n) Dato /.r 4. ~1 ' Dalworth Soil and Water Cong,~rvRtion District ],oCal Organiza on r TV / Title L%~*tw ~ .'~vt Date ' The sinning of this agreement was authorized by a resolution of the governing body of the Dalworth Soil and Water Conservation District Local Organization adopted at a meeting held on~ (Secretary, Local Organisation) i r Date - E of CwC i_ a'?tc<: 3t t hc1d on sc z 1 n ti . ) i tc i City of LO Ill OrLaniza ion BY .1 Ll~ l l _ Of C AU aj;rcc':.1C11C n '.-e!.olution of the j;GVcrnin;] hcdy Y.__ Local Oc-anization ~j ' adoptcc; at a ii;--utin. Il.alc; on I ^ r ~y (S_crc r , Local san:-ation) I y :uil Concczvztion Cervice United States ap.,,rtr.:ent o f A;;ricu turc ' Date I 1 r r WORK PLAN FOR WATERSHED PROTECTION AND FLOOD PREVENTION ' HICKORY CREEK WATERSHED Of the Trinity River Watershed Denton, Wise, Tarrant, and Dallas Counties, Texas 1 1 Plan Prepared and Works of Improvement to be Installed Under the Authority of the Flood Control Act of 1944 as Amended and Supplemented 1 Participating Agencies Denton-Wise Soil and Water Conservation District DalWorth Soil and Water Conservation District Denton County Commissioners Court ' City of Denton, Texas 1 ' Prepared By: Soil Conservation Service U. S. Department of Agriculture October 1966 1 ' 4 -2 1ose-a7 YNI 1[1 roof 0001e TIl 1111 WATERSHED WORK PLAN HICKORY CREEK WATERSHED Of the Trinity River Watershed Denton, Wise, Tarrant, and Dallas Counties, Texas October 1966 SUMMARY OF PLAN t Hickory Creek watershed, a tributary of the Trinity River, comprising an area of 145,600 acres or 227.5 square miles, is located in Denton, Wise, Tarrant, and Dallas Counties, Texas. All plann.:d structural measures are located in Denton County, Texas, where more than 95 percent of the drainage area of the watershed is located. The Denton-Wise Soil and Water Conservation District, Dalworth Soil and Water Conservation District, Denton County Commissioners Court, and the Denton City Council, local sponsoring organizations, propose installing a ' protect for watershed protection and flood prevention du-ing an 8-year period. The total installation cost is estimated to be $3,874,326. The share to be borne by other than Flood Prevention funds is $2,416,936. in addition, local interests will bear the entire cost of operation and main- tenance of structural measures estimated to be $1,760 annually. The :major land uses in the watershed are cropland, 36 percent; pastureland, t 46 percent; rangeland, 11 percent; and miscellaneous, 7 percent. All of the agricultural land is privately owned. ' The principal problem in the watershed is the frequent fA'.ooding of approxi- mately 6,912 acres of flood plain, excluding stream channels. An average of two floods occur annually, with more than 50 percent of the flood plain inundated on the average of twice each five years. The City of Denton has ' urban developments on 120 acres of the flood plain along the Pecan Creek tributary where frequent flooding occurs. The average annual floodwater damages without the project is estimated to be $67,109, including $27,100 in the urban area. In addition, sediment, scour, and indirect damages amount to $14,951 annually. Land treatment measures are being established through the leadership of the Denton-Wise and Dalworth Soil and Water Conservation Districts. Landowners and operators will be encouraged to accelerate the installation of those ' land treatment measures which will contrit+ute directly to watershed pro- tection, flood prevention, and sediment control. The cost of land treatment measures installed to date is $610,179. The work plan proposes the installa:ion of land treatment measures at an accel- erated rate for the 8-year period in the amount of $1,915,986. Of this l-:$04$ 3 -01 1 2 r amount, $40,850 is to be borne by Flood Prevention funds for accelerated technical assistance and $1,875,136 from other funds. ' Seventeen floodwater retarding structures will be installed at an estimated cost of $1,958,340. Of this amount, $1,416,540 will be borne by Flood Pre- vention funds and $541,800 from other funds. The sponsoring local organi- zations will furnish all needed land, easements, and rights-of-way for structural measures. It is expected that a major portion of the easements and rights-of-way will be donated fGr structural measures. If nezessary, ' the Denton County Commissioners Court vill use their rights of eminent domain to secure easements for floodwater retarding structure Sites 1 through 15, and the Denton City Council will use its rights to obtain ease- ments for the remaining structure Sites 16 and 17. These structural meas- ures will be installed during an 8-year period. Storage capacity was not planned in any of the structure sites for purposes other than sediment storage and floodwater detention. Eighty-five landowners and operators of 6,912 acres of flood plain land will benefit directly from the installation of this project. The average annual floodwater damage reduction benefits are estimated to be $52,376 with the project installed. In addition, flood plain scour, sediment, and indirect damage reductions wilt amount to $10,109 annually. The ratio of the total annual benefits of $90,879, resulting from installa- tion of structural works of improvement, to the annual cost of $65,640 is 1.4 to 1. Landowners and operators will operate and maintain all land treatment meas- ures installed in this watershed. Denton County Commissioners Court will operate and maintain floodwater retarding structure Sites 1 through 15 and the City of Denton, Texas will operate and maintain Sites 16 and 17. Monies for this purpose are available from general funds. DESCRIPTION OF THE WATERSHED Physical Data Hickory Creek watershed encompastes an area of 145,600 acres (227.5 square miles) and is locatei in Denton, Wise, Tarrant, and Dallas Counties. Denton, the county seat of Denton County, is the principal municipality in the watershed. Other towns included are Slidell, Krum, Ponder, Argyle, Lake Dallas, and Lewisville. Hickory Creek originates near the town of Slidell in Wise County and flaws in a southeasterly direction for 27 miles, emptying into Garza-Little Elm ' Reservoir. Some of the larger tributaries are North Hickory, Middle Hickory, South Hickory Creeks, Dry Branch, and Roark Creek. Pecan Creek, Prairie Branch, Timber Creek, and Baker's Branch are also located within ' the watershed boundaries. Pecan Creek flaws into Garza-Little Elm Reser- voir. Prairie Branch and Timber Creek confluence with the Elm Fork of the Trinity River below the reservoir. Baker's Branch flaws into Denton Creek ' 3 ' below Grapevine Dam. There are approximately 6,912 acres of flood plain in the watershed, including 1,600 acres of flood plain along the Elm Fork and ' Denton Creek. The watershed ranges in width from six to nine miles. Elevations range from approximately 1,000 feet above mean sea level along the northwestern ' divide near Slidell to 532 feet where Hickory Creek enters the flood con- trol pool of Garza-Little Elm Reservoir. ' Surface rocks in the tershed are of Cretaceous age and dip normally to the southeast at 40 feet per mile. The formations of the Lower Cretaceous (Comanche aeries) are ir. the Fredericksburg and Washita groups. The Upper Cretaceous (Gulf series) is represented by the Woodbine and Eagle Ford ' groups. The lowest unit of the Fredericksburg group occurring in the watershed is the f.;oodland formation. This formation is exposed along the watershed divide near Slidell and is composed of a hard, mss-ively bedded limestone which has an average thickness of approximately 50 !'eet. The upper unit of 1 the group is the Kiamichi formation. This formation consists of stratified and laminated clays with thin flagstone beds. The Washita group is exposed in a broad belt extending from Slidell south- easterly for about 18 miles to U. S. Highway 377. The strata have a total thickness of approximately 500 feet and form a rolling upland prairie. In- cluded in this group are marine shaly clays, marls, limestone, and sand- stones of the Duck Creek, Fort Worth, Denton, Weno, Pawpaw, Mainstreet, and Grayson formations. ' Rocks of the Pepper, Dexter, and Lewisville formations of the Woodbine group occur in the lower portion of the watershed. These formations are highly variable in composition and consist of crossbedded sandstones and laminated shaly clays forming gently rolling to hilly uplands. ' Shales of the Eagle Ford group are exposed in the lower extremities of the watershed near Lewisville. ' Soils of the Grand Prairie Land Resource Area are found in the upper 55 percent of the watershed. The principal soil series include Bolar, Burle- son, Crawford, Heiden, Lindy, Payne, Houston Black, Trinity, and Frio. These are predominantly deep to moderately deep, clays, silty clays, and clay loams. Subsoils are similar in texture to the topsoils and are moder- ately to very slowly permeable. Fertility levels generally are moderate ' and erosion is low to moderate. Soils of the Cross Timbers Land Resource Area are located in the central ' and later portions of the watershed. Fertility levels are generally low. Soils are uneroded to slightly eroded on the nearly level to gently sloping areas and Dlightly to moderately eroded on the steeper areas. Some soils are severely eroded on formerly cultivated fields. These areas have been converted to pastureland and erosion has greatly reduced. The major soil series include the Konawa, Doughtery, Stidham, Travis, Axtell, ~_:sass a-~~ ' 4 ' and Caley. These are predominantly fine sandy luams and loamy fine sands. Sandy clay loams, sandy clays, and heavy clays form the subsoils and are rapidly to very slowly permeable. Approximately 37 percent of the water- shed lies in this land resource area. The soil series of the Blackland Prairie Land Resoutce Area include the Houston Black, Heiden, Trinity, Gowen, Crockett, and Wilson. The textural range of the soils is comprised of clays, clay loams, and fine sandy loams. Subsoils are moderately to very slowly permeable and are composed of clays ' and clay loams. Fertility levels are moderate to high. They are limited to the extreme lower portions of the watershed near Lewisville and occupy eight percent of LLe drainage area. Land use in the watershed is estimated to be: Land Use Acres Percent Cropland 529300 36 Pastureland 67,176 45 Rangeland 150700 11 Miscellaneous 1/ 10,424 7 Total 145,604 100 ' li includes roads, highways, railroads, urban areas, stream channels, etc. ' The natural vegetation consists generally of a post oak and blackjack oak savannah in the Cross Timbers. The Grand Prairie and Blackland Prairies are true grass prairies with about a five percent cover of woody vegeta- tion such as live oak, elm, and hackberry. Some of the climax grasses are little bluestem, Indiangrass, big bluestem, sand lovegrass, switchgrass, and Virginia wild rye. Increasers are tall dropseed, hairy grams, silver ' bluestem, sideoats grama, Texas wintergrass, Scribner panicum, and woody plants. Vegetation that invades as a result of vveruse of rangeland in- cludes sand dropseed, splitbeard bluestem, threeawns, fall witchgrass, buffalograss, windmill grasses, Texas grama, mesquite, prickly pear, night- shades, sumac, and all annuals. Range sites within the watershed are Rolling Prairie, Deep Upland, Bottomland, Stony Hills, Sandy Loam, snd Sandy. The range condition classes of the watershed are as follows: Class Grand Prairie Cross Timbers Blackland Prairie (percent) (percent) (percent) Excellent 10 8 5 Good 30 30 25 Fair 40 42 45 Poor 20 20 25 Total 100 100 100 The hydrologic cover on pastureland and rangeland, ranging from poor to good, is classified mostly as fair. Cropland produces somewhat less 5 effective hydrologic cover, but conservation practices such as cover and green manure crops, crop residue use, terracing, and contour farming have been effective in reducing erosion, sediment, and flood damages. The mean annual precipitation of 31.56 inches, based on a 30-year record at Denton, Texas, is fairly well distributed throughout the year, with the greatest amounts of rainfall occurring in April and May. The minimum recorded rainfall was 18.49 inches in 1948 and the maximum was 58.35 inches in 1957. The mean annual temperature is 65 degrees. Temperatures ' range from a mean low of 34 in January to a mee.n high of 96 degrees in July. The normal growing season is 226 days. 1 Water for domestic and livestock uses in the rural areas is supplied largely by small ponds and shallow wells. Water for Denton is provided by wells and Garza-Little Elm [reservoir, while Lewisville, Slidell, Krum, e Ponder, Argyle, and Lake Dallas obtain water from wells. Economic Data Agricultural production constitutes an important part in the economy of this watershed. Farm units, in the watershed as a whole, average about 280 acres in size. More than half of the farms are operated by tenants. ' The livestock enterprise consists primarily of beef cattle, dairying, and sheep production. Cash crops grown in the watershed are oats, wheat, grain sorghums, hay, and small acreages of cotton. ' The flood plain formerly wag used for products.„ of cultivated crops, hay, and pasture. Because of frequent flooding, sediment, and erosion damages, most of the cultivated land has been diverted to hay crops and improved pastures. It is expected that more of the flood plain, once used for row crops, will be utilized for feed and hay production in connection with the growing livestock enterprises. Ownership trends indicate a decreasing number of farms with more acres per farm. The tenure trends are towa:d an increase in farm managers. Land value and farm size have been influenced by the proximity of the watershed to the metropolitan Dallas-Fort Worth area. The current market price of land ranges generally from $150 to $300 per acre, although there are some areas where these values are so high that the land cannot be economically used for agricultural production. Industries within the watershed include plants manufacturing bricks, ' business forms, clothing, flour, feed, highway signs, boats, trailers, and plastics. There are many businesses netted with water recreation. The transportation needs in the area are served by approximately 450 miles of roads, of which an estimated 150 miles are paved. These roads provide adequate access to all parts of the watershed. Four railroads transverse the watershed and ample loading facilities are available at Denton. The population of Denton County, in which more than 95 percent of the watershed is located, has increased from 47,432 in 1960 to 56,000 in 1965. 6 ' The 1960 census showed 1,863 farm families with a median family income of $6,370 per year. A large percent of the farmers and ranchers in the water- shed supplement their income with employment in the nearby Dallas-Fort Worth metropolitan area. Approximately 11 percent of the total income for Denton County is derived from agricultural operations. The City of Denton is a cultural center offering excellent educational and employment opportunities for the residents of the watershed and surround- ing area. North Texas State University and Texas Woman's University, with ' a combined enrollment of approximately 15,000 students, add to the commu- nity's economy. t The watershed area is well suited for recreational development and is readily accessible to the Dallas-Fort Worth metropolitan area. Denton, Dallas, Tarrant, and Wise Counties have not been designated as an area of underemployment under the Area Redevelopment or the Public Works and Economic Development Acts. ' Approximately 40 of the family type farms use one and one-half or more man-years of hired ls!,or. t Land Treatment Data The Soil Conservation Service work unit at Denton, Texas is assisting the Denton-Wise Soil and Water Conservation District which covers approxi- mately 95 percent of the watershed. The work units at Dallas and Fort Worth are assisting the Dalworth Soil and Water Conservation District in the remaining five percent of the area. Technical assistance has been provided to cooperators of the districts in preparing 360 basic soil and water conservation }Mans on 98,280 acres and in establishing and maintain- ing the planned land treatment measures. Current revisions are expected on 167 basic conservation plans during the installation of the project. Soil surveys are complete on 30,670 acres. The remaining area, 114,930 acres, is scheduled for survey during the early part of the project in- stallation period. More than 43 percent v: the land treatment practices needed on cropland have been appli^d. Needed land treatment practices have been applied on approximately 10 percent of the pastureland. A total of 75 percent of the needed land treatment will be established by tha end of the installation period. WATERSHED PROBLEMS Floodwater Damage There are 6,912 acres of flood plain land, excluding stream channels, in the Hickory Creek watershed. Of this amount, there are 4,279 acres of flood plain along Hickory Creek and its tributaries above the 10-year frequency pool of Garta-Little Elm Reservoir at (mean sea level) elevation 525.0. There are 599 acres of flood plain land along the Timber Creel: lateral, above its entrance at the bottomland common with the Elm Fork of the Trinity River. There are 434 acres of flood plain land along the Pecan 4-22040 J-~~ r 7 1 _ J mow. • he'd , ' IT....•Ay w r ' Rains of April and May 1957 resulted in extensive damage to crops and structures along the entire length of main stem Hickory Creek. Photo taken at Texas and Pacific railroad crossing south of Denton. Photo by Denton Record-Chronicle. r y. ilk IV, r ' Flash floods of 1957 caused extensive fence damage, adjacent fields suffered scour damage, sediment and debris were deposited in channels. Photo of tributary of hickory Creek. ' 4.21040 2-07 8 a! T. tit. f .`Qt v .r 4~ .r~I a~ ~,~`7~.t r 1 w' IM, Highway and railroad damage caused by floods of September 1962. Texas and Pacific Railroad in center of photo and U. S. Highway 377 in back- ground. Photo by Denton Record-Chronicle. r ' s-2804! 2-N 1 9 11 ! tom'. • n M 1 , s ~ s h { ~y ! P awl' v _ r err 10 1 ' r ~ k 01 off n J rti + A 1 ' Road and bridge damages typical to these shown occur frequently in all portions of the watershed. 1 10 Creek lateral, of which 120 acres are utilized in urban developments and 314 acres devoted to agricultural uses. Fifty-six acres of the agricul- tural land along Pecan Creek are located upstream from the urban area and 258 acres are downstream. The flood plain along Elm Fork, common to the Hickory Creek watershed, consists of 1,600 acres. The entire flood plain ' has been inundated by the runoff from the largest storm considered in the 20-year (1944 through 1963) evaluation series. During the 20-year period there were 8 major floods covering more than half the flood plain and 36 minor floods. More than 46 percent of the floods have occurred during the months of April, May, and June. This is the season when crops are at a critical stage of growth and are very ' susceptible to damage from floodwater. An average of two floods occur annually on the Hickory Creek watershed. Floods that inundate more than 50 percent of the flood plain occur on the average of twice in five years. ' The two largest floods occurred in 1957 and 1962. Runoff from the 1957 storm inundated the entire flood plain. Damage to county roads, State and Federal highways, bridges, and fences was extremely heavy. The average annual flood damages without the program of land treatment and structural measures are estimated to total $82,060. These include $15,129 ' of crop and pasture damage, $7,806 of other agricultural damage, and $17,074 of road and bridge damage. Urban damages average approximately $27,100 annually. Sediment, erosion, and indirect damages amount to $14,951 annually. ' At one time, about 80 percent of the flood plain was in cultivation. Fre- quent flooding has forced operators to retire all but about 25 percent to ' hay crops and improved pasture. Improved pastures are not beiatg managed for maximum use due to loss of fertilizers and seeds from flooding. Nox- ious weed seed are washed in on flood plain land and film deposits of sed- iment are left an grasses. Livestock will not graze until another rain falls and cleans the grass of this sediment. Attempts have been made by individual landowners to levee bottomlands, but these efforts, generally, have not proved to be satisfactory. Urban flood damages have been experienced in the City of Denton. Flooding in the past has caused extensive damage to approximately 150 private homes ' and 10 businesses. The CiLy of.Denton, Texas has installed a concrete lining along part of the channel of Pecan Creek through the urban area. It is estimated that the improved channel will carry the runoff from a storm expected to occur on the average of once every 10 years. Urban areas should be provided with a higher level of protection and additional flood prevention measures are needed. ' Erosion Damage Flood plain scour damage is generally low. This can be attributed to ' grassland which provides protective cover on a high percentage of the flood plain lands. The area of greatest damage occurs along a six mile section of Hickory Creek (Reach II, figure 5) extending two miles upstream ' 11 ' and four miles downstream from U. S. Highway 377. Flood plain scour dam- age by evaluation reach is as follows: ' Acres Damaged Percent Evaluation Reach 10 20 30 40 Total ' it VII, VIII NO DAMAGE II 37 119 13 13 182 III - 13 4 5 22 ' IV 41 51 - 92 V 5 5 VI - 78 9 - 87 ' IX 8 8 X 4 4 Total 37 268 77 18 400 t The estimated average annual damage by flood plain scour .d $3,232 (table 5). Channel entrenchment and lateral erosion are generally minor in the watershed, with the exception of the upper reaches of Timber Creek where these processes have been quite active. The estimated land loss by channel erosion in the watershed is leas than three acres annually. ' Erosion rates in the watershed range from low to moderate. Conversion of cropland to improved pastures and application of land treatment measures have signi'A cantly reduced erosion damage since 1950. This trend of con- verting cropland to pastureland has been particularly effective in reduc- ing erosion in the Cross Timbers portion of the watershed. ' Present annual erosion rates in the upland range from 4.4 to 13.2 tons per acre on cropland and from 1.0 to 2.2 tons per acre on rangeland and pastureland. The average annual erosion rate for the watershed under ' present conditions is 4.2 tons per acre. In the upland area, sheet ero- sion accounts for 92 percent and gully and streambank erosion for 8 per- cent of the annual soil loss. ' Sediment Damage Damage by overbank deposition is low. This results mainly from the low to ' moderate sediment production and the fine texture of the materials depos- ited. The most damaging deposition has occurred on the Timber Creek flood plain. Improved cover has resulted in a reduction in upland sediment ' sources of Timber Creek during the last 15 years and has permitted a high rate of recovery on the damaged flood plain. ' Modern sediment deposits are mainly clays and silts with lesser amounts of silty sands. Under present conditions, the productive capacity of 585 acres of flood plan is being reduced 5 to 30 percent, as follows: 4-2704! 2-!• 12 Acres Damaged _ ' Percent Evaluation Reach 5 10, :Q 30 Total it VII, VIII NO DAMAGE ' II 157 56 213 III 17 9 86 IV 79 30 - 109 V 20 - - - 20 ' V1 43 8 - 51 IX 30 30 8 - 41 25 10 76 Tonal 376 174 25 10 585 mn~ ' The average annual damage from sediment deposition on flood plain lands is estimated to be $1,434 (table 5). Stream channel aggradation is generally minor. Gravel deposits have re- duced channel capacities of North Hickory and South Hickory Creeks approxi- mately 10 percent. Aggradation also occurs in the middle reaches of ' Timber Creek where sand deposits have reduced channel capacities 10 to 29 percent. it is estimated that 130 acre-feet of sediment is being deposited annually ' in Garza-Little Elm Reservoir from Hickory Creek watershed. The annual damage to this reservoir by depletion of its capacity is estimated to be $2,825 (table 5). ' Problemb Relating to Water Management ' Problems relating to surface drainage and irrigation activity are insigni- ficant in the watershed. According to the sponsoring local organization, there is no known local interest at the present time in providing storage for irrigation in any of the structures. ' The towns of Lewisville, Slidell, Krum, Ponder, Argyle, and Lake Dallas obtain their water from wells. These towns are not interested in develop- ment of a multiple-purpose structure. The City of Denton obtains its water from wells and Garza-Little Elm Reser- voir. While acute water shortage is not a problem at the present time and plans have been made to assure adequate water for the immediate future, the City of Denton, cognizant of rapid growth and expansion, is vitally interested in any project that offers potential development of additional municipal and industrial water supplies. Rural water supplies are obtainel from shallow wells and ponds which ' furnish adequate amounts to satisi; daily needs. 4.!!040 a-0+ t r 13 r The towns in the watershed do not create a pollution problem at the present time. The City of Denton has a modern sewage treatment plant which can handle 2,000,000 gallons per day. Plans are underway to triple this capa- city by 1969. According to City officials, there are no industrial pollu- tion problems at present. Chemical pollutants such as insecticides are not used extensively in the watershed. There is no interest in the watershed to develop a water based recrea- tional facility. Garza-Little Elm Reservoir provides an excellent area ' for water based recreational activities. Farm ponds within the watershed provide a source for fishing. Fishing along the intermittent streams of the watershed is limited to small water holes. r PROJECTS OF OTHER AGENCIES r Garza-Little Elm Reservoir, completed by the U. S. Corps of Engineers in 1954, and into which th, major portion of Hickory Creek watershed drains, includes conservation storage for the municipalities of Denton and Dallas, Texas. r The planned works of improvement for Hickory Creek watershed will prolong the life of Garza-Little Elm Reservoir by reducing the rate of sedimenta- r tion. Structural and land treatment measures in this watershed wil' not produce any foreseeable detrimental effects to this or to any other pro- ject which may be developed in the future. There are no known plans for additional works of improvements for water resource development which would affect or be affected by the program in- 1 cluded in this work plan. ' BASIS FOR PROJECT FORMULATION ' Following a request for planning assistance, a reconnaissance of the water- shed was made by staff specialists of the watershed planning staff. Meet- ings were held with the local sponsoring organizations to discuss existing problems and to formulate the objectives of a watershed protection and r flood prevention project. Frequent flooding prevents intensive land use and causes damage to crops, pastures, and other agricultural properties. Urban damages have occurred frequently along the Pecan Creek tributary in ' the City of Canton. The following specific objectives were agreed to: ' 1. Establish land treatment measures during the project instal- lation period which contribute directly to watershed protection and flood prevention. r 2. Attain a reduction of 65 to 75 percent in average annual flood- water and mediment damages along Hickory Creek and its tribu- taries. ' ~_aaoee a-e~ 14 3. Obtain complete protection from the 100-year frequenzy storm in the urban area of Denton along the Pecan Creek tributary. Y Other objectives of the over-all watershed project are reduction of upland erosion and encouragement of owners to develop the structure sites as ' recreational areas. Recreational developments at sediment pools of flood- water retarding structures will provide landowners the opportunity to establish income producing enterprises. Alternate systems of structural measures were evaluated to obtain the most economical system. Land treatment measures and floodwater retarding struc- tures are the most feasible means of meeting project objectives. ' The opportunities for including storage capacities for purposes other than flood prevention were explained. Denton is the only city in the watershed ' interested in additional storage. It was determined that their future reeds for municipal water exceeds the storage permissible under the Flood Control Act. At the present time, Denton is obtaining water frc-.0 wells and Garza-Little Elm Reservoir. It was determined that a project for watershed protection and flood preven- tion meets local nee( s and that no other group or individual is interested ' in obtaining additional storage for other purposes. In the selection of floodwater retarding structure sites, consideration was given to locations which would provide the desired level of flood protec- tion. The location, size, number, and cost of structures were influenced by topographic and geologic conditions, existing roads, pipelines, power- lines, land use, and farmsteads. Alternate combinations of structural ' measures including stream channel improvement which would provide the de- sired level of flood protection were considered during the development of the work plan. The most efficient system was used to meet the project ' objectives. WORKS OF IMPROVEMENT TO BE INSTALLED ' Land Treatment Measures An effective conservation program based upon the use of each acre of agri- cultural land within its capabilities and its treatment in accordance with its needs, such as is now being carried out by the Denton-Wise and Dalworth Soil and Water Conservation Districts, is essential to a sound and continu- ing program of flood prevention in the watershed. Basic to the attainment of this objective is the establishment and maintenance of all applicable soil and water conservation and plant management practices. Emphasis will be placed on accelerating the establishment of land treatment practices which have a measurable effect on the reduction of floodwater and sediment damages (table 1). ' The extent of needed land treatment measures which have been applied to date within the project area represents an estimated expenditure by land- owners and operators of $610,179, excluding reimbursements from Agricultural ' 15 V e, 7- { }y ,1 + w jt~ i,. "The acreage of coastal bermudagrass is expanding rapidly in the watershed. A portion of the acreage was formerly cultivated. t A. It ~s.~.,,t~ yh.K f.`,.,..• X51 t±g~~l~ to 4 rte ~t.X' •.1.. \,4. r is `ll~a .1.~:! ~rY t}, . jl"`~ 7.Y` •i .i v.... Y r ~I lr r 5 r. ~A 1 1 i ' Legumes grown on cultivated land as shown above is a very important phase in obtaining proper land treatment. ' 4-27041 8-07 16 Conservation Program (table IA). 'fable 1 includes estimates of the acreage in each major land use which will receive accelerated land treatment during the 8-year installation period. These measures will be established and maintained by the landowners and operators in cooperation with the local soil and water conservation districts. ' In addition to the presently available technical assistance, $40,850 will be made available to accelerate planning and establishment of needed prac- tices and measures. There are 360 basic conservation plans covering 98,280 acres. It is ex- pected that during the 8-year installation period, 160 additional basic ' plans will be prepared and 167 revised. Following is the schedule for completing the., needed soil surveys during ' the installation period: Acres to be Surveyed First Year 360000 Second Year 40,000 Third Year 38,930 ' Total 1149930 Man-Year Requirements First Year .61 Second Year .68 Third Year .66 Total 1.95 The accelerated application and maintenance of land treatment measures is particularly important for protection of the 38,971 acres draining into planned floodwater retarding structures. The ap?lied land treatment meas- ures will reduce the sediment which would be delivered to the floodwater retarding structures by about 18 percent. There are 106,629 acres of the watershed which do not have any control from floodwater reta:ding struc- tures. On these lands, the establishment and maintenance of land treat- went measures constitutes the only planned measures. Land treatment meas- ures are important in reducing scour damages on the 6,912 acres of flood plain. Conservation cropping systems including such land treatment practices as cover and green manure crops, contour cultivation, and improved residue- conserving tillage operations will be established on approximate.'y 10,838 acres of cropland. These farming practices will improve water-ho.ding capacity, increase infiltration rates, improve fertility levels, and reduce erosion of the soil. About 200,640 linear feet of gradient terraces will be built and provided with needed grassed waterways to control erosion and ' retard runoff from the more rolling lands. Establishment of needed water- ways will precede construction of terraces. ' 4~21Q~6 f-If ' 17 The trend in upland farm areas is toward retirement of eroded areas from cropland use to hay or pasture. Pasture and hayland management will be practiced on 47,020 acres of improved pasture. Approximately 5,469 acres of this area will be renovated 1)y seeding and fertilizing. Thirteen thousand four hundred acres will be improved or reestablished by either ' seeding or sodding to attain a good base grass cover. Special grazing control will be carried out and fertilizers applied as needed. Approxi- mately 1,000 acres will be cleared of trees and brush. ' Application of wildlife area improvement measures, including stocking of fish in farm ponds and sediment pools of floodwater retarding structures, will enhance upland game, fish, and waterfowl habitats. Plantings in ' field borders and on grassland will furnish food and cover for wildlife. Excellent cover will be established within the fenced areas on the dams and emergency spillways of floodwater retarding structures and will furnish additional areas of wildlife habitat. 1 The installation of land treatment measures will reduce the total annual erosion in the watershed by approximately 15 percent. Infiltration will be increased by the improvement of cover in the cultivated areas and in- creased density and growth in the pastured areas. Terraces, diversions, and waterways will slow the runoff from cultivated fields. r Structural Measures A total of 17 floodwater retarding structures are required to provide the ' desired protection to the watershed and reduction in floodwater and sedi- ment damagee, to flood plain lands (figure 6). All planned structural measures are located in Denton County. ' Figure l shows a section of a typical floodwater retarding structure. The capacity of tha 15 floodwater retarding structures above U. S. Highway 377 totals 20,733 acre-feet. Of this total, 5,065 acre-feet is provided for sediment accumulation over a 100-year period and 15,668 acre-feet for floodwater detention. Runoff from 54 percent of the watershed above U. S. ' Highway 377 will be retarded. Floodwater detention in Sites 1 through 15 represents an average of 5.04 inches runoff from the area upstream from these structures. The amount of runoff controlled by each structure is ' shown in table 3. The total capacity of the two floodwater retarding structures on Pecan Creek is 1,311 acre-feet. Of this total, 101 acre-feet is provided for sediment accumulation and 1,210 acre-feet for floodwater detention. Run- off from 56 percent of the watershed above State Highway 24 will be re- tarded. Floodwater detention in Sites 16 and 17 is the equivalent of 8.60 inches runoff. No structural measures are planned on Timber Creek. Residential develop- ments and high land value sake it infeasible to install structural meas- ures to cbtain agricultural benefits. 18 All applicable State water laws regulating the appropriation of water or the diversion of streamflow will be complied with in the design and con- 6 ,ruction of structural measures. Details on quantities, coat, and design features of structural measures are shown in tables 1, 2, and 3. ' EXPLANATION OF INSTALLATION COSTS The estimated cost of planning and installing land treatment measures dur- ing the 8-year installation period, including expected reimbursement from Agricultural Conservation Program funds, is $1,915,986 based on current progrAm criteria. Accelerated technical assistance will be provided to landowners and operators through the soil and water conservation districts by the Soil Conservation Service at an estimated cost of $40,850 from flood prevention funds. These land treatment costs are based on present prices being paid by landowners and operators to establish the individual measures. Estimates of the kinds, amounts, and costs of land treatment measures were furnished by the Denton-Wise and Dalworth Soil and Water Conservation Districts. Land, easements, and rights-of-way for the floodwater retarding structures will be furnished by local interests at no cost to the Federal government. The local cost for the floodwater retarding structures, estimated to be $541,800, consists of land, easements, and rights-of-way ($532,650), re- locating and clearing obstacles ($6,200), and legal fees ($2,950). Construction costs for the 17 floodwater retarding structures, estimated to be $1,135,180, include the engineer's estimate and a 10 percent allow- ance for contingencies. The engineer's estimate was based on unit costs of structural tw asures constructed in similar areas and modified by special conditions inherent to each individual site location. The cost of instal- lation services is estimated to be $280,360, including engineering and administrative costs. The total construction and installation services costs fcr these measures is $1,416,540 and will be borne by flood preven- tion funds. The total cost of installation of the structural measures is estimated to be $1,958,340. ' The estimated schedule of obligations for the installation period for the project, including installation of both land treatment and structural measures, is as follows: ~-7f0~4 f-~T 19 F1 ood Fiscal: : Prevention : Other Year Measures Funds Funds Total (dollars) (dollars) (dollars) Fire[ Floodwater Retarding Structures 1 through 5 5269370 1099250 6359620 ' Land Treatment 5,106 234,392 239,498 ' Subtotal 5310476 343,642 8759118 Second Floodwater Retarding Structures ' 6, 15, 16, and 17 228,130 3072950 5369080 Land Treatment 51106 2342392 239,498 Subtotal 233,236 542,342 775,578 Third Floodwater Retarding Structures 7 through 14 662,040 124,600 7869640 Land Treatment 52107 234,392 239,499 Subtotal 661,147 358,992 1,0269139 Fourth Land Treatment 52107 234,392 239,499 Fifth Land Treatment 5,106 234,392 239,498 Sixth Land Treatment 5,106 234,392 239,498 Seventh Land Treatment 59106 234,392 2399498 Eighth Land Treatment 5,106 234,392 239,498 Total for Installation Period 1,4579390 2,416,936 3,8749326 i t t ' 4_230., 3-47 ' 20 EFFECTS OF WORKS OF IMPROVEMENT With the project installed and functioning as planned, agricultural lands can be managed more efficiently. Marginal cropland will be removed from cultivation and the hazards of flooding will be reduced on the flood plain lands. Land treatment measures will materially reduce losses by erosion ' on the upland areas and losses by scour on the flood plains. Structural measures will reduce flood and sediment damages on the benefited areas. ' It is expected that there will be an increase in the production of non- surplus crops such as grain sorghums, hay, and truck crops. An increase in the amount of improved pasture is expected to result in more 1 livestock production which will further diversify agricultural operations. Development and preservation of wildlife measures will improve g..re habitat and result in greater incomes to landowners from hunting fees. Increased net returns from more efficient operations and increased produc- tion will raise the standards of living of the local people. The improved living standards will stabilize the farm families and provide greater opportunities for advanced formal education. With the installation and operation of the project, 5 of the 8 major floods such as those which occurred during the 20-year evaluation period, 1944- 1963, would be reduced to minor floods. Average annual flooding on Hickory and Pecan Creeks would be reduced from 3,913 to 1,129 acres. Including recurrent flooding on Hickory and Pecan Creeks, the average annual area flooded three feet or more in depth without project is 435 acres. This is reduced to 135 acres after project installation. The following table shows the acres flooded by storms of specified fre- quencies without and with the project: Average Recurrence Evaluation 50 Percent Chance : 10 Percent Chance : 4 Percent Chance ' Reach : Without 'th : Without : With : Without With (Figure 5) Project : Prk ect : Project : Project : Project Project (acres) (acres) (acres) (acres) (acres) (acres) I 41 33 63 47 76 53 II 19160 625 1,461 1,331 19500 19410 III 307 18 437 348 460 395 ' IV 115 23 554 Al 625 185 V 35 34 106 96 140 135 VI 231 10 778 164 915 260 VII 45 3 94 18 103 11 VitI 77 54 123 77 137 88 IX 218 160 316 203 320 210 X 1/ 706 - 427 - 470 - ' Total 2s435 960 4,359 2,395 4,74E 20747 1 Lan treatment measures only. 1 21 Application of the planned land treatment practices is expected to reduce the total annual soil loss from 345 to 293 acre-feet, a reduction of 15 ' percent. The annual flood plain scour damage on 406 acres is expected to be reduced ' 76 percent. Nine percent will be attributable to land treatment measures and 67 percent to structural measures. After the project is installed, a 48 percent reduction in overbank deposi- tion on 585 acres will be effected, with 15 percent resulting from land treatment measures and 33 percent from structural measures. It is estimated that 130 acre-feet of sediment from this watershed is de- posited annually in Garza-Little Elm Reservoir under present conditions. This damage will be reduced to 70 acre-feet annually with the project III- stalled. Without the project, a 48-hour 25-year frequency storm will produce 6.53 inches of runoff from the watershed. Such a storm occurred on May 24-25, 1957. The runoff from this storm on Hickory Creek and tributaries pro- duced an estimated peak discharge of 28,990 cubic feet per second at the reference valley section No. 5 (figure 3). Runoff from this storm inun- dated 4,335 acres of flood plain land below the proposed floodwater retard- ing structure sites. With the project installed, the peak discharge from this storm would have been reduced to 19,200 cubic feet per second. The area inundated with the project would have been reduced to 3,012 acres. Figure 3 graphically illustrates the reduction at valley section No. 5 for the storm of May 29-30, 1946 (2.56 inches of rainfall, 2.03 inches of run- off), approximating a 2-year frequency storm. Reduced flooding will make it possible for farmers to increase the produc- tivity of flood plain land and to plan cropping systems which will result in greater net returns. I'he flood threat from a recurrence of the storms in the evaluation series would be eliminated from 1,323 acres on Hickory and Pecan Creeks, permitting more intensive use of this fertile land. With the installation of floodwater retarding structures 16 and 17, the urban area along Pecan Creek tributary through Denton will be protected against flood damage from the runoff produced by a storm expected to occur on an average of once in 100 years. It is expected that with adequate flood protection, some relatively large tracts of land now idle or in low value agricultural use may be converted to high value residential, commer- cial and industrial uses. OpportunitieP will also exist for the develop- ment of other smaller scattered areas. No benefits were estimated for chsages in land use which might take place following project installation. It is expected that intensification will occur on about 1,000 acres of the agricultural flood plain on which flooding is expected not more often than once in three years on the average. A large amount of this change will be 6-13016 3 _61 2 from pasture and wooded pasture to improved pasture and hayland. Allotted crops are minor and no significant changes are expected. ' Landowners of flood plain lands will be able to carry out a more diversi- fied and intensified agricultural program. Shifts in land use will reduce the acreage of cropland in the watershed by about 13,439 acres, or 26 per- cent. An estimated 85 landowners and operators of 6,912 acres of flood plain will be benefited directly by the project. ' The most severe damage to roads, bridges, and railroads is caused by floods that cover 75 percent or more of the flood plain. With the project in place, the number of floods included in the 20-year series that would inun- date 75 percent or more of the flood plain would be reduced from 3 to 0. The reduction of these larger floods would decrease inlirect losses result- ing from traffic rerouting and marketing delays by approximately 76 per- cent. - Percent of Number of Floods is 20-Year Series Flood Plain Covered Without Project _ With Project ' 50 - 75 8 3 75 - 100 3 0 Some loss of wildlife habitat will result from the clehring and inundation of sediment pool areas. All sites will offer opportunities for fish pro- duction and provide waterfowl habitat where none existed previously. Wild- life habitat in flood plain areas will be improved by reduction of fre- quency, depth, and duration of flooding. Upland habitat for wildlife will ' be enhanced by the application of land treatment. The sediment pools of all floodwater retarding structures will be open for public use on a fee basis or by landowners' permission and will provide neighborhood recreational opportunities that would not be available locally. Facilities will be available for recreational uses such as fishing, swim- ming, picnicking, boating, camping, and hunting. Peak recreation use is ' expected to occur from May through September, with fishing and hunting continuing throughout the year. For these pools, it is estimated that here will be an additional 12,750 visitor-days annually with a peak daily use of 451 visitors. The project will create additional employment opportunities for local residents. Firms contracting for installation of the structures will employ some of their help locally. The operation and maintenance of pro- ject measures over the life of the project will also provide employment opportunities for the local residents. Secondary benefits, including increased business activity and improved economic conditions in the surrounding communities, will result from the installation of the project. In addition, increased farm production will provide a market for both labor and products used in farming. The in- creased production will provide added income for farm families, thereby t-77046 3 -e1 23 improving their standard of living. Economic activities will be stimu- lated by sales of fishing equipment and other items associated with im- proved recreational opportunities. These secondary benefits will have a favorable effect on the watershed and in the surrounding areas. In addi- tion, there are intangible benefits such as increased sense of security r.ad the opportunity to plan farm operations without consideration of fre- quent flooding. Local secondary benefits were considered to be equal to 10 percent of the direct primary benefits plus 10 percent on the increased costs that primary producers will incur in connection with increased pro- duction. PROJECT BENEFITS The estimated average annual flood damage (table 5) within the watershed will be reduced from $82,060 to $19,575, a reduction of 76 percent. ' Approximately 7 percent of the damage reduction benefits will result from land treatment measures; all the remainder will accrue to the structural program. ' The total benefits from structural measures are estimated to be $90,879 annually. It is estimated that benefits from more intensi,,e use of flood plain will be $15,160 annually after discounting for a 5-year lag in ' accomplishment. It is estimated that the project will produce secondary benefits averaging $9,634 annually in the local area. This amount which excludes indirect benefits in any form, consists of $7,595 benefits stemming from the pro- ject and $2,039 benefits induced by the project. Secondary benefits of national significance were not considered pertinent to the evaluation. Therefore, only those benefits of a local or area nature were considered in the economic evaluation. Incidental recreation benefits (picnicking, fishing, and hunting), based on an estimated value of 85 cents per visitor-day, will equal $7,881 annually for structures open for public recreational use. Facilities will be moderately developed. Allowance was made for associated costs of 15 cents per user-day for repairs, maintenance, and operation of facilities and liability insurance. In addition to the monetary benefits, there are other substantial benefits which will accure to the project such as enhanced land values in the vicin- ity of floodwater retarding structures, an increased sense of security, better living conditions, and improved wildlife habitat. None of these additional benefits were evaluated in monetary terms; nor gave they been used for project justification. ' COMPARISON OF LENEFITS AND COSTS Average annual benefits from structural measures, excluding secondary bene- fits, are estimated to be $81,245. The average annual cost of these struc- tural measures (amortized from total installation cost plus operation and maintenance), is estimated to be $65,640 providing a benefit-cost ratio of 1.2 to 1. 4-dose 3-et 24 Total benefits, including secondary bent its, from structural measures w Ul provide a benefit-cost ratio of 1.4 to 1 (table 6). ' PROJECT INSTALLATION During the 8-year installation period, individual landowners and operators ' will establish land treatment measures. The land treatment practices are itemized in table 1, which shows aCLe$ to be treated. The goal is to have at least 75 percent of the land treatment applied at the end of the instal- l , lation period. Schedule for completion of planned land treatment during the installation period is as follows: . Fiscal Year : Cropland ; Pastureland Rangeland Wildlife Land : Total (&cres) (acres) (acres) (acres) (acres) First 20596 4,702 19180 21 82499 Second 20855 5,172 19298 22 9,347 Third 39115 59642 19416 24 100197 Fourth 30115 5,642 10416 24 10,197 Fifth 30375 62113 1,534 27 119049 Sixth 3,635 6,583 1,652 28 11,898 Seventh 39635 6,583 19652 28 119898 _EiRhth 3,635 6,583 1,652 28 11,898 Total 25,961 479020 119800 202 84,983 Technical assistance in the planning and application of land treatment is provided under the going programs of the soil and water conservation dis- tricts. A standard soil survey is in progress and adequate surveys have been completed on 30,670 acres. There are 114,930 additional acres in the watershed needing soil surveys. This work will be completed during the installation period. The governing bodies of the Denton-Wise and Dalworth Soil and Water Con- servation Districts will assume aggressive leadership in accelerating the land treatment program. The landowners and operators will be encouraged to apply and maintain soil and water conservation measures on their farms and ranches. District-owned equipment will be made available to land- owners and operators in accordance with existing arrangements. ' Additional flood prevention funds will be used for technical assistance to accelerate installation of land treatment measures during the 8-year in- stallation period. These funds, estimated to be $40,850, will be used by the Soil Conservation Service to assign additional technicians to the local districts to accelerate the application of soil and water conservation measures. The County Agricultural Stabilization and Conservation Service Committees will cooperate with governing bodies of the soil and water conservation 6-23066 1-67 25 districts in selecting practices which will accomplish conservation objec- tives. The Texas Extens!on Service will assist in the general educational phase of the program ;,y furnishing information to landowners and operators in the watershed. The Soil Conservation Service will contract for th4, construction of the 17 floodwater retarding structures, prepare plans end specifications, super- vise construction, prepare contract payment estimates, make final inspec- tions, certify completion, and perform related tasks for the installation of these structural measures. ' The local sponsors will provide, at no cost to the Federal government, all the land, easements, rights-of-way, legal fees, and relocation of existing improvements as needed for the construction of the floodwater retarding structures. The structural measures wLll be constructed pursuant to the following conditions: 1. The requirements for land treatment in the drainage area above structures have been satisfied. 2. Land, easements, and rights-of-way have been secured for all structural measures or for a group of structures in a hydrologic unit, or written statements are furnished by the appropriate sponsoring local organization(s) that their rights of eminent domain will be used, if needed, to secure any remaining easements within the project installation period, and that sufficient funds are available acrd will be used to pay for these easements, permits, end rights-of- way. 3. operation and maintenance agreements have been executed. 4. Flood prevention funds are available. FINANCING PROJECT INSTALLATION Federal assistance for carrying out the works of improvement described in this work plan will be provided under the authority of the Flood Control Act of 1944, as amended and supplemented. The needed land treatment measures will be installed by landowners and operators under agreements with the Denton-Wise and Dalworth Soil and t Water Conservation Districts. Reimbursement under the Agricultural Conser- vation Program will be available for thc9e measures which are eligible for payments based on present program criteria. Financing for the farmers and ranchers share of the cost can be arranged through local lending institu- tions and the Farmers Home Administration. The cost of technical assist- ance for land treatment measures will be borne by flood prevention funds. 4-23345 3-67 26 Landowners were contacted by the local sponsors during development of the work plan, and it is expected that most of the casements and rights-of-way I will be donated. Denton County Commissioners Court will exercise power of eminent domain as may be needed to secure rights-of-way necessary for in- stallation of floodwater retarding structure Sites 1 through 15. Funds I are available for this purpose in the County general fund for roads and bridges. The City of Denton will exercise power of eminent domain as needed to I secure the rights-of-way needed to install floodwater retarding structures 16 and 17. A bond election in the amount of $250,000 has been approved for this purpose. I The sponsoring local organizations do not plan to use a Farmers Home Admin- istration loan for this project. I PROVISIONS FOR OPERATION AND MAINTENANCE Land Treatment Measures I Land treatment measures will be maintained by the landowners and operators of farms and ranches on which the measures are applied. Representatives of the soil and water conservation districts will make periodic inspections of the land treatment measures to determine maintenance needs. Landowners and operators will be encouraged to perform the management practices and needed maintenance. Structural Measures I The estimated annual operation and maintenance cost is $1,760 for the 17 floodwater retarding structures. ' Specific operation and maintenance agreements will be executed between the Soil Conservation Service and the responsible organization prior to the issuance of invitation to bid on construction of any of the structural measures included in this work plan. The Denton County Commissioners Court will be responsible for the operation and maintenance of floodwater retarding structures 1 through 15. The two structures to be installed on Pecan Creek, Sites 16 and 17, will be main- tained and operated by the City of Denton. Both the Court and the City will budget each year sufficient funds for the operation and maintenance of the floodwater retarding structures of which they are responsible. The Court and the City will provide money for this purpose from the Denton County road and bridge fund and the city general fund respectively. Maintenance will be accomplished through the use of contributed labor and equipment, by contract, by force account, or by a combination of these methods. The structural measures will be inspected jointly by representatives of the soil conservation district, the County Commissioners Court or the City r z of Denton after each heavy streamflow. The Soil Conservation Service representative will participate in these inspections at least annually for the first three years following the installation of each structure and for successive years if unusual conditions warrant. Inspection will include items such as the condition of the principal spill- way and its appurtenances, the earth fill, the emergency spillway, the vegetative cover, and the fences and gates installed as a part of the structure. ' The Soil Conservation Service will furnish technical guidance and informa- tion necessary for the operation and maintenance program. Provisions will be made for free access of representatives of sponsoring local organiza- tions and Federal representatives to inspect and provide maintenance for all structural measures and their appurtenances at any time. r r r r r r r r r r ' 28 r TABLE 1 - ESTIMATED PROJECT INSTALLATION COST Hickory Creek Watershed, Texas ' (Trinity River Watershed) Price base% 1966 tot mued Cos[ Dollars Installation cost Item Unit Number : Ee4cral Other Total LAND TRLATl ENT ' Soil Conservation Service Cropland Acre 25,961 928,111 9289111 Pastureland Acre 470020 - 660,780 660,780 Rangeland here 11,800 283,435 283,435 Wildlife Land Acre 202 2,810 2,810 Technical Assistance (Accelerated) 40,850 40,850 SCS Eubtotal 84,983 40,850 1,87-3,136 1,915,986 TOTAL LAND T124MNT 84.983 40,850 1,575,136 _ 1,913,986 BTERcT M MM MS Soil Conservation Service floodwater Retarding structures No. 17 1,136,180 1 136 180 Subtotal - Construction 1,136,18 1,136,160 ' Installation Sevices Soil Conservation Service Engineering Services 180,210 - 1800210 Other 100,150 - 100,150 SCS Subtotal 280,36 260,360 Subtotal - Installation Services 280,360 280.360 Other Costs - 4 ` La, Easements, and Rights•of-Way - 538,850 5380850 Le al Eaas 2 950 2 950 00 Subtotal - other Costa 541350 1 8 5 1 800 TOTAL STRUCTURAL MEASURES 1. 1 .540 541,800 1,9583~ TOTAL PROJECT 1,457,390 2,4160936 31874,326 Sub SCS 19457,390 2,4169936 3,8740326 TOTAL PROJECT 1,4570390 2,416,936 3,874,326 Flood prevention funds. Includes reimbursement from ACP funds under going program. October 1966 M r ~ M" $40 i • S ~ r' h' .f L 29 TABLE IA - STATUS OF WATERSHED WORKS OF IMPROVEMENT ' Hickory Creek Watershed, Texas (Trinity River Vater0.ed) Price Base: 1965 Total Applied : Cost Measures 110it to Date I/• (Dollars) 2/ LAND TREATMENT Cropland Conservation Cropping System Acre 20,542 209542 Contour Farming Acre 1,640 820 Cover and Green Manure Crop Acre 10643 169450 Crop Residue Use Acre 12,859 12,859 Diversion Foot 539476 4,813 Grasses and Legumes in Rotation Acre 3,266 249495 Grassed Waterray or Outlet 4c re 215 19,250 Terrace, Gradient Foot 432,960 17,318 Terrace, Parr-i?el Foot 5,280 317 I Pastureland Bru~ sS Caitrol Acre 20180 39,240 Farm Pond No. 375 750000 I-and Clearing Acre 1,490 52,150 Pasture and Hayland Management Acre 37,900 189950 Pasture and Hayland Planting Acre 9,672 241,800 Pasture and Hayland Renovation Acre 2,050 51,250 Range Deferred Grazing Acre 8,840 4,420 Range Proper Use Acre 99200 4,600 w Wildlife Land Wildlife Habitat Development Acre 503 5,030 Wildlife Habitat Preservation Acre 175 875 TOTAL LAM TREATMENT 6109179 1/ As of July 1964. Excludes reimbursement from ASCS funds under going programs. 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October 1966 41 ' 34 (ABLE 5 - ESTIMATED AVERAGE ANNUAL FLOOD DAMAGE REDUCTION BENEFITS Hickory Creek 'Watershed, Texas (Trinity River Watershed) ' (Dollars) - :Estimated Average Annual Damage: Damage Without With : Reduction Item _ Protect Protect • Benefits Floodwater Crop and Pasture 150129 60586 89543 ' Othe: Agricultural 71806 2s473 5033 !Nonagricultural Urban 27,100 - 27,IO0 Road and Bridge 17.074 5,674 11,400 Subtotal 679109 14,733 522376 ' Sediment Overbank Deposition 1,434 748 686 Garza-Little Elm Reservoir 2,825 1,521 1,304 ' Subtotal 4,259 2,269 19990 Erosion Flood Plain Scour 30232 793 2,439 Indirect _ 7,460 19780 50680 TOTAL 829060 199575 62,485 1/ Price Base: Adjusted Normalized Price Index, Advisory WS-179 Hay 1966. October 1966 4-"043 t-N ; • gig ' 35 0 0 0 0 %W W4 04 ~r Y1 ~t N .4 Op '-t O O O N N ~1 ~O H ~y co co ' G w w w N ~ k N C; u in e~ O~ O • • E. • to a 119 D Yv 1a She L M „ rl y P4 v w N W Oq 4W m C D H w a0 Z v v M .>i c n co P4 0 44 u O u P4 N W 41 C41 V4 T ~S o C ,o ~ eo O ao 4M r4 i a a,+ bi 4 A ~ ~ u E01 is oll ~ a;: e. S.` A r - 36 1 TALE 7 - NSTRUCTION NI' Hickory Creek Watershed, Texas (Trinity River Watershed) ' (Dollars) ' Unit : Measures in Annual Annual No. : Construction Unit ; benefit 1/; Cost 1 Floodwater Retarding Structures Nos. 1 through 5 26,540 210420 2 Floodwater Retarding Strw_.Mr:: Was. 7 tbCausb 11 21,353 190420 3 Floodwater Retarding Structures Nos. 6 r and 15 49624 30810 4 Floodwater Retarding structures Nos. 12 ' through 14 plus Units 1, 2, and 3 560517 519820 5 Floodwater Retarding Structures Nos. 16 and 17 - 341362 13,820 1/ Price Base: Adjusted Normalized Price Index, Advisory WS-17, May 1966. installation costs based on 1966 prices and amortized for 100 years at 3 1/8 percent. October 1966 1 r r ' 37 ' INVESTIGATIONS AND ANALYSES ' Land Use and Treatment The status of land treatment measures for the watershed was developed by ' the soil and water conservation districts with assistance from Soil Conser- vation Service work unit personnel at Denton, Dallas, and Fort Worth, Texas. ' At a meeting held in Denton, the measures for land treatment required to establish a sound soil, water, and plant conservation program for the watershed were determined. ' Trends in farming operations, expected changes in land use, soil condition, land tenure, and other pertinent data were used. From these data, land treatment measures expected to be applied during the 8-year installation ' period were selected. Past rates of application were examined, and the need for funds to be used for accelerated technical assistance was deter- mined. i Land treatment practices that have been applied on farms under conservation plans obtained from accomplishment records maintained by the Soil Conserva- tion Service, were expanded to represent those applied to date within the watershed. The II-condition soil-cover complex numbers were computed under present ' conditions considering soils, land use, and hydrologic cover. These compu- tations wero based on land use, cover, and completed soil survey informa- tion which was expanded to represent the watershed area. Further computa- tions with the land treatment measures assumed to be in place were cum- pleted to develop the after-project curve numbers. ' Based on conservation needs, an estimate was made of the measures to be applied in the 8-year installation period. The acres to be treated and cost of treatment measures are shown in table 1. ' Table lA reflects the cost of land treatment measures applied prior to development of the work plan. Engineering The following steps were taken in making the engineering investigations: ' 1. A base map of the watershed was prepared showing watershed boundary, drainage pattern, system of roads and railroads, and other pertinent information. a 2. A study of aerial photographs supplemented by field exam- inations was made to determine the limits of flood plain ' subject to flood damage. ~_:roes s-~~ ' 38 3. Probable sites for floodwater retarding structures were lo- cated by study of U. S. Geological Survey topographic maps ' and stereoscopic photo study. A field examination was made of all possible floodwater retarding structure sites. Those sites which did not show sufficient storage possibilities or ' in which obstacles were encountered making the site unfeasi- ble were dropped from further consideration. A base map was used to show locations of all structure sites that could ' possibly be used to evaluate alternate systems of structural measures needed to meet project objectives. 4. A system of 29 floodwater retarding structures was recom- mended to the sponsors for further consideration and de- tailed survey. ' 5. Engineering surveys were started after agreement was reached with the sponsoring local organization: on the locations of floodwater retarding structure sites to be studied. Surveys were carried out as follows: ' a. Horizontal control - The scale of aerial photographs was checked during mapping of the topography of the ' floodwater retarding structure sites. b. Vertical control - Existing U. S. Coast and Geodetic Surveys and U. S. Geological St:rvey bench marks were used to establish a system of temporary bench marks set at strategic locations. 'these were used in making surveys for proposed structural measures. ' c. Site surveys - Tentative capacity tables for the pro- posed structure sites were developed frcrti USGS quadrangle ' sheets and used as a guide in determining the extent of surveys needed. Topographic maps of the reservoir areas with 4-foot contour intervals and a scale of I inch = 660 feet were developed on aerial photographs. Cross section and profile data were obtained at pro- posed floodwater retarding structure centerlines, pipe- ' linen, utility lines, and roads involved in each site. After preliminary reservoir plans were accepted by local sponsors, detailed topographic maps of the emergency spillway areas were prepared with a scale of one inch equals 100 feet and a contour interval of 2 feet. Con- tour lines at the elevation of the top of the riser, the emergency spillway crest, and two feet above the emergency spillway crest were located on the ground and plotted on the aerial photographs. These surveys were used to develop data to finalize design, determine esti- mated installation coat, determine land rights require- ments, and to prepare final land rights work maps. ' a-ttoat t-s~ 39 ' 6. Design of floodwater retarding structures was initiated as soon as survey data was completed. Structure classific.tion and detention and sediment storage requirements for each structure site were determined from criteria outlined in Engineering Memorandum SCS-27 (March 14, 1950) and Texas ' State 19dnual Supplement 2441. After storage tables and curves were developed from topographic maps, principal and emergency spillway crest elevations were de:?rmined. Alter- nate locations for each dam were analyzed to determine the ' most economical and feasible site. The elevations of the sediment and detention pools were determined from the storage curves. The top of the riser was set by providing capacity for the expected 50-year sediment accumulation. In the structure which the 50-year sediment accumulation exceeded 200 acre-feet, a lower pool ' was set at the 200 acre-feet volume. Storage of water is limited by State law to 200 acre-feet unless a special use permit is obtained. The elevations of the emergency spill- ways wer: set by providing capacity for the detention and the 100-year sediment volume. Detention volumes in all structure sites meet or exceed the minimum criteria set forth in Engineering Memurandum SCS-27 (Rev. March 19, 1965) and Texas State Manual Supplement 2441. 7. Floodwater detention capacity was provided in all structures ' according to structure classification as follows: For class "a" structures - detainment of expected runoff from a 25-year storm event; class "b" structures - detainment of expected ' runoff from a 50-year storm event; class "c" structures - detainment of expected runoff from a 100-year storm event. The expected runoff from these three storm events was detor- ' mined from a regional analysis of stream gage records. 8. Appropriate emergency spillway design and freeboard storms for all structures were selected from figures 1 through 6 of Engineering-Hydrology Memorandum TX-1 as follows: Class "a" structures - figures 1 and 2; class "b" structures - figures 3 and 4; class "c" structures - figures 5 and 6. ' Spillway design and freeboard inflow hydrographs were de- veloped by the distribution graph method. The appropriate inflow hydrographs were routed through each reservoir by the Goodrich floodrouting method either graphically or by digital computer to determine the width of emergency spill- way and effective top of dam. Various combinations of spill- way widths and depths were computed to determine the most economical structure. ' 9. Construction costs were determined from a preliminary design and cost estimate of significant individual items such as embankment, principal spillway, clearing, and fencing. Unit ' A-2304% l-07 ' 40 ' prices were based on recent contracts of structures in sites with similar characteristics. Conditions peculiar to a par- titular site such as rock excavation are reflected in designs and cost estimates. 10. Structure data and cost distribution tables were developed ' to show for all proposed floodwater retarding structures, the drainage area, planned detention capacity, sediment volume, release rate for principal spillway, emergency spillway capac- ity, area inundated by the pools, volume of fill in the dam, estimated cost, and other pertinent data (tables 2 and 3). Hydrologic and Hydraulic The following steps were taken as part of the hydrologic and hydraulic investigations: ' 1. Basic meteorologic and hydrologic data were tabulated from Climatological Bulletins, U. S. Weather Bureau, U. S. Geo- logical Survey Water Supply Papers, an(4 iu:.al records. These data were analysed to determine average precipitation depth- duration relationships, seasona~ Gistribution of precipita- tion, frequency of occurrence of meteorological events, historical flood series, rainfall-runoff-peak discharge relationships, and the relationship u, geology, soils, and climate-to-runoff depth for single storm events. ' 2. Engineering surveys were made of valley cross sections, high water marks, bridges, and other data pertinent to determining flood and sediment damages. The cross sections were selected to represent the stream hydraulics and flood plain areas. Evaluation reaches were delineated in a joint study with the economist. Additional channel sections were surveyed within the urban area of Denton, Texas to determine channel and flood plain ' characteristics for purposes of making a detailed water sur- face profile study. ' 3. The watershed is divided into two parts for the purpose of determining runoff. The portion of the watershed draining into Timber Creek lateral includes a large amount of perme- able soils of the Cross Timbers Land Resource Area. This ' area is considered separately from the remainder of the watershed. ' The area draining into Fecan Creek lateral is separated into two parts. Due to the high runoff characteristics of the urb area along Pecan Creek, this area is considered sepa- l ratt..y from the remainder of the drainage area of Pecan Creek lateral. ' 41 ' Hydrologic conditions of the watershed for both before and with project were determined on the basis of soil groups, ' land use, land treatment, and cover conditions. The before-project i=-condition soil-cover complex curve number of 81 and the with-projec, curve number of 80 were ' determined for use on tba major portion of the watershed. Areas excepted are that drained by Timber Creek lateral and the urban area portion of Pecan Creek. ' For Timber Creek lateral, the before-project II-condition c+irve number of 75 and the with-project curve number of 74 ' were used. For the urban area only along Pecan Creek lateral, it was determined to use curve number 95. These curve numbers were ' determined from soil surveys with a combined acreage equal to 25 percent of the watershed area. 4. Cross section rating curves were computed from field survey data by the use of Manning's formula. 5. Runoff-peak discharge relationships were determined by flood routing four volumes of runoff in accordance with procedures set forth in Technical Release 20, "Computer Program for Pro- ject Formulation. Hydrology" (Central Technical Unit, Soil Conservation Service). Stage-discharge relationships along the concrete lined channel ' within the urban area of Denton, Texas were determined by mak- ing water surface profile studies. These studies revealed that floodwater retarding structures were needed to provide protection to the urban area from the runoff produced by a ' storm expected to occur on an average of once in 100 years (figure 4). 6. Stage-area inundated curves were developed from field survey data for each portion of the valley represented by a cross section. Stage runoff and stage area inundated curves were ' developed for each evaluation reach for existing watershed conditions. 7. The rainfall records from the Denton gage were studied for the period 1923 through 1963. From a tabulation of cumula- tive departure from normal precipitation, the 20-year peri.J 1944 through 1963 was determined to be representative of normal precipitation on the watershed. The historical evalu- ation series was developed from those years, with individual events limited to a period of 2 days. <-2!043 l-s7 1 + 42 8. Determinations were made of the area that would have been inun- dated by each storm of the evaluation series under each of the following conditions: a. The without-project conditions. b. The installation of land treatment measures for watershed protection. c. The installation of land treatment measures and floodwater retarding structures. ' 9. The evaluation series contained 44 storms that would cause flood damage at the smallest cross section, an average of approxi- mately two floods per year. 10. The runoff from the largest storm in the historical evaluation flood series was routed to determine the maximum flood plain area used in the computations of damages and benefits. Sedimentation Sedimentation investigations were made in accordance with procedures out- lined in Technical Release No. 12, "Procedures for Compur,.i; Sediment Re- quirements for Retarding Reservoirs," September 1959, U. b. Department of Agriculture, Soil Conservation Service, and "Guide to Sedimentation Inves- tigations - South Regional Technical Service Area," Marct. 1965, U. S. De- partment of Agriculture, Soil Conservation Service, Port iorth, Texas. Sediment Source Studies Sediment source studies were made in the drainage areas of the 17 planned floodwater retarding structures to determine the IGO-year sediment storage requirements. Detailed investigations were made in the drainage areas above 5 of the planned floodwater retarding structures and semidetailed studies were made for the remaining 1.2. Sediment source studies were also made in the drainage areas of 7 sites investigated but not included in the work plan. The following is a tabulation of the investigations and pro- cedures used in determining sediment rates: A 1. Detailed field surveys to determine soil loss by sheet erosion included: mapping of land use, cover conditions, land treat- ment, and slope lengths. Gully and streambank channel investi- gations included mapping lengths, depths, and estimated lateral erosion. 2. Utilization of soils and slope data from soil survey photo- grapha. 3. Annual soil loss was computed in tons by sediment sources (sheet, gully, and streambank erosion). The Musgrave soil equation was used in sheet erosion calculations. ' ~-:ewe g_~s e 43 I ' 4. Semidetailed field surveys to determine soil loss rate con- sisted of mapping land use and studying soils, topography, and erosion. Computations were based on erosion rates deter- mined by detailed studies of similar areas. 5. Erosion rates were adjusted to reflect the effect of planned land treatment. 6. Sediment storage requirements for all structures were deter- mined by adjusting annual soil loss for expected delivery ratios and trap efficiency. 7. Allowance for density differences between soil in place and sediment were made for the required sediment storage volumes. These densities were based on volume weights ranging from 43 to 45 pounds per cubic foot (sediment) and 82 to 83 pounds per cubic foot (soil in place). 8. Allocations of sediment in structures were based on the following (all sites in the Grand Prairie Land Resource Area); Period of Structure Condition of Allocation Deposition Pool Sediment (Percent) First 50 Years Sediment Submerged 85 Detention Aerated 15 Second 50 Years Detention Aerated 100 Flood Plain Sediment and Scour Damages The following investigations were made to determine the physical damages to the flood plain. 1. Examinations were made along the valley cross sections (figure 3), making note of the depth and tex►are of de- posits, soil conditions, scour channels, stream channel aegradation or degradation, and other pertinent factors contributing to flood plain damage. 2. Estimates of past physical flood plain damage were obtained through interviews with landowners and operators. 3. Tables were developed to show percent damage by texture and depth increments for sediment and by depth and width for scour. 4. The areas of sediment and scour damages were measured and tabulated by percent damage categories. 4-:7045 9 -57 S 44 i 5. The damage to the productive capacity of the flood plain was assessed by percent for each type damage. 6. Damages were summarized by evaluation reaches. Estimates of recoverability of productive capacities were developed from field studies and interviews with farmers. 7. Using the average annual erosion rates as a basis, sediment yields to the flood plain were estimated by sediment sources for present conditions, with land treatment measures installed, and with land treatment and structural measures installed. 8. Reductions in sediment yields were adjusted to reflect the e relative importance of each sediment source as a contributor of damage. The reduction of monetary damage from overbank deposition was based on reduction in sediment yield. The reduction of scour damage is based on reductions in depth and area inundated. Sediment Deposition to Garza-Little Elm Reservoir That portion of Hickory Creek which drains into Garza-Little Elm consti- tutes ten percent of the total watershed area above the reservoir. The estimate of the present annual sediment yield from Hickory Creek watershed to the reservoir is based on a detailed study of sediment sources and the use of delivery ratio curves developed by the Soil Conservation Service. It is estimated that the present annual rate of deposition is 0.72 acre- foot per square mile. With the project installed in Hickory Creek water- shed it is expected that the rate of deposition to the reservoir will be reduced to 0.39 acre-foot per square mile. s A sedimentation survey of Garza-Little Elm Reservoir made in September 1960 by the U. S. Army Corps of Engineers showed an annual rite of deposition of 1.46 acre-feet per square mile during the 5.88 year period of record. Preliminary data from the sedimentation resurvey of 1965 indicates an annual rate of deposition of 0.47 acre-foot per square mile for the five year period since the 1960 survey. The weighted average ajinual rate of deposition for the 10.88 year period of record is 0.97 acre-foot per square mile. The primary reason for the wide variation of sediment yield for the two periods is because of above normal runoff during the first period and below normal runoff for the second. It is believed that the study of sediment sources in Hic"vey Creek water- shed is more representative of its sediment contribution to Garza-Little Elm Reservoir than the 1960 and 1965 sedimentation surveys. The surveys reflect rates of deposition from a wide range of sediment sources in the 1,660 square mile drainage area of the reservoir. Additionally, the in- stallation of land treatment measures, land stabilization measures, and 80 floodwater retarding Structures (June 30, 1965) have w erially reduced sediment contribution to the reservoir. 4_13040 3-37 45 Geologic Preliminary geologic investigations were made at each of the floodwater retarding structure sites to obtain information on the nature and extent of embankment materials, foundation conditions, and emergency spillway excavation that will be encountered in construction. These investigations included surface observations of valley slopes, alluvium, channel banks, and exposed geologic formations; seismic investigations; and hand auger borings. Description of Problems All structure sites are located on Lower Cretaceous strata of the Washita group. This group is composed of marine shaly clays, marls, and scb- ordinate limestones, having a total thickness of approximately 500 feet in the watershed. Toward the top is one sandy formation, the Pawpaw, which is the only exception to the non-sandy character of the group. The follow- ing tabulation shows, in descending order, the geologic formations of the Washita group and the sites occurring within their outcrops: Formation Sites Grayson Main Street 12 through 17 Pawpaw Weno 11 Denton 6 Fort Worth 5, 91 10 Duck Creek 1 through 4, 7, 8 Site conditions are closely relate;] for all formations within the group. Soils overlying the geologic strata are calcareous, silty clays, and gravelly clays. Seepage problems are considered minor because of the dominance of relatively impervious material and near positive cutoffs can be obtained at shallow depths at most site locations. Preliminary estimates of borrow volumes within the sediment pool and emer- gency spillway areas of Sites 4, 10, and 13 closely approximate embankment requirements. Detailed core drill investigations may reveal that addi- tional borrow will be needed from other sources. Construction materials are readily available within easement areas on these three sites. Ade- quate quantities of satisfactory materials are available within the sedi- ment pool and emergency spillway areas on the remainder of the sites. The soils of the borrow areas are classified CL, CH, and GC- Rock excavation is expected in the emergency spillways of Sites 3, 8, 99 and 11. The preliminary estimates are 10 percent of the total excavation on Sites 3, 9, and 11, and 25 percent for Site 8. All of the materials will be usable in the embankments. Detailed investigations, including exploration with core drilling equip- ment, will be made at all sites prior to construction. Leborstory tests as 04! 2 -47 ! 46 will be performed to determine the suitability and handling of embankment and foundation materials. Economic Basic methods used in the economic investigations and analyses are out- lined in the "Economics Guide for Watershed Protection and Flood Preven- tion," U. S. Department of Agr!culture, Soil Conservation Service, March 1914. Determination of Annual Benefits from Reduction in Damages Agricultural damage schedules were obtained by interviewing landowners and operators of approximately 40 percent of the flood plain. These schedules covered past, present, and future land use, crop distributicn under normal conditions, CLO1 yields, other agricultural losses, and depth of flooding. Supplemental data on normal crop yields were obtained from agricultural workers in the area. The present land use on all of the flood plain was obtained by field mapping. Analyses of this information formed the basis for determining the damage- able value and damage rates for various depths and seasons of flooding. The proper rates of damage were applied to the foods in the 'aistorical series, covering the period 1944-1963, inclusive. An adjustment was made to take into account the effect of recurrent flooding whet, several floods occurred within one year. Field studies indicated that land use, yields, frequency of flooding, and anticipated future use warranted the division of thl.s watershed into ten reaches. Consequently, a different damageable value was used for each reach. Estimates of damage to other agricultural property such as fences, livestock, on-farm roads, and farm equipment were made from the analysis of information contained in the flood damage schedules. The monetary value c: the pnysical damag-- to the flood plait land from erosion and sedi- ment was based on the value of the production lest. The estimate took into account the lag in recovery of productivity and the cost of farm operations to speed recovery. Damage from flood plain scour was related to depth of flooding and velocity, giving greater weight to deeper flows. Damage to Garza-Little Elm Reservoir for sediment deposition was detvr- mined by the straight line w7thod. The total cost (adjusted Io normal ized prices) of Garza-Little Elm Reservoir was used to determine the cost per acre-foot of storage lost by sediment deposition. Road and bridge damages were based ort information from the County Commis- sioners, Texas Highway Department employees, and residents of the water- shed. Urban damages in the City of Denton were based on information collected in the field on damages experienced from the 1957 flood and from other more recent floods. An evaluation was made of the damage that would occur from a 100-year frequency flood with the present stream channel improvements. .-7704! 7-N -AL 47 The field investigation showed that much of the flu'xl plain area on the upper end of the reach had been developed since 195', both in the form of residential and commercial areas. Indirect damages involve ,uch items as additional travel time for farmers, rerouting of general traff.c, school buses and mail deliveries, and costs of extra feed for livestock during and after floods. Based on information and data obtained from watersheds previously analyzed, it was determined that indirect damages approximate 10 percent of the direct damages. Owners and operators were asked what changes they would make in their flood pla?.n land use or cropping systems if flood protection were provided. They indicated that a shift would be made from pasture to hay, including alfalfa. Consequently, it is not expected that acreages of crops subject to allotments will be increased as a result of the project. Benefits from more intensive land use in protected areas have been estimated. Evaluation of incidental recreation benefits was I led on an economic analysts of existing structures and from past experience. This analysis indicated that the project will have an average of 12,750 visitor-days annually and net benefits of $0.65 per visitor-day, after allowances of $0.15 for associated costs. It was estimated that the capacity of the sediment pools would remain adequate for recreational purposes for 40 years and decline to zero at the end ;,f 50 year:. The incidental recrea- tional benefits were discounted t,) ::ilow for this depiction in capacity. The value of local secondary benefits stemming from the project was con- sidered to be equal to 10 percent of the direct primary benefits. This excludes all indirect benefits. The value of local secondary benefits induced by the project was considered to be equal to 10 percent of the increased costs that primary producers will incur in connet,ion with in- creased production. ~t The values of easements were determined through local appraisal, giving full consideration to current real estate market values. An estimate was made of the value of production lost in the pool areas after installation of the program. In this appraisal it was considered that the sediment pools would yield no production. The land covered by the detention pools would be used as pasture after installation of the structures. The aver- age annual loss in production within the floodwater retarding structures plus secondary costs therefrom were conpared with the amortized value of easements. The easement value was found to be greater and therefore was used in economic justification to assure a conservative benefit-cost analysis. Fish and Wildlife r The Bureau of Sport Fisheries and Wildlife, in cooperation with the Texas Parks and Wildlife Department, has completed a reconnaissance study of the Hickory Creek watershed and make the following observations and recommenda- t ions: h8 Fish habitat in the watershed is prima-ily in farm ponds. A small portion of the Garza-Little Elm Reservoir lies in the southeastern extremity of the watershed. The intermittent watershed streams support few fish. Principal species of fish in farm ponds and Garza-Little Elm Reservoir are largemouth bass, white bass, bluegill, white crappie, redear sunfish, green sunfish, and channel catfish. Carp, gars, and gizzard shad also are common in Garza-Little Elm Reservoir. The streams have a few sunfish and channel, catfish. Farm pond fishing is restricted to landowners and their invited guests. Garza-Little Elm Reservoir is open to public fishing. Fishing is insignificant in the project streams. There is no commercial fishing in streams and farm ponds in the watershed, and none is expected to develop in the future. That part of Garza-Little Elm Reservoir occupying a small portion of the watershed supports a com- mercial fishery for buffalofish, carp, and gars. This fishing is done by State contract netters and is expected to continue. With the project, the construction of 17 floodwater retarding structures and additional farm ponds woul%~ create good fish habitat In the watershed. These impoundments would reduce the amount of sediment deposited in G;rza- Little Elm Reservoir thereby improving fish habitat and prolongi,,g thz ' life of that reservoir. No commercial fishing would be expected to develop under with-the-project conditions, except for that in Garza-Little Elm Reservoir. The principal wildlife species in the watershed arc bobwhite, mourning dove, fox squirrel, cottontail, waterfowl, raccoon, opossum, armadillo, skunk, and .Wink. No big-game animals reside in the watershed, and none are expecteJ to do so in the future. Bobwhites, mourning doves, and cottontails are hunted intensively in the watershed. Hunting for fox squirrels dnd opossums is moderate to light. A few landowners lease a small amount of land for bobwhite hunting. These conditions would not be expected to change significantly without the pro- ject. During periods of migration, waterfowl make extensive use of available water in the watershed. They are hunted heavily during the waterfowl season. Raccouns are hunted for sport with dogs, but there is no fur trapping in the watershed. With the project, planting lodumes, cover and gree.i manure crops, conser- vation cropping systems, wildlife habitat development, and wildlife habitat preservation would be beneficial for upland game. Flood protection below the floodwater retarding structures would improve wildlife habitat, par- ticularly for ground-nesting species. 4-2)04 9 1-67 49 The floodwater retarding reservoirs and farm ponds would oe of value to wildlife as a source of drinking water. Migrating waterfowl would use the Impoundments as mating areas. Brush control and land clearing would destroy wildlife habitat valuable to most upland game. Construction of the floodwater retarding reservoirs with sediment pools that maintain water until silted in would benefit fishing and hunting in the watershed. However, to realize the full fishing and hunting potential of the project, provision should be made to provide public access to all of the structure sites. There are certain measures that could be implemented in the project plan that would improve fish habitat and reduce the :oss of wildlife habitat. To promote fertility and reduce turbidity, upon completion of the struc- tures and prior to impoundment of water, the basins of the floodwater re- tarding reservoirs should be disked and planted to grasses or a small grain adaptable to the area. When practicable, the dams and selected reservoir areas should be fenced to prevent damage to the dam and muddying of the water by livestock. A watering device installed below the dam and outside of the enclosed area could be used to water livestock. If this is not feasible, watering lanes could be provided to a selected area of the reservoirs. Clearing and charting of seining areas in the larger reservoirs to permit seining would be an aid to management of the reservoirs for fishing. Suit- able seining areas could be provided at little additional cost if included in the project construction plans. Such cleared areas could be con- strutted in the process of securing fill for the dams. The Texas Parks and Wildlife Department should be consulted regarding the reservoir stocking requirements. Indiscriminate stocking would be detri- mental to the sport fishery. Where channel catfish are approved for stock- ing, suitable spawning devices should be installed. Sewer tiles, barrels, and old tires have been ssed successfully as channel catfish spawning shelters. Consistent with project objectives, as much brush ant' timber as possible should be retained in the watershed for wildlife. Losses of brush and timber that result from project construction and inundation should be compensated for by planting appropriate vegetation at suitable locations such as on idle lands, eroded areas, stream banks, gullies, and along fencerows. The Texas Parks and Wildlife Department should be consulted prior to clearing for their recommendations relative to the retention of brush and timber. With a minimum of planning and expense, many floodwater retarding, erosion prevention, and soil building p:acticES can be made to improve fish and wildlife habitat. For example, hedgerow plantings provide excellent food and cover for various species of wildlife. They also delineate field boundaries, reduce erosion, establish contour guidelines, and serve as living fences or screens. Likewise, field border plantings help f-ontrol a4T149 ]-!T sa erosion, protect edges of fields that are used for turnrows or travel lanes for farm machinery, and also provide food and cover for wildlife. 1 Appropriate plantings around reservoirs and ponds would enhance the beauty and scenic qualities of the watershed. 1 In view of the above, it is recommended that: 1. Public access be provided to the floodwater retarding reser- voirs for fishing and hunting. 2. Upon completion of construction and prior to storage of water, the basins of the reservoirs be planted to grasses or small grains adaptable to the area. 3. Lav's adjacent to the periphery of the floodwater retarding dams and reservoirs 'oe planted to grasses and other bene- ficial vegetation tc prevent soil erosion and runoff of sedi- ment into the basin:i of the impoundments. 4. When practicable, the floodwater retarding reservoirs be fenced and watering devices installed below the dams and out- side of the fenced enclosures or adequate watering lanes be provided to selected areas of the pools. 5. Planned clearing and grainn; to permit fish seining in the reservoirs be included in the project construction plans. b. only fish species recommended by the Texas Parks and Wild- life Department be stocked in the reservoirs. 7. Channel catfish spawning devices be installed in the reser- voirs. 8. Clearing of timber and brush be kept at a minimum during construction of the floodwater retarding reservoirs and farm ponds. 9. Losses of timber and brush be compensated for by planting trees and shrubs suitable for wildlife at appropriate loca- tions such as idle lands, eroded areas, stream banks, gullies, and strips along fencerows and travel lanes. The above recommendations are in conformance with U.S.D.A. Soil Conserva- tion Service Biology Memorandum-7 (Rev. 1), National Standards for Biology Practices. If adopted as a part of the plan of development, losses of wildlife habitat would be mitigated and, additionally, fish and wildlife benefits would accrue to the project. A detailed study of the watershed by the Bureau of Sport Fisheries and Wildlife is alot considered necessary at this time. Shoul the sponsors desire, our Bureau, in cooperation with the Texas Parks and Wildlife Department, would be happy to be of further assistance. 4 -a,a! a-17 0 51 i ti \ V \ W 3L f ~i O ` •r i•r \ " rf W r ~ 2 L r{'rr? r1 0= II • I11 `I I f, f ~ I l l 11111 l •tf rrr ~ lIII ~ Lf . o Q !III ; .,l ~ c0 \ ILL. Iltl a ul J ~ I11 c. rr \ a \ U IIII u 3 A }d r v~; F- Cc 1 [ 11111111 I;I \ J yy.. I! I I ~ i ~ Q A~ ~ Q 3 IIIIII~If ~ w \ n Av I I I I O 1 1 1 1 :r \ \ N IE W \ 1 1111 11 1 y ~ II \ ~ 11111111 ~ o ~ v.. ~A~A A r 1 111 1i~. J 4v O II r IIE( O ICI I~ O 1 O III III ~u I ^ I I~ \ i lic I mi III j h H ~llf I 1 !fl `il \ a ! o I } Illllil.~.l,,. Il li l~ ~ cC 11 I ,1 I{I h \ 3 jljl rli N ~ II~~Ifl I 1111111 ~ I I \ flllll 1- 1111111 i~f~l~l 2 0 .`y IIII III h e 1111111 z ^ 1111111 uWi cc 111 m 1111~1~1 JIf i 1. 52 fl MCf LF6lND t m n~mu'rf d ~pml bM Drsre4 in l^r,(rMy.Ia.' ay rd In allYpv* tid o--- - NeAArne rlobe Co nltiroc tied undrrOA Is Cum lrA[1 G r:; fYJa• rev !ti W, Alto one ( arr//rncY Sordwry• _ l~opryeimrrr Groumf Gns dearlJ6lf0 Ftnc1 in rent/rVdiOn a, to to be rrmorrd snd silra(r/ by fre eon l"rc our. 1 Jeanr l NAee16 2w-'fewl4V,1++Iy.^"'rivn'//'rR7ch.tliti(v, ! T fro ~i. _ ,7.6---00•L..: ! r l4 Wm but, Colo d /ivatror. f 7 f.Y . _ r I~ Prin[tptl to be / tubriC~ar), M yl.hrr "ems of of emA o ~ 1 Sp'/!rw ~ Q-M Crnl(l6t[.! I Sea 2#,10o,, tofPr'nespo r Spillway ~ y7D S1+N100ontorDsm oe, \ ! sJt .Y Spillway or '~v IV I fdWm JIM Nowrit. 00 M'/an 0.6160 Or.ers;on LNalhr p0 v a~W (era 1 wnat rose, Ior A r C ° 611 11,0p,00 Lim A of 1 Qw ~t if , Iti e:.;e Lt fro - • I r-- rBorrow Areai r:' r [ J 11 [ t yl r I/ ' O r , 4 Pf nr t hed C;rl ale ; fl J SMw[ll 111.111 f!M'ur ~ 0AP t!F % Srrocleer Site No St A ' e a~ • 0 I I - ` I Sh If66. -r ~ wr Ifin Cou r [orated ir. l0'frncr w r h f i apprulmtlr/y 4S m'/e9 wn of Z L If 61607.6 A *,Ce tye Tr[2s. E,/ a It term + f oo r ``O too VICINITY MAP d j f/p!lrram roe see..$ustatLri111i6 A.oo it 000 6000 0too t/tjs_3 orlmrr(ene Tinpre+ GENERAL PLAN OF RESERVOIR Spillwaya no, srilHO PROFILE ON ~ OF EMERGEHCY~ SPILLWAY 19Hlen tolOfm {(n 0 •w uro nw 1140 \\w l1s,l MERHNCY SPILLWAY SCAL9IN fr[T 14' IYlrt dep CU" DA lA • M1.4f' D 76.00' PLAN OF EMBANKMENT AND SPILLWAYS L T ! ' A r tiro 0, 4irnsr,a~~t0ria "a rro coo itG•SYf.NDO APProrimdr c• /.2. •1:rLtIfO N'0r 6rovnd Line SCAL( IN 1`11T r 1 (L U.-____ tSl r/aC4 ST01ff9 Sy Lc Lrrtgf 0ire Atolls ACKhtT Itltel! ! JI O iRt Ri(hl 300' I of .S f 01 ,fill $21 -1- .18 SAN bliS >b o(DAm (f 64)17 Sit 0!170.3 (merle ncy It!/Dike NOIr: 4r6_ - 7.0 28 .19 it1 Is _ 10.0 _ II 170 Sh N00 ro5ti 11100 tt 664.3 y SpiBwsy A moimalr S/a.1000 to Imbonkmenti.lLf11 S I Dike DP f!0_ l.f ff to .19 efo Inver c tills. ry C.IS11/6!!0~ _ L~~ 200 If/ 6.t~ of jto two _ Appromendlrt7round[ine r e finerlrnry Rr(M D,ke No to! for 173 _ fJ9 iii- 0 I SDillnry CrH( Sec Non Appro[rmAh Sea 5010 to S/w 5130 !J 64.4.5 \ 1 e5 r b-etrnlrl/re t olOem fl Prinei r~f d/wa Gee [oft ~ Gerdr loDOl OrAr uniformly fi0m lL64j1 ©S1e SISO een cAenne levee 4VSAin its liri is ul the a"pen l^enl 4nUl to l.D'Ibore (/Jdr 0 Jpp/OLmrle Sh.bl00. le le In 41a0e ~pfOl'r f/rehvtll/t ilj.1 not etenyer then )I 060, to pecr':rlin Y LArp•! a D frr>G me ,I/a drtfl/rv.- AIf.O rn tAe Rslr/irllarmrn Dikf ! f/I be priced Ind paid tt the <Amvela Sviteple ercrula! eet4ri 41 q! be vet! A _ ' Lr,ncr nlioty~2 rH~l~ _ ltt.f opireenl re e.eclee a) inr (e Olnesr. Carl al IAre cArnnel as •CamplC/f sl 610 - l A'JA Ape eAfll be pelf a "preen CItnnel Ge4.- SrdimfaJ~/tre _61IJ 1' C ~/rf N(! Ares, .ACrN p JI diI oat,• nol.A.r. :e TYPICAL SECTION EMERGENCY SPILLWAY feQmrn/~ay~,4aryrr7 4_ cir Nero. Comp,'rle soil nd fop,rrdil;'en ~opluf~_ Jrr Srarf~(~A_7 Pre_ f r3f Uo --f- - krvrsf~sifian difi/edi/Ae~w~fA ATn L*i rru ,llwo~7i of ftt Appronmo If II, rb bAerafOry fetJ dill fveovra'rb'e Of Cu(Crf IYrnCA i., SCf fled Conelrvrl, on office 0 yarrenew Ay smipec wei d:ddrr9. NATIRIAL RLAC[YINT DATA 600CCMrf4NOr 6100 6100 10100 61100 I4ap0 pY6eHr aCet srL/rOr SOWLC Of fq.l ■ellr ►L Lrf t1N r(DVIRENNI6 tire. YDf,6K L41 PROFILE .)N OF OAM o.rA D4ea per Wn.u1 w Onn.p•e• uae,.er fee Dh Dr'a L" v e+ a Den YereI C. rs. M 0 6 IF.f 09.5 000f Any SeelioSerrrw / tt lls9 U.0 tOT.f t 11 Lfrrrrw 7 It III! 199 100.9 =J W!A'A Ito (tnty JpiPwvyCrra l f 639 . 0 I Ro hA L MIltrifl hom rtfyirtd tecrvlien may be wt/for'YOmpach/fiN 11 fma r Frw1 t Tell IACr npa r lienr09alremenle and hoe if 0 fp/e:eAtenl me toyer TYPICAL Piineips/Jlp illwlY Crd/f/ 61 f.! beln(Hr Hmelr fors/millor ma/rrv/ from ehe borrow arts. FLOODWATER RETARDING STRUCTURE t 12'be/m fl.62il.3 10'derm t/Hf.O ''r tP/iCtp'Ih1/'tr/e//iinulaMT/OT fine/~u7Cy Sppi/'w'i~/rln uPPJl/YSm btrm I ear the SA,.,r eemisoc1W tffoel is Ar rtedan d/rer,7 rolerfilt. GENEP.AL PLAN AND PROFILE Nr vpw~rd /%milf efp6eemenlrnvil/urs ..rt u!rA111Ard ripper U. S. DEPARnAENT OF AGRICULTURE /linih elploctmer7f marsl&/e acid be ro .111 rhol ooe n~ ernflirrJon BOIL OONSERVATION SERVICE 12' eyfhe r,; Slrreer Arse✓an 1754 r►aiidr.. rfPe[,at al/narLrirh A*)?e rnr S. Cedm {/3 of '10/7 fh0 /msiJrit 'elf relJed j-ti_..---...... _.._`?:ft ~c'all6D.Hl~ili..v,+•[.•-°' TYPICAL SECTION /.RUlmum drydenlily,op/lmvm molt Oere,minrmum recep lib/r dry dtneily and +r _D.f.f (IILC _-q-/t +elles"Gr1*11+111-------- meistvre ren(s ellown an ter mail per hewer Phi lin/ Mr number 4 Here, Alf G_. _ 11_•_66 EMBANKMENT DATA '1111 I_ C_tZ_-__,x-s~;~ 4•f•t9, •480 t' 53 [■c,v,h cprn chnnr/ home irbw - - ~ b n,lurs! drrn S/ppro// Sk )f 130, to be !~onl /.uc! (,r /h Fil! ylrmih poly„ '_°A,nne/ f,c•voliont ..awn /aa E/ bt/.1 A// le Or / e/rne/ •r •CompoeLd F!//! ov"nstrrr/e roe \ ~7op or 9ti /oar eI t Jerm DOm $14 r0000n t efLNnc,p,I SpOlw;ry rsr. lHOOon toro,m 251 4 - o /:o' M.0, terp,pe noes/ upslrrom foe PLAN e(efi/ Apr hr0' • G/O(mh%l Va besdod / Top of Dom El 6 ik l (Allowance %r oelllrrunl Included) Cott 1r~ 600 pro Js p6al piye lnpl1 ar L/CJaO'e 07 Cl piu b el o 1'uv dlamd, *0 liner me-! !/IwgCrosl Elwl.D TYPICAL SECTION p't1I' Nrir tm kA See Lk&/ M jI/N~ {of Dem BEDDING Anli-forli• COCA 12' Be rm Priori /SDrI/ww C//~,I fA see.! llstl f ____J1JIn1!- 7~ l12!1 S100~C.C, 14',4S00 T.O'princlpd Spi/lwvr Intel - A"CJM pit !!'Slide Cole /not f/Col.# App mole Gound lino SAO 1011 619.0 Sli, Hit t/s7 ().6170 . f4 plot (l6/f.S •f.urO /r for Csnd✓il four drtion w,hl S/• IN/ 1 ~ Jri Sl0i J!' 1'l Slde f/•pe, Ind It fl, iel/om width X090 p II. 609.0 ~ (A OIL! 4 (pipproriM406limi6 ,howo,rhdireA- (111 prior b r.urOlin/ [u le!/ lrencA. \1 e'. 1000 Ceie: f•Cavlli Cula/f liencA fseavolion h Ae ppro,d Oo rCuloff rrrerh w!!A / Sidi VveS And 17 It p0//OM wid/n t o 1/LIIIliOn!&Of*611 N Mppid eS h o'/~a•imile AM,/Shown On 'A"'Ohle en IF { i 'GmpOrir/ fill'. e✓OOm.' a (SOA'er/J'DbS Type Z, Class ?418 NLr,LdrOnieed~c/o,r rireled iiluIn &I, C"Ird OSialoS Dendrd f,p,o Je eorru(.hd JAeolmdi/pipe,wNh Spec/&/ WO/pr li`'A!fond touplrrSl I-0', /Orhrelin/e/Ond !-10. Srclion-0 TYPICAL SECTION FLOODWATER RETARDING STRUCTURE PRINCIPAL SPILLWAY STRUCTURE PLAN A140 SECTION U. S. DEPARThUENT OF AGRICULTURE SOU, CONSERVATION SERVI L [.eoff C--1061 -R.i C. 11-N - i 4-E-19,400 54 f t 570 , J - IqUI Imp, h _ 00, t-T _T j 90 560 0 W }t LLJ WITH PROJECT - ELEV. 563.2 550 - I Iflit t -11 lit q- -1 11 0+00 5+00 10+00 15+00 20+00 25+00 30+00 ' Fi 9u re 3 DEGREE OF FLOOD PROTECTION HICKORY CREEK WATERSHED (VALLEY SECTION 5) TRINITY RIVER WATERSHED, TEXAS STORM OF MAY 29-30f 1946 2.56" RAINFALL WITH 2.03" RUNOFF APPROXIMATELY 2-TEAR FREQUENCY U. S. DPAPTAIENT Of AGRICULTURE, SOIL CONSERVATION SERVICE, TENfLE, Tf AAS 0906us6mmr mono. red 11,4110 A•i/R OS TI.fO r 55 1 r I WV YI' Yy, r ' _ ,FRn~}~./~'I..~}~ Ilr ftl' 4 a 'x , ' I r ,l~'1 ~ f S ~ t I. Y LEGEND r ~ ~ ~ 4,+ , r . v ~~t ' ~ . \ • I ~ .1 X71 r ]k Ry Expected Flood Line of 100-year Frequency Flood Without Project • rm-waft nd QiLm 1 nr nfinn I r ^ , I, • y ra 1 ~ \I'rV ~ Ali n ~ r ~ 1~y *rr 1 , ti, 1R ~r~ Y A. r,. ~ ~V ,~`{w, rfM ` / MY 1t~ t.' 1 t T C r 1\ ;A~ ~ x~+y •~x~" ~Aa !'~"l.?~~' f r d ~1 ~1~7, ~~Iii iv ~ a. y ~{,~y .r e. r ~~I~ I ~s~Y ~ r v ~ ~ r~ ~ I ~ / ~.,.r-► Pecan Creek Channel Through Denton t l-] jy~ 1 ~ ur+r r,• ~ ~ '~f ~ I 1 1 1 /,n l ry,. I 41A .0 t M , •wY ~ ~ d4 ,.tr ~ ~ ~ .7 d ~ R . d ~ t► c ie i4 7 ~tt* ~4. `.~T+~.'S~d a^ l I' l ~ ~ 1 r opt ~ ~~a' r/. ~ • APGRSl MATE SCALE IS MILES 44, r r 1 4k 1 I .1 ''r rr~ ~ ~r• r FI vro i :t URBAN BENEFIT ARIA r t~• I ~y~,~~ DENTDN, TEXAS i ' ~r r , ~a~ I ~ • I PECAN CREEK LAtERAI OF HICKORY C a U. S. DEPARTMENT OF AGRICUII SOIL CONSERVATION SERI r v, ~ TEMPLE. TEXAS Ai a 'd' ~ - A 1~ Se~re~1~r196F l-tioq r-4r i i m 1 r r - h LEG: N D ' Paved Road Improved Rood Proposed Rood Railroad ~a✓ W Levu Drainage ' d LOVor Pond r ; County Line I i Town or City School ~a i~ i Church i Cemetery + PI ah f Watershed Boundary p v op l;:.,.... Dotline of Floodwater Sediment 'u and Scour Damage Sediment Damage SSSSSS Scour Domogs volley cross Section r v c~ , Evoluation Ruch ' • d r ~ rII r ;I ~'S~^6 1 6 ~ / N X18 s I / FI h t ( r 7r + p r 5 F ' ( uo Read F J rt ; f- . 1 f r D Y N- ( Q ~L f t t ' rnR w+v w l 1 1 57 LEGEND SITE NUMKRS B DRAINAGE AREA No. Aaos Paved Rood I 32001 0 Improved Rooa 2 1549v~ Proposed Rood 3 6963 Rodroad 5 416 6 2042 ~ Drainage 7 S86 i b IVt Lake or Pond 9 209J County Line 10 I I84 Torn of City 12 690 Gry eL SC 1 _ 3 ~ 7 I i Church 14 1650 '*H' Cemetery 15 969 Al f~?16 1062 v watershed Boundary 17 659 C~ Floodwatu Retarding Structure 'tii4"h Drainage Area Gont10111d J ,.ir k4)' l i li~~~ _.~~f ~fWW~ ♦.Pay by Structure Ile Beneided Area r t : Structure SdI Number T li del\ J~ 4 a ♦ . , Ali y 1 Y 4 - ~4'~ rf~ V r a K r~ ] 1 1 I_