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2018-132 Lake Forest Park Retention PondDate: September 21, 2018 Report No. 2018-132 INFORMAL STAFF REPORT TO MAYOR AND CITY COUNCIL SUBJECT: Lake Forest Park Retention Pond BACKGROUND: Lake Forest pond is approximately 10 acres located within Lake Forest Park. This body of water serves not only as drainage retention but also as a water feature for the surrounding park and the Good Samaritan Society – Lake Forest Village. DISCUSSION: Lake Forest Park is a 69.32 acre park with a lake, playground, trails and open green space. The park is also home to Wiggly Field Dog Park. The City of Denton has owned the park land since December of 2002 and have made many improvements over the years. Restoration and dredging of the pond was proposed to the 2014 bond program for over $1M but not funded for unknown reasons. It appears that the siltation of the pond has progressively worsened over the years. An attached PowerPoint of google images provides a history of the pond since 2001. In September of 2017, Teague Nall and Perkins was hired to complete a dam conditions assessment and hydrologic study for the Fletcher Branch Tributary 4, otherwise known as “Lake Forest Pond”. Currently, the study is in the process of finishing the soil samples within the dam to determine its condition. A draft of the study should be submitted to the City in October 2018. Over the course of the last 4-5 months, staff has had a number of conversation and meetings with residents and board members from Good Samaritan Society Lake Forest Village regarding this challenge. Parks and Recreation along with Engineering are working on a number of short-term and long- term initiatives to help solve the problem. These include but are not necessarily limited to:  In August 2018, PARD submitted an application to the Texas Parks and Wildlife Department to place sterile carp in the pond. The carp will help control and remove the existing aquatic vegetation. This application is a six week process and expected to be returned by the end of September.  Recently, staff from Parks and Recreation and Engineering had a conference call with a consultant from a local engineering firm to provide support for interim measurements to help deal with the challenge to improve water quality and reduction of vegetation within the pond. Date: September 21, 2018 Report No. 2018-132  PARD is researching the purchase of bubblers/fountains to place in the pond to help with water movement.  Engineering is looking into installing check dams up from the pond to capture sediment from development before entering the pond.  PARD is in the process of meeting with contractors/distributors for aquatic vegetation removal machinery. This will be for the possible purchase of maintenance equipment or contracting of the vegetation removal.  In the spring of 2019, PARD plans on placing Tilapia in the pond to control the algae. Tilapia often die in cold weather conditions, therefore this is why the installation of these fish is delayed until next spring. Pending the result of the TNP study on the dam and possible dredging and/or repairs, it is anticipated that the cost of this pond improvement will be substantial. While cost is undetermined at this time, the request made in the planning for the 2014 bond program was for $1,085,000. In addition to any repairs and dredging, property to the east of Lake Forest Park is going to be under construction in the near future, in addition the property west of the park is also under construction. This could result in continued filtration of sediment into the retention pond at Lake Forest Park STAFF CONTACT: Drew Huffman Superintendent Parks and Recreation Drew.Huffman@cityofdenton.com 940-349-7464 LAKE FOREST RETENTION POND •The following pictures illustrate the changes of the pond from 2001 –2018 •Survey of the property •Depths of the water taken on September 7, 2018 FEBRUARY 2001 OCTOBER 2005 OCTOBER 2007 OCTOBER 2008 OCTOBER 2014 SEPTEMBER 2017 MARCH 2018 Depths of water taken September 2018