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5.8.4 Tanager Lake Improvement Ponds

ProjectRegional Pond at LLC-51
DescriptionConstruction of a regional stormwater detention pond to treat stormwater from a subwatershed unit exporting significant phosphorus load to Tanager Lake.

The phosphorus reduction plan for Tanager Lake requires a reduction of 868 pounds of phosphorus per year, including both external sources of phosphorus and internal sources. A detailed investigation of the source of excess loads in Tanager Lake will be necessary to identify options for management of its internal load, including an investigation of the source of increases in phosphorus and TSS loads in Long Lake Creek from upstream to downstream. Improvements to Long Lake Creek and the riparian wetlands through which it flows may reduce that loading to the lake and provide the opportunity to improve habitat, stabilize banks, and address low-flow dissolved oxygen issues.

Phase I of this project includes a diagnostic study to refine the water quality model to better understand and partition external sources and internal sources. Phase II includes the construction of a wet detention pond in subwatershed unit LLC-51, to treat subwatershed higher than average phosphorus load being contributed to Tanager Lake, helping to achieve the external phosphorus load reduction goal for this lake. The diagnostic may identify additional wetland or stream restoration projects that may provide an opportunity to reduce external phosphorus loads.

OutcomeThese ponds could remove an estimated 23 pounds of phosphorus annually, along with other pollutants such as sediment.
Estimated Cost
Investigation, permitting, easement acquisition,
construction, and project management. Funding
source is the District capital levy.

$65,500 Design, easmnt

$410,400 Construction

$475,800 Total


2012 Diagnostic study, design, easement acquisition

2013 Construction