Wirth Lake Outlet
Wirth Lake is located in Theodore Wirth Regional Park in the City of Golden Valley. The lake was listed as Impaired due to excessive phosphorus levels. In recent years water quality goals were met except during instances where seasonal overflows from Bassett Creek into Wirth Lake occurred.With one relatively simple project, the Bassett Creek Watershed Management Commission anticipates that the excess phosphorus problem will be resolved once and for all. The Implementation Plan for the Wirth Lake TMDL includes modifying the outlet structure to prevent flow from the creek to the lake during flood periods. Based on an analysis of historical data, the modification of the Wirth Lake outlet will achieve reductions in phosphorus sufficient to meet water quality goals.The modifications include replacing the existing bulkhead in the outlet structure with a fabricated steel lift gate. The lift gate would be operated with an electric motor and controls that would operate based on water levels in the creek. The gate would close during periods when water levels in the creek would result in backflows to Wirth Lake.The estimated cost of the steel lift gate is $80,000 and the cost of the controls is estimated to be $70,000. The total estimated capital construction cost to modify the Wirth Lake outlet and install the gate and controls is $250,000 including administration, permitting, and installation. With the $75,000 Clean Water fund grant, Wirth Lake will meet water quality goals and park users will see increased water clarity.
Nicole Clapp
(b) $2,800,000 the first year and $3,124,000 the second year are for grants to watershed districts and watershed management organizations for: (i) structural or vegetative management practices that reduce storm water runoff from developed or disturbed lands to reduce the movement of sediment, nutrients, and pollutants or to leverage federal funds for restoration, protection, or enhancement of water quality in lakes, rivers, and streams and to protect groundwater and drinking water; and (ii) the installation of proven and effective water retention practices including, but not limited to, rain gardens and other vegetated infiltration basins and sediment control basins in order to keep water on the land. The projects must be of long-lasting public benefit, include a local match, and be consistent with TMDL implementation plans or local water management plans. Watershed district and watershed management organization staff and administration may be used for local match. Priority may be given to school projects that can be used to demonstrate water retention practices. Up to five percent may be used for administering the grants. (2011 - Runoff Reduction)
Wirth Lake will meet water quality goals and park users will see increased water clarity.
The project involved installation of a new concrete lake outlet structure consisting of two rubber check valves, rather than an electric lift gate, which prevent an average of 55 pounds per year of phosphorus from entering Wirth Lake via backflow from Bassett Creek.