5.8.4 Auburn Lake Internal Load Management Project

ProjectAuburn East Lake Internal Load Management Project
DescriptionDesign and implementation of strategies to reduce internal phosphorus loading, including: feasibility study; aquatic vegetation survey update and management plan; fishery survey update and management plan; biomanipulation strategies that may include aquatic vegetation management, zooplankton community and fishery manipulation, and chemical treatment
Need

The modeled watershed phosphorus wash-off load to East and West Auburn Lakes is not sufficient to explain the in-lake concentration of total phosphorus that exceeds the lakes’ total phosphorus goals. An “unknown load” is attributed to internal loading, and is likely a combination of bottom sediments, aquatic vegetation, and model accuracy. A watershed and lake diagnostic / feasibility study will be required to confirm the internal and external phosphorous loading to the lakes, as well as the necessary load reductions. In particular, the “unknown load” must be identified as either an external or internal load before specific strategies can be selected. A variety of strategies would be investigated in the diagnostic and treatment study proposed in this plan.

This project would identify and implement a suite of strategies to manage aquatic vegetation, the fishery, and zooplankton community to achieve water quality and clarity goals. Because Auburn East discharges directly to Auburn West, both lakes should be investigated at the same time. The project includes an ongoing vegetation and fishery management plan. Management of invasive aquatic vegetation that contributes to lake water quality and usability issues would require annual treatment for three to five years.

OutcomeReduction in phosphorus load from internal sources estimated at 284 pounds annually in Auburn East and 187 pounds annually in Auburn West; improved water clarity; more diverse aquatic vegetation community; improved aesthetics.
Estimated Cost and Funding
Investigation, permitting, fish, vegetation, and
zooplankton surveys, and implementation of
strategies. Funding source is the District capital
levy.

$17,600 Design, survey

$169,700 Construction

$187,300 Total

Schedule

2011 Design, acquire easements

2012 Construction