With many county projects already reducing the amount of pollution entering Lake Tahoe, the Placer County Board of Supervisors today approved a plan that will continue efforts to maintain and improve the lake’s clarity. The plan is required under a recently updated federal permit that was issued by the state Lahontan Regional Water Quality Control Board, regulating storm water runoff from the three California jurisdictions at Lake Tahoe: El Dorado County, the city of South Lake Tahoe and Placer County.
The first permit for the California side of the lake was issued in 1992. Since then it has been renewed several times with increasingly stringent requirements for the reduction of pollutants entering the lake. The plan approved today includes actions proposed through the current permit term, extending to 2016. The county contracted with the U.S. Army Corps of Engineers to develop a strategy to achieve a reduction in three key pollutants: fine sediment, nitrogen and phosphorus. The maximum amount of these pollutants that can enter the lake was established and will be tracked annually. The necessary reductions needed to improve Lake Tahoe’s clarity are described in the permit.
Fine sediment comes from dirt and sand that mix with rain and snow to form polluted runoff that can reach the lake. Nitrogen and phosphorus are typically found in fertilizers that are used to green-up landscaping during the relatively short growing season at the lake.
Over the last decade, Placer County has completed 16 water quality improvement projects that have reduced the amount of pollution reaching the lake. In addition, there are six more projects in varying stages of completion that will further reduce pollution.
“The problem of too many fines reaching the waters of Lake Tahoe has been ongoing for decades,” said Supervisor Jennifer Montgomery, whose Fifth District includes the Placer County portion of Lake Tahoe. “The approval today of this plan gives us specific goals for pollutant reduction. Attaining these goals will take work, but that is necessary to not only stop the decline in the lake’s clarity, but to improve it as well.”
Two of the proposed sediment reduction projects are the Kings Beach Commercial Core Improvement Project and the Lake Forest Panorama Project which, when completed, will prevent nearly 17,000 pounds of pollutants from entering the lake each year. These two projects will treat runoff that flows either directly to Lake Tahoe or into streams that reach the lake.
In addition to the water quality projects, Placer County is taking other measures to reduce pollution. Each winter, crews from the county’s Department of Public Works plow snow and spread abrasive material on roads to improve vehicle traction. A study conducted by the California Department of Transportation (Caltrans) showed that by simply switching to abrasive sand with a lower percentage of fine sediment, the county can reduce the amount of fine sediment reaching the lake by nearly 5,000 pounds annually.
Placer County is also purchasing a high-efficiency sweeper to further control where sand and other sediment end up. The new vacuum -assisted sweeper will be used more frequently in winter and summer months to remove pollutants from roadways, before they are carried away by rain, snow or wind to the lake. Depending on how the first high-efficiency sweeper works out, the county may add a second unit to the county’s fleet.
The county can directly control water quality improvement projects managed by its Department of Public Works to maximize pollution reduction benefits. Additionally, by requiring that any new development or redevelopment of private property apply best management practices to reduce pollution potential, further benefit to improving lake clarity will be realized.