Groups working to clarify stormwater
April 19, 2014
The League to Save Lake Tahoe focused on ways to reduce the amount of stormwater pollution entering the lake.
There's a lot that government agencies in the basin are doing and there's a lot people can do to help, said Jesse Patterson, deputy director of the League to Save Lake Tahoe.
Tiny sediment particles smaller than the width of a human hair are one of the biggest drivers of Lake Tahoe's clarity loss. Pulverized in parking lots and roadways, about 70 percent of the hundreds of quintillions of ultra-fine particles estimated to find their way into the lake in an average year wash in with stormwater from roads and urban areas.
Once in the lake, particles stay suspended in the water and scatter light, reducing visibility.
Keeping those particles and other contaminants out of Lake Tahoe, such as nitrogen and phosphorus, which fuel algae growth, is the main goal of a Total Maximum Daily Load program created to restore the lake's clarity, said Robert Larsen, the senior environmental scientist for Lahontan Regional Water Quality Control Board.
Adopted in 2011, the program requires jurisdictions such as Caltrans, Nevada Department of Transportation, the city of South Lake Tahoe and El Dorado, Douglas, Placer and Washoe counties to reduce their stormwater pollutant loads.
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A "clarity challenge" directs jurisdictions to cut stormwater pollutant loads by 34 percent over 15 years and by 70 percent over 65 years. The goal is to restore mid-lake clarity levels that measured nearly 100 feet in the 1960s and now measure just 60 to 70 feet on average.
"Because urban stormwater is such a big deal, basically reducing the basin-wide loads by about a third we believe we can halt clarity decline and start restoration, turn the corner and start to move the graph in the other direction," Larsen said.
As jurisdictions work to meet their targets with often-costly projects to capture and then either infiltrate into the soil or treat stormwater, Tahoe Resource Conservation District is leading efforts to develop a Regional Stormwater Monitoring Program.
Advanced sampling machines at select stormwater outfalls will collect data to determine if projects are actually reducing pollution loads as expected and what type of mitigation projects are most effective. Monitoring will also look at the effectiveness of various best management practices Tahoe Regional Planning Agency requires property owners to install.
While government agencies are doing what they can to reduce stormwater pollution, there's no shortage of things individuals can do to help, said Russell Wigart, an employee in El Dorado County's transportation department and a volunteer in the League to Save Lake Tahoe's pipe keeper program.
One thing people can do is join pipe keepers, Wigart said. Volunteers with the program help keep tabs on the quality of water coming out of stormwater outfalls around the lake, venturing out during rain events to collect samples for testing. With the rain season coming to a close, volunteers will soon be going out to mark storm drains to help let people know that they drain into the lake, not into the sanitary sewer system.
People can install and maintain best management practices to reduce storm water runoff at their home or business, replace the turf in their yards with native vegetation and not use or over-apply fertilizers. Even something as simple as using less ice melt or picking up pet waste makes a difference, Wigart said.