There have been many environmental efforts to help keep Lake Tahoe blue over the last few decades, from stormwater treatments to the banning of two stroke engines. It’s long been known that road runoff is the last remaining big culprit.
In order to better understand what causes the loss of clarity in the lake and help reinstate it, those charged with helping protect the lake have created a science based plan called the TMDL, Lake Tahoe Total Maximum Daily Load. The plan seeks to guide the effective implementation of the TMDL so that people may once again be able to see to depths of nearly 100 feet in Lake Tahoe.
Road sand and dust are the primary sources of fine sediment in stormwater runoff flowing into Lake Tahoe, according to a recent TMDL report. On an average, 12,000 metric tons of traction abrasives are applied to Tahoe area roads annually. The road sand gets pulverized by vehicles, resulting in 300 metric tons of airborne pollutants.
But road sand isn’t the only culprit adding to detrimental road runoff. Road shoulder and road cut-slope erosion, abrasion of the roadway itself and car tire
degradation also add to the problem.
The study showed that frequent roadway sweeping with a high efficiency vacuum assisted sweeper significantly reduces the roadway runoff. This, combined with anti-icing pretreatment, is proven to be economically effective.
According to the report, all types of stormwater treatment BMPs suffer from insufficient maintenance: vegetated swales, sediment traps, dry basins, wet basins, cartridge filters, and treatment vaults. This includes private BMPs (residential and commercial) as well as at the public level (roadways and facilities).
One of the top priorities for The League to Save Lake Tahoe for the past decade, and continuing into 2015, is to evaluate and ensure that the newly implemented Lake Tahoe Total Maximum Daily Load program is effective in reducing pollutants to Lake Tahoe. “This report shows there’s a huge opportunity to reduce sediment flowing into Lake Tahoe simply by improving the management of our street sweeping and road sanding operations,” said Darcie Goodman Collins.