By Kathryn Reed

“It’s about finding opportunities and doing the work we know needs to be done.”

This is how Bob Larsen with the Lahontan Regional Water Quality Control Board summarized the ongoing efforts to reduce the pollutants reaching Lake Tahoe. Much of that is fine sediment that is washed into the lake, which then degrades the clarity of the water.

His agency along with the Nevada Division of Environmental Protection are the overseers of the total maximum daily load program in the basin. Goals are set for each government jurisdiction in Tahoe – from the city to the counties, state departments of transportation, U.S. Forest Service and state land owners.

The 2017 performance report was released Aug. 17.

“Exceeding the target was expected based on the work done,” Larsen told Lake Tahoe News.

The five-year goal was to reduce sediment reaching the lake by 10 percent. Collectively, there was a 12 percent reduction from the 2004 base year. (The TMDL program started in 2011.) In the process, the amount of phosphorus reaching the lake decreased by 8.5 percent and nitrogen by 6 percent.

The sediment reduction equates to 268,500 pounds or 70 dump trucks worth of fine dirt that have been keep from the water.

In the spring, South Lake Tahoe, El Dorado County and Placer County were notified they met their goals. The next five-year goal for each is reducing pollutant loads by another 15 percent.

Throughout the basin the next five-year goal is another 11 percent reduction on top of the last 10 percent goal.

“It will be a challenge, but I feel it’s a challenge we can overcome,” Larsen said.

Runoff from roads is a primary source of sediment reaching the lake. The worst roads, according to officials, mean more gunk going into the water.

“There is some new information we have showing roads contribute upward of 30 percent of the sediment into the lake,” Russ Wigart with El Dorado County said last spring.

Different surface materials are being studied and various catch basins installed.

The long-term goal of the TMDL is to restore the lake’s clarity to 97.4 feet by 2076. This means when scientists put what looks like a white dinner plate into the water it will be able to be seen by the naked eye to that depth.

In 2016 the average depth of clarity was 69.2 feet. Sixty-four feet is the worst it’s been. That was recorded in 1997; the same year as the first environmental summit at Lake Tahoe. Since that time about $2 billion worth of environmental improvement projects have been implemented in the basin, all with the ultimate goal of protecting Lake Tahoe.

Other factors besides sediment are contributing to the clarity loss-gain. Climate change is a biggie, according to scientists. Time will tell if the millions of dollars spent each year on these TMDL projects will be enough to keep Tahoe blue and not have it look brown like so many lakes in the world.