Saturday, September 29, 2007

Lahontan and sediment in Lake Tahoe

unedited Tahoe Mt. News Sept. story

By Kathryn Reed

Two reports coming out this month from Lahontan Water Quality Control Board are designed to be the building blocks for keeping sediment out of Lake Tahoe and helping restore clarity to a depth of 100 feet.
UC Davis this summer in its inaugural “Tahoe: State of the Lake Report 2007” pointed to climate change as being a significant reason the white plate-like Secchi disk is less visible than in years past. In 2006, it could be seen at 67.7.
More precipitation creates more erosion or runoff of fine particles into the streams that flow into the Lake. This could explain why in 2006 clarity dropped more than five feet from the previous year. The amount of precipitation that year was 84 percent more than the average between 2001-05.
Lahontan released a draft of the total maximum daily load report in August 2006. The final is one of the documents coming out this month. It includes all the science that explains the problem. The water board’s other report deals with ways to solve the problem.
Both will be the focus of three daylong meetings as part of the Tahoe Regional Planning Agency’s Pathway 2007 Forum. The first is Sept. 27 at Lake Tahoe Community College, then Oct. 25 at the North Tahoe Conference Center in Kings Beach and the third Dec. 6 at LTCC. All are from 9 a.m. to 4 p.m.
A wrap-up meeting is tentatively scheduled for February. People wanting to relay comments to P-07 members may do so via
The first meeting will give an overview of the issue, how fine particles are the main culprit to declining Lake clarity, with the scientific evidence to back up that statement. The latter meetings will focus on what people want to do about it and how to accomplish those goals.
“We are launching the public process to formulate an implementation plan to restore Lake Tahoe. We want to engage the general public and those tasked with having to do it,” is how Lahontan division manager Lauri Kemper described the purpose of the fall meetings. “We don’t care which way we get there. We just care about load reductions. We are producing the science and tools to evaluate those choices.”
Reducing particles into Tahoe isn’t something agencies in the basin thought up. This is a mandate from the Environmental Protection Agency that is part of the Clean Water Act.
What comes of this will, however, be incorporated into TRPA’s next regional plan which is expected to be adopted in late 2008 and be a working document the next year. Both states must approve the plan before it goes to EPA headquarters for the final OK. That is expected to happen in 2010.
Despite the lengthy review process, it doesn’t mean things are at a standstill. Caltrans and the Nevada Department of Transportation have done stormwater runoff research which is being incorporated into their projects. Kemper said projects her department oversees must use the most up-to-date technical and design standards.
“Fine particles was the big emphasis last year. That shifted individual project design,” the engineer said.
South Lake Tahoe is working on reducing sediments thought its rock project in Sierra tract, two basins on Eloise Avenue and the Industrial tract project.
Lahontan is looking at its sediment and fuel reduction regulations. Mechanized equipment can be used on dry soil, driving on slash piles may be an option, leaving woodchips, repairing trails for proper drainage and getting rid of unnecessary roads are options, according to Kemper.
“Now we have more information, science and tools to evaluate our decisions,” Kemper said.
Reducing how much particle matter goes into Tahoe is close to a billion dollar endeavor when all the studies and Environmental Improvement Projects are tallied.
“I think it’s worth it because the Lake is a unique resource and international treasure. If we lose it, it’s difficult to regain it. It’s a public decision,” Kemper said. “We hope the public will see the difference their choices make.”

Breakout box:

The annual average Secchi measurements for the past several years:
1968: 102.4 feet (first year measured)
1997: 64 feet (worst year)
2000: 67.3 feet
2001: 73.6 feet
2002: 78 feet
2003: 71 feet
2004: 73.6 feet
2005: 72.4 feet
2006: 67.7 feet

Source: UC Davis

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