Monitoring plan drafted for Tahoe’s nearshore
February 10, 2014
Regulatory agencies are taking public comments and putting the finishing touches on a draft nearshore water quality protection plan for Lake Tahoe.
The plan doesn't make new regulations or standards. Instead, it charts a path to better monitor key water quality and ecological indicators in an area of the lake extending from shoreline to a depth of 69 feet or a distance of 350 feet, whichever is greater.
At a public workshop Jan. 30, researchers described the nearshore as a complex, dynamic and relatively little-studied environment with wide variations around the lake.
Water quality assessment at Lake Tahoe historically has focused on clarity of deeper, mid-lake water, researchers said. But most people experience the lake in nearshore waters that apparently have been deteriorating.
"We've heard testimonials about people who go to the same places every year and say rocks are getting slimier, water murkier, and more recently, reporting aquatic invasive species," said Jason Kuchnicki, of Nevada Department of Environmental Protection.
The plan follows a Nearshore Evaluation and Monitoring Framework Report released in October by Desert Research Institute, University of California, Davis, and University of Nevada, Reno.
It goes to Lahontan Regional Water Quality Control Board for consideration next week and is slated to be sent to the California State Legislature in March as required by a 2012 budget bill.
The goal is a better understanding of Lake Tahoe's nearshore and more robust data to assess its health and guide policy.
Proposed monitoring would regularly assess water clarity, trophic status and the integrity of biological communities.
Agencies would do turbidity and transmissivity testing around the lake to assess water clarity, measure chlorophyll and algae levels to assess the lake's trophic status, or fertility, and assess populations of vascular plants, macroinvertebrates, fish and crayfish.
Proposed monitoring integrates with other monitoring efforts as well as existing programs and regulations that should help improve nearshore waters, said Dan Sussman, an environmental scientist at Lahontan Regional Water Quality Control Board.
That includes targeted pollutant reductions through a Total Maximum Daily Loads program, boat checks for aquatic invasive species and efforts to reduce vehicle- and fertilizer-use to cut the amount of algae-inducing nitrogen and phosphorus entering Lake Tahoe.
Some monitoring already is underway, but the plan calls for it to be expanded with studies to investigate nearshore problem areas starting in 2015.
One area tentatively set to be investigated is the lake's northwest corner, where attached algae on rocks and other structures, called periphyton, has been a regular problem, Sussman said.
Distinguishing between controllable, human-induced nearshore problems and natural conditions and triggers such as drought will be a challenge, he added.
The plan also would try to identify climate change's influence on the nearshore because shallower, warmer water promotes algae growth and success of non-native warm water fish species.
"We'll try to tease out what changes are happening and use resources on controls with better chances of being effective that won't be bowled over by climate change," Sussman said.
The initiative's success is expected to depend in part on funding, at least some of which has not yet been identified. "For the (monitoring) framework the report put forward is somewhere around $450,000 annually," he said.
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