Tahoe shoreline troubles a mystery to scientists
By Kathryn Reed
It doesn’t take science for people to know Lake Tahoe’s shoreline is growing as the drought persists. But it does take science to determine the health of those waters.
The annual “Tahoe: State of the Lake Report 2014” was released today by the Tahoe Environmental Research Center at UC Davis.
“While this year’s data shows that progress is being made on many fronts, the biggest concern is what is not able to be shown,” TERC Director Geoff Schladow said in a statement Aug. 14. “This really applies to the near shore where most people experience the lake. Even with the planned increase in monitoring, why it is continuing to degrade is poorly understood. I’m hoping the near shore network will start to fill that void.”
Emerald Bay and Lake Tahoe in April 2013. Photo/LTN file
The Near Shore Agency Working Group is tasked with figuring out why there is so much muck near the shore line. Algae and other plant life have been steadily growing, and the once clear waters are often brown. Periphyton is the algae found on rocks.
It wasn’t until this year that scientists in the respective agencies that regulate and study Lake Tahoe decided to make a concerted effort to find out why the degradation is occurring and what can done about it. The first six of 20 near shore monitoring stations will be installed this month. This will give researchers real-time data about water quality. They will be installed on private and public property.
Most of the studies that have been conducted at Lake Tahoe since 1968 involve monitoring the clarity in the middle of the lake with a disc that looks like a white dinner plate. While some of that data will help with near shore issues, most of it won’t.
The good thing about a drought is that it means less sediment reaching the lake from runoff. It’s fine sediment that scientists say is the leading cause of the decline of lake clarity.
The current State of the Lake Report explains how drought, climate change, and other natural and human factors are driving changes at Lake Tahoe.
2013 was the second consecutive year Lake Tahoe did not mix to its full depth. The lack of mixing was because surface temperatures were higher.
July 2013’s surface temp of 65.6 degrees was the highest recorded in five years. This was 1.8 degrees more than 2012.
The loss of near shore clarity and rising temperatures creates a breeding ground for invasive species.
Alan Heyvaert, an associate research professor and director of the Center for Watersheds and Environmental Sustainability at the Desert Research Institute, is leading a group of researchers studying the near shore.
UNR and DRI researchers have installed cameras on mountaintops that in part are being used to study the near shore. They have documented a 90 percent decline in small species that live in the sand at the bottom of the lake – stoneflies, worms and bottom shrimp. Those species are important to the lake’s food chain.
But also alarming is the discovery of new species.
“Changes in the length of seasons will alter the way in which water moves in the lake, leading to the possible loss of dissolved oxygen at the bottom of the lake,” the State of the Lake Report says.
This in turn will also change the ecosystem because the chemical balance in the lake will be altered. This, too, will affect aquatic life.
Researchers are predicting that by the end of this century, summer may be two months longer than it was in the 1960s, and maximum temperatures may have risen by 8 degrees.
“With regard to climate change, we have really only scratched the surface,” Schladow said. “We have little understanding of how extreme events will play out and impact the Tahoe basin and the Sierra.”
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Notes:
• Tahoe Environmental Research Center Director Geoff Schladow will present highlights from “Tahoe: State of the Lake 2014” on Aug. 14 from 5:30-7:30pm at TERC, 291 Country Club Drive, Incline Village.
• Here is the full report.
“The Near Shore Agency Working Group is tasked with figuring out why there is so much muck near the shore line. Algae and other plant life have been steadily growing, and the once clear waters are often brown. It wasn’t until this year that scientists in the respective agencies that regulate and study Lake Tahoe decided to make a concerted effort to find out why the degradation is occurring and what can done about it.”
Glad their finally going to start addressing this. I agree that the near shore is from where most people experience the lake and wonder why it’s taken so long for the “respective agencies” to finally start focusing on this problem.
I attempted to contact Professor Schladow last year regarding some clarification of issues associated with urban runoff and lake clarity. I told him I was concerned because of the dramatic cutback TRPA had imposed on the residential building allocations.
In 2013 TRPA had been openly bragging how their environmental effortss dramatically enhanced Tahoe’s clarity – and with information reported by Professor Schladow.
At the same time TRPA lumped residential runoff with all other urban runoff attempting to make it appear residential construction was a huge contributor and justifying the 65% cutback in residential allocations per year. In fact residential construction is nearly insignificant in comparison to all the other contributors in urban runoff. TRPA falsified the truth to leverage the residential cutback.
The fact that Professor Schladow refused to address my request for urban runoff clarification indicates to me he works for TRPA. He carefully times and words his reports in collaboration with TRPA to justify their survival as necessary environmental agencies.
Here’s a thought: The South Shore has some of the shallowest shoreline around the lake. Add to that the largest body of standing water (the Keys) around The Lake. Add to that the prevailing winds blow from the North-northwest to the South Shore. Then add to that the largest inflow of runoff comes into the lake via the South Shore river and stream zones. Not to mention the largest amount of fertilized grass fields/golf courses around The Lake.
Here’s a question: Is their anywhere else around The Lake with the amount of algae growth and invasive shellfish species flourishing?
Just the observations of an uneducated long time local.
‘why it’s taken so long for the “respective agencies” to finally start focusing on this problem.’
Policy brings up new questions, and the science informs policy.
There are some studies about currents in Tahoe, the methods they used are really neat. The study of the near shore was not as neglected as some suggest. Clarity is a really good overall indicator for the health of an oligotrophic lake and it is best measured in water that is too deep to be ‘near shore’. It might make more sense to understand more about the deep water before spending too much effort on the shore.
‘The fact that Professor Schladow refused to address my request for urban runoff clarification indicates to me he works for TRPA’
I wonder why a scientist wouldn’t respond to you…
It doesn’t take a scientific report and agency action to correct something that has happened before when the lake is low.
Anyone remember the algae and smell at the shore back in 1978-1979 when we had a drought ?
I do, and it was much worse than it is now. Gosh, somehow when the cycle changed and the lake filled it all resolved ……… hmmmmm
It’s like “the little boy that cried wolf” but in this case it’s for another new agency program.
There is Schladow again telling us how little science knows about the lakes biology at the same time telling us about variables known and unknown.
The so-called scientists don’t know with any degree of certainty how to compensate or overcome these natural and unnatural processes but with a billion dollars up for grabs they will surely grovel to get some of it.
They are doing a fabulous job of covering their butts with their excuses as why the corrective expensive projects to increase lake clarity are failing.
More welfare in the name of science and politics.
As the lake drops due to drought, the shoreline actually shrinks, not grows as your first sentence indicates.
So, the algae and weeds etc get pushed into a smaller area, and bottom growth gets further exposed by the dropping/shrinking water surface. It becomes more noticeable, and exposure to air and sun begins a decomposition process with smells etc.
Low water always exposes the shore/water interface to a greater degree.
It really needs to be understood that Lake Tahoe will, (without some significant geological or morphological event(s) that change the drainage patterns), eventually be a flat, peat filled soggy, alpine meadow like Grass Lake at the top of Luther pass on Hwy 89.
TRPA can make a case that they may have slowed this development in a miniscule way, but even this all powerful and dedicated Agency cannot stop this natural process.
Um Observer. All Lakes “eventually” fill in. Lake Tahoe will become a meadow in about 3 to 4 Million Years. Keep in mind that 4 Million years ago our ancestors were Australopitheci from Africa. If Homo Sapiens are around in 4 Million years, they may come up with a way to reverse lakes filling with silt.