Lake Tahoe, the largest and second deepest alpine lake in North America, has experienced a sharp decline in water clarity over the past four decades.
The lake is known for the clarity of its water but since UC Davis’ Tahoe Environmental Research Center (TERC) first started monitoring Lake Tahoe in 1968, the TERC has found evidence that there is a substantial loss in overall water clarity.
“Over those 40 something years, about a third of the clarity of the lake has been lost over that time,” said John Reuter, associate director of TERC. “You used to be able to see down about 100 feet in the late ’60s and early ’70s and now you see 65, 66 feet.”
The California State Water Resources Control Board approved the first phase of a 65-year cleanup plan on April 19, to improve the water quality that has been compromised by non-point sources, such as fertilizer runoff and the transfer of substances to the lake by natural phenomenon.
“Clarity is definitely a big concern but there are other concerns as well,” said Wendy Park, associate attorney for non-profit public interest law firm Earthjustice. “The lake is used as a drinking water source … if you have too much development around the lake and too many pollutants going in, that does affect the people who use the lake for drinking water.”
In addition to the effect on water drinkers, Lake Tahoe’s ecosystem changes with the clarity levels.
“If you don’t have as much light going down to the bottom of the lake, then that affects the species composition,” Park said. “The species living at the bottom of the lake might change because of the different environment that they’re now in.”
Lake Tahoe is located at a higher elevation and is bordered by mountains on all sides, which makes it harder to restore than a lake situated in less rugged terrain.
“When you go to restore any type of ecosystem as big as Tahoe, especially [because] it’s in a very high mountain environment…there’s a big difference between doing restoration projects in more flat land areas than having to do these things on some fairly steep hill slopes,” Reuter said.
“It probably will be expensive and I think that what the plan allows for is a more reasonable time scale, that perhaps this work can be carried within.”
TERC has previously made efforts to restore the lake to its pre-modern clarity levels by improving the current condition, as well as minimizing pollution from its own equipment, while taking samples from the water.
The center owns all of the necessary fuel-efficient sampling equipment and is kept on site at the lake. These boats are used exclusively for taking samples from Lake Tahoe so that no new contaminants can disrupt the ecosystem.
Reuter has been working for the TERC and has seen a lot of changes occur since the late ’60s.
“Things have changed for the better and for the worse,” Reuter said. “There has been more development, more urbanized land use. There’s been a loss of areas that naturally filter out pollutants from water as it drains into the lake. The reduction in the amount of natural filtration and the fact that land is being disturbed … it’s those two things that are really responsible for what we see in the clarity of the lake,” he said.
In addition to the reduction in water quality, the lake’s aesthetic appeal has been influenced by urban development.
“Lake Tahoe is sort of known for its rustic, peaceful setting,” Park said, “but when you have more development, more hotels, and a more urbanized feel, you lose sort of that tranquility.”
DYLAN AARON can be reached at city@theaggie.org.
