The Science of Sustainability

Lake Tahoe: Can We Save It?

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Lake Tahoe’s famously blue waters – which make it the clearest lake of its size in the United States – attract three million visitors to California and Nevada each year. But decades of development, and now climate change, threaten this national treasure. This QUEST half-hour documentary takes you behind the scenes with the scientists working to keep the lake pristine and protect it for generations to come.

But Lake Tahoe isn’t the only body of water that comes to mind when we think about America’s most treasured lakes. The Great Lakes, an interconnected set of five lakes which include lakes Erie, Superior, Huron, Michigan and Ontario, hold 18% of the water on the face of the Earth. Both Lake Tahoe and the Great Lakes face environmental challenges, but are differently equipped to handle them because of their particular characteristics.

Similarities between Lake Tahoe and the Great Lakes

    • Potable Water Sources
Tahoe dam

Lake Tahoe delivers millions of gallons of water every day for residents and farmers along the Truckee River. The Tahoe dam was built in 1909. Photo: Arwen Curry / QUEST Northern California.

Both the Great Lakes and Lake Tahoe provide potable water to surrounding populations, though at very different scales. The Great Lakes deliver 43 billion gallons per day, hundreds of times more than Lake Tahoe. Lake Michigan alone provides drinking water to 12 million residents. Around three quarters of the water taken from the Great Lakes is used to cool down power plants.

 

      • Climate Change Impacts
Visitors at Lake Tahoe's Sand Harbor.

Warmer temperatures are nice for visitors, like these at Lake Tahoe's Sand Harbor, in Nevada. But they could lead the lake to move away from its famous indigo blue and more towards green. Photo: Arwen Curry / QUEST Northern California.

Lake Tahoe and the Great Lakes are warming up, just like all lakes around the world. “We’ve had some summers where the surface temperature is very, very warm, compared to 20, 25 years ago,” said Brant Allen, of the University of California-Davis’ Tahoe Environmental Research Center. Although it’s nice for visitors, heat encourages the growth of microscopic algae that scatter the light off the lake’s surface and make it appear cloudy.

Up north, intense spring rains that washed fertilizer into Lake Erie, coupled with a warm summer, contributed to a 2011 algae bloom that covered the surface of the lake’s western basin with a bright green scum. “All of the factors that happened in 2011 are the types of factors that we expect to see more commonly in the future,” said Anna Michalak, a Great Lakes researcher at Stanford University.

        • Invasive Species
Quagga mussels attached to pipes in Lake Mead

Quagga mussels clog pipes, like these in Nevada's Lake Mead. Authorities are working hard to keep the mussels out of Lake Tahoe. Photo: National Park Service.

Zebra mussels and quagga mussels have invaded the Great Lakes, damaging sport fisheries and clogging intake pipes with their hard shells, to the tune of $1 billion per year. The mussels have hitched rides out west on recreational boats. But so far they haven’t reached Lake Tahoe, and authorities there are fighting hard to keep them out by inspecting every boat before it goes into the water.

“At first, I thought the public would be very resistant to the idea of paying fees for boat inspections,” said Geoff Schladow, director of the University of California-Davis’ Tahoe Environmental Research Center. “But the more people I talk to, they’re very accepting of the need for it.” Lake Tahoe is already dealing with the invasive Asian clam, which produces algae mats that wash up on its beaches, and an aquatic plant called milfoil, which sticks to boats’ propellers.

Differences between Lake Tahoe and the Great Lakes

            • Depth v. Width
Eagle Falls over Emerald Bay

The water pouring into Lake Tahoe doesn't carry many of the nutrients that algae feed on. This is one of the reasons why the lake is so clear. Eagle Falls flows into Emerald Bay, one of Lake Tahoe's most iconic spots on the California side of the lake. Photo: Gabriela Quirós / QUEST Northern California.

Lake Tahoe is the eleventh deepest lake in the world. Lake Erie is the tenth largest lake in the world. At its deepest point, Lake Tahoe plunges to 1,645 feet – which makes it deeper than the Empire State building is tall. And this depth helps the lake stay clear, since its 39 trillion gallons of water are able to dilute the tiny dirt particles and nitrogen and phosphorus that threaten its transparency. By contrast, Lake Erie’s deepest point is only about 200 feet deep. With less water to dilute the nutrients that algae feed off, Lake Erie is particularly vulnerable to algae blooms.

                  • Watershed Size

Lake Tahoe is fortunate in that its watershed is small and the soil around it is relatively nutrient-poor. The 63 rivers that feed Lake Tahoe travel through an area about the size of the lake itself. Most lakes have watersheds many times bigger, which give tributaries more of a chance to pick up pollutants as they flow towards the lake.

Lake Erie has suffered from a steady flow of phosphorus from agriculture, which has contributed to bad algae blooms. Corn is planted widely in the Plains – partly to produce ethanol for use as a biofuel – and requires a lot of fertilizer. “The national biofuels program is what’s pushing more corn production,” said Stanford scientist Anna Michalak.

Homeowners around Lake Tahoe are required to keep dirt from flowing into the lake.

Homeowners around Lake Tahoe are required to keep dirt from flowing into the lake. Brad Kohler watches as workers install a channel and sediment trap at the bottom of his driveway in Tahoe City, California. When it rains, this mechanism will trap dirt particles. Photo: Arwen Curry / QUEST Northern California.

To keep their watersheds from becoming sources of pollutants, authorities at Lake Tahoe and the Great Lakes have efforts underway to prevent dirt from running into nearby rivers (Tahoe), and reduce the amount of fertilizer used on crops (Great Lakes).

Additional Links

University of California-Davis Tahoe Environmental Research Center (TERC)

Tahoe Boat Inspections

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Category: Biology, Climate, Environment, Television, Video, Water

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Gabriela Quirós

About the Author ()

Gabriela Quirós is a TV Producer for KQED Science & Environment. She started her journalism career in 1993 as a newspaper reporter in Costa Rica, where she grew up. She won two national reporting awards there for series on C-sections and organic agriculture, and developed a life-long interest in health reporting. She moved to the Bay Area in 1996 to study documentary filmmaking at the University of California-Berkeley, where she received master’s degrees in journalism and Latin American studies. She joined KQED as a TV producer when QUEST started in 2006 and has covered everything from Alzheimer’s to bee die-offs to dark energy. She has shared two regional Emmys, and four of her stories have been nominated for the award as well. Independent from her work on QUEST, she produced and directed the hour-long documentary Beautiful Sin for PBS, about the surprising story of how Costa Rica became the only country in the world to outlaw in-vitro fertilization.
  • Mark Mintmire

    Good article. Good industry practice or reducing "highly managed" and treated areas of the course while also restoring some of the native grasses to add character to the course. Look at http://www.reecoursegolf.com for an all-natural product that will help you reduce chemical fertilizer use and help improve water efficiency.

  • Andrew

    Great article! I hope Stanford University golf course managers will read this article and change their ways on their expansive and water thirsty golf course. They divert water from a dam that blocks threatened steelhead migration to water their course. If they implemented the above measures, they could remove the sediment filled dam, restore steelhead runs that run through the golf course, improve water quality, and provide needed flood retention basins that would improve the course and provide wetland habitat. Some university's are quicker to adapt than others…. great work NC State University!

  • Ted Swift

    Nice summary of some of the issues facing Lake Tahoe! A few questions left hanging, but overall, really well done.

    • reddman

      I use to live there In the 90's what I remember most was how restrictive it was for homeowners,of course that means dollars,so it will be a place only for the wealthy and the very poor that work at the casinos and other low paying jobs.

  • billybo

    I was convinced up to the end. Then the UC Davis TERC professor (who makes his living off studies of Lake Tahoe) mentions that Lake Tahoe is a place to expirement to see what works and doesn't work in order to benefit hundreds of thousands of lakes around the country. The current Tahoe TMDL regulations burden the local residents, who are ultimately paying to provide a large regulatory experiment to benefit other lakes around the country, as noted by the professor. They don't know for sure if forcing the local people to abide by these expensive regulations will solve the problem, but they are willing to force them to pay for it so they can visit from other places. This seems to place the financial burden on local residents, be they rich or poor.

  • Len

    Thank you, I appreciate the story…. but did you say in the intro that "reservoirs" are threatened by pollution and development? That makes no sense…. reservoirs are development, requiring a dam, and degrade water quality, which threatens rivers and native wildlife. Thanks again.