DRI researchers are studying various aspects of air, water, and soil throughout the Lake Tahoe Basin. To estimate groundwater recharge from perennial stream channels, Todd Mihevc studies one of the many streams that feed into Lake Tahoe.

Reno area residents know that the Sierra Nevada range they see each day makes for more than just great skiing and a beautiful backdrop. They know, for instance, that the snow clinging to those mountaintops feeds the rivers, streams, lakes, reservoirs, and underground springs that make their valley habitable. It's a similar story throughout the west, where mountain watersheds support development, recreation, and vital ecosystems. What residents may not know, is that many mountain watersheds are poorly understood and may be in danger of being compromised by both natural and human forces. That's why the Center for Watershed Environmental Sustainability (WES) was chosen as one of DRI's two new interdisciplinary science programs.

Researchers from WES are busy investigating the complexities of the Lake Tahoe Basin in California and Nevada. According to Dr. Roger Jacobson, interim director of the center, WES was a logical step for DRI. "It was really an area where we hadn't maximized our potential," Jacobson comments. "For instance, while we had quite a few researchers doing work on mountain watersheds, we had very little presence at Tahoe, the area's most vital watershed. We had the people, the interest, and the equipment, but we needed a push to get things going there."

That push came from the Institute's new organizational structure, and DRI researchers have enthusiastically expanded their work at Tahoe. "We're all extremely excited about the work at Lake Tahoe," says Jacobson. "There are probably more research opportunities than in any other western mountain lake, and the research at Tahoe is proving to be truly interdisciplinary. We have 34 people from throughout the Institute working in WES, with good representation from all three divisions. There is also close collaboration with scientists and engineers from the University of Nevada, Reno (UNR)."

Institute scientists have many research capabilities suited to studying the Tahoe area, including snow and glacier hydrology.

To this end, DRI researchers are studying various aspects of air, water, and soil throughout the Lake Tahoe Basin. For instance, there are several important air quality issues at Tahoe, not the least of which is the discovery that dirty air means a dirty lake. "We think that about half the nutrients in the lake are deposited from the air," explains Jacobson. "The key question is whether that air pollution comes from within the basin or is being carried from outside, possibly from the Sacramento area." Controlled burns in the surrounding forest lands are also a potential pollution source, and DRI researchers are looking at how they contribute to overall nutrient levels.

In addition, DRI researchers are examining how erosion along beaches and shorelines adds sediments and nutrients to the lake as well as the effects of restoration efforts. Eroding slopes and stream banks are often rebuilt for greater stability. There are many ways to do this, and Institute scientists are working to determine which of these efforts is simultaneously cost-effective and limits large amounts of sediment from reaching the lake.

Another major issue at Lake Tahoe is water clarity. DRI hopes that, by using new methods and instrumentation, the Institute can help create a more comprehensive and accurate understanding of the lake's clarity. "A lot of money is being spent to maintain clarity, and we feel those big-dollar decisions should be based on the best information," notes Jacobson.

Researchers currently rely on a surprisingly low-tech method for judging clarity. A light-colored disc is lowered into the water, and the depth at which it disappears from view is recorded. While that simple approach can be effective, Jacobson points out that it measures clarity at only a few specific locations and only in the upper layers of the water. "We'd like to take a more high-tech approach. By using optical and laser methods we will be able to create a sort of three-dimensional map of the lake's clarity."

Yet another water-related issue is being investigated in conjunction with UNR, the University of California, Davis and the U.S. Geological Survey. Three experimental watersheds are being established in the basin at Ward Creek, Incline Village, and South Lake Tahoe. These sites will be carefully studied and monitored to give researchers a better understanding of watershed processes and the various factors that impact them. "For instance, there will be some stream restoration going on at the Incline watershed," explains Jacobson. "This will be a chance to look at the 'before, during, and after' of restoration and see exactly how it affects the condition of the streams and lake."

In Jacobson's assessment, Lake Tahoe is probably the most closely studied and well-managed mountain watershed in the west. "Tahoe is a decade ahead in this regard and had plans in place to protect the lake as far back as the 1960s." This progressive attitude toward management and protection is an important attraction to researchers, since what they discover can be quickly put into positive action. "That's very exciting to a researcher," says Jacobson. "Much more so than your work being published and put on a shelf."

Ultimately, Jacobson sees Lake Tahoe and WES as a perfect pairing. "The projects apply many disciplines to real environmental issues, and the findings have an excellent chance of being applied. We can really help the decision-makers translate science into management." It's also an excellent opportunity for DRI researchers to learn as much as possible about mountain watersheds in general. "We are hoping that we will become well entrenched there and gain a clear understanding of the processes at work in the basin. We'll then be in an excellent position to export that knowledge to other western mountain watershed areas that may not be as carefully managed as Tahoe. There are lots of opportunities out there." Opportunities are what DRI's new structure is all about: opportunities to understand environmental problems, opportunities to solve those problems, and opportunities to make a difference.

Jackie Allen

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