Tahoe Science Consortium Update 2013

August 19, 2013

Dear Presidents Johnson and Wells,

On behalf of the Tahoe Science Consortium, I would like to recognize and thank researchers from the University of Nevada, Reno and DRI for their outstanding contributions to the Tahoe Science Program. Your scientists have worked on many projects over the last eight years to help provide a scientific basis to understand, protect and restore Lake Tahoe and its ecosystems. Scientists from the University and DRI worked in collaboration with researchers from the University of California, Davis, the U.S. Geological Survey, the U.S. Forest Service, Tahoe resource agencies and other organizations around the country to deliver data and expert advice to environmental policy makers, regulators and managers.

The Tahoe research community has advanced our knowledge of mountain aquatic ecosystems and provided the basis for science-based management of Lake Tahoe, a critical and unique national ecological treasure. They have pioneered work to understand nearshore ecology, reduce the impact of aquatic invasive species, model the production and transport of ozone and other pollutants in the Tahoe Basin, improve lake clarity, and restore stream environment zones. They worked diligently to protect special status species, reduce the risk of catastrophic wildfires, understand the impacts of climate change, quantify the impacts of the built environment on Tahoe’s ecosystems, determine the value of ecosystem services, and evaluate the risk of extreme events.

In addition to conducting scientific research, Tahoe scientists have served as subject matter expert advisors to federal and state management agencies and educated the next generation of environmental scientists, engineers, artists and policy makers about the importance of sustainable environmental stewardship. Your researchers have been integral to restoring and protecting Lake Tahoe and sharing this knowledge with similar communities around the world.

Thank you for these outstanding and continuing contributions.


Maureen McCarthy
Executive Director

Air Quality in the Tahoe Basin

10 key questions and answers

Overall, the air in the Lake Tahoe Basin is still much clearer than major urban areas, according to Alan Gertler, vice president of research and chief science officer at the Desert Research Institute. However, because Tahoe is visited by millions of people each year and considered by many as one of the few remaining pristine environments in the West, Gertler knows how critical air quality and visual range are to the future of the basin.

With more than 35 years of air quality research experience at Tahoe and around the world, Gertler shared his expertise to help answer 10 of the most common questions about air quality.

  1. Why should we care about air quality in the Tahoe Basin?
    When we look around Tahoe, the air usually looks clean, but it is one of the few areas in the region where ozone is increasing. It is now at a point where it will likely violate ambient air quality standards. Research also shows that air is a significant source of pollutants that lead to declining water clarity. If we want to reverse this trend, we need to consider making some atmospheric changes.
  2. What air pollutants should we be concerned about?Both nitrogen and phosphorus lead to algae growth in the lake. We should also consider particulate matter because it, too, can deposit in the lake and reduce the clarity of the lake and its surrounding basin. A hazy day is caused by particulate matter. We’re also concerned about ozone because of the negative effects it has on human health and the ecosystem.
  3. What are the sources of the pollutants?Particulate matter comes from road dust or soil, wood burning and emissions from cars, trucks and boats. Nitrogen is also from cars, trucks and boats, while phosphorus is from the soil and wood burning. Ozone is completely formed by chemical reactions in the atmosphere. The sources that are precursors to ozone formation include the mobile sources and the natural emission of hydrocarbon from trees.
  4. air-qualityAre these air pollutants from inside or outside the basin?Studies have shown that a large majority of the pollutants come from sources inside the basin, as opposed to being transported from areas such as the Sacramento Valley or Bay Area. Since the wind tends to blow from west to east, the primary sources are also not from other locales in northern Nevada.
  5. Is wood burning a significant source of the pollutants?Clearly, it is. There are three major sources of wood burning: fireplaces, prescribed burns and wildfires. We’re not necessarily able to control wildfires, but we can control fireplaces and prescribed burns. In the future, we need to consider the weather conditions and air quality prior to scheduling prescribed burns. In winter, greater consideration should be given to controlling the use of fireplaces.
  6. How important is road dust as a pollutant?It’s surprisingly important in terms of contributing to the decline in water quality. Large particles kick up and get scattered in the lake, they reduce visibility, and they contain phosphorus from the soil that leads to the growth of algae in the lake.If we look at the two factors that lead to declining water quality, algae growth and sediment deposition, current estimates show that 55 percent of nitrogen and 15 percent of phosphorus that deposit into the lake come from atmospheric sources.
  7. What can we do to control road dust?Much of the dust comes from the sand and salt used on the roads during the winter snows. From a safety standpoint, we need to use it. However, what we could do instead is to increase the use of street sweepers and liquid de-icers, both of which would reduce soil on the road that can be re-suspended.
  8. What role does fire play in air quality?Fires are important from the standpoint of visibility in the basin. We want to be able to see across the lake, and fires greatly reduce the visual range. It’s important the air be as clear as possible for many reasons, including aesthetics, yet there are no federal standards regarding visibility. The Tahoe Regional Planning Agency, however, does have a visibility standard.
  9. What can we do to control sources of pollutants?The most important sources we have to control are boats and the mobile sources, cars and trucks. Those sources provide the precursors to forming ozone, and they are also a significant source of particulate pollution.
  10. How were the sources of the pollutants determined?Two types of studies were conducted to determine the most important sources of pollutants: a bottom-up approach and a top-down approach. The bottom-up approach involved developing an emissions inventory that counted all activity from traffic, burning and other sources. What we see is that the largest sources of nitrogen are cars, trucks and boats. We also found that major sources of hydrocarbons in the basin are from the mobile sources as well as natural sources such as trees.In the top-down approach, we conducted source-receptor modeling to establish where particulates were coming from. We wanted to determine the significance of road dust and emissions from wood burning and mobile sources.



The Role of Fire in the Tahoe Basin

10 key questions and answers

Lake-Tahoe-UNAE-0016Soil scientists Wally Miller and Dale Johnson, professors emeriti in the College of Agriculture, Biotechnology and Natural Resources at the University of Nevada, Reno, have studied the impact of wildfires in the Tahoe Basin for many years. Their study of the 2002 Gondola wildfire near the Nevada-California border at the south shore of Lake Tahoe has led to new soils management strategies in the basin.

With more than six decades of combined experience and extensive work in forestry, biogeochemical cycling and fire ecology, Miller and Johnson shared their expertise to help answer 10 of the most common questions about the role fire and forest management play in the runoff of nutrients into the upper watershed that feeds into Lake Tahoe, ultimately affecting water quality.

  1. How has the upper watershed been affected by historic fire management strategies?
    Prior to the 20th century, wildfire was a natural part of Sierran ecosystems. It created forests that were less dense, structurally more diverse, had larger trees with less ladder fuels, sparse undergrowth and greatly reduced dead and decaying downed timber. These conditions have been altered by fire suppression over the last 100 years.
  2. What has changed in today’s forest landscape in the upper watershed?
    The buildup of fuels from falling litter and plant life growing beneath the forest canopy has increased the potential for stand-replacing wildfires and resulted in the accumulation of much thicker, nutrient-rich organic residues that can release more available nutrients into runoff and percolating solutions that can reach Lake Tahoe.
  3. What are the potential effects of wildfire on nutrients in the forest floor?
    Wildfire was found to induce an immediate mobilization of inorganic nitrogen and phosphorus, both of which can affect water quality. Although this effect seems to diminish rapidly over time, a wildfire followed by a high water year within the first season after the fire would likely have a much greater impact on water quality than a wildfire followed by a low runoff water year.
  4. What other fire management strategies are available?The most commonly applied alternative to total fire suppression is fuel reduction by either mechanical thinning, prescribed burning or a combination of both.
  5. What are the long-term forest health consequences of controlling post-wildfire brush? Eliminating post-wildfire brush may preclude nitrogen fixation, the natural process by which nitrogen is converted to forms plants can use, and thus not allow replenishment of nitrogen lost during the wildfire. However, leaving brush may preclude the re-establishment of forest vegetation for many decades, creating quite a dilemma.
  6. What are the long-term water quality consequences of controlling post-wildfire brush?
    Thus far, we see no negative water quality effects of the most common nitrogen-fixing species, Ceanothus velutinus, a species of shrub with the common names of snowbrush, redroot and tobacco brush, native to western North America. Water quality effects should be minimal.
  7. What are the long-term forest health consequences of repeated prescribed burning as opposed to mechanical treatment?
    Repeated burning is likely to cause greater nitrogen removal than mechanical thinning, perhaps causing reductions in regenerative growth.
  8. What are the long-term water quality consequences of repeated prescribed burning as opposed to mechanical treatment?
    Repeated burning is likely to cause greater nitrogen removal than mechanical thinning, which may help improve water quality.
  9. What are the effects of combining mechanical thinning and prescribed burning on water quality?
    Prescribed burning in conjunction with mechanical harvest may potentially improve runoff water quality by reducing nitrogen and phosphorus litter mass pools and improving the overall health of forest ecosystems without the danger of a stand-replacing wildfire.
  10. Is climate change important?Absolutely.  The fate of these forest ecosystems in a changing climate will have a direct impact on forest health, fire hazard, biomass mitigation strategies and water quality.

Lake Tahoe to Pyramid Lake: Summer Research Experience in the Arid West

REUResearch combines creativity with a thorough understanding of a subject, as well as the quantitative, analytical and writing skills needed to effectively convey findings to your target audience. In order to build a future generation of talented researchers, it is crucial to give young students an opportunity to partake in the research process so that they may experience the challenges and rewards associated with research. During the past three summers (2010-2012), our National Science Foundation grant, “Lake Tahoe to Pyramid Lake: Summer Research Experience in the Arid West” has supported 27 nationally-recruited undergraduate students to conduct research during an intensive summer research experience for undergraduates or REU program. The overarching goal of our program was to explore the intersections between disciplines in the socioeconomic and natural sciences that inform adaptive watershed management. We also aimed to provide undergraduate students with a comprehensive research experience under the guidance of a faculty mentor in the student’s field of interest.

Over the course of a 10-week program each summer, undergraduate students worked closely with their University of Nevada, Reno, faculty mentor in the following disciplines: fine art, landscape, plant and wildlife ecology, business, hydrology, history, geography, tourism, conservation biology, resource economics, limnology and political science, to develop and implement an array of projects that addressed current issues regarding natural resource management within the watershed. Throughout the summer, students were exposed to local natural resource management issues through a series of lectures and discussions with local managers and scientists designed to highlight the complexity of balancing policy and science to make informed management decisions.

Our program expanded students’ knowledge of a specific topic related to natural resource management in the Lake Tahoe-Truckee River-Pyramid Lake watershed while allowing them to participate in all aspects of the research process.

Our research program culminated in an undergraduate research poster session where students presented the findings of their projects to their peers, faculty and the general public. All projects contributed to an increased scientific and/or socioeconomic understanding of regional conservation issues in an applied context.

Student feedback

Feedback from students was very positive. Of the 27 students that participated in our REU program during 2010-2012, 89 percent indicated this was their first undergraduate research experience. As a learning experience, 52 percent rated the REU program as “fantastic-this is a great way to learn”; the remaining 48 percent indicated they “learned a lot.” Students reported their overall experience with mentors was excellent or good (89 percent), with 88 percent indicating their overall research experience met or exceeded their expectations. When asked if their REU experience changed their perspective on continuing their education, 44 percent of the students indicated they already planned to go to graduate school and still did, while 52 percent reported that our REU program increased their interest in going to graduate school.

By Michael Collopy, 2013 Lake Tahoe Summit Report

Graduate students: An essential component of research programs at Lake Tahoe

Talk to most University of Nevada, Reno (UNR) and Desert Research Institute (DRI) faculty about their research and it does not take long for them to mention how important graduate students are to their programs. They will tell you that their students are extremely bright, hard working, and provide incredibly productive insights to the research projects on which they work. These attributes clearly apply to those students who have conducted their graduate research in the Lake Tahoe Basin. In this report, we have summarized the research contributions of these “Tahoe students,” and provide the reader an overview of their research findings, identify their graduate advisor and degree program, and how their graduate experience benefited them in their career development.

The graduate degree programs through which our “Tahoe students” pass are administered by the University of Nevada, Reno, since, as a research institution, the Desert Research Institute does not administer graduate degree programs. Instead, DRI and UNR faculty work collaboratively to support and mentor graduate students through these UNR-based programs. Most of the graduate degree programs are discipline-specific and are administered by departments; however, four additional programs are interdisciplinary in nature and are administered campus-wide through the UNR Graduate School (i.e., Atmospheric Sciences; Ecology, Evolution and Conservation Biology; Environmental Sciences; and Hydrologic Sciences). Graduate students select and apply to their program of interest. The most qualified students are admitted and then mentored by UNR and DRI faculty through a master’s or doctoral degree program.

All natural resource management is inherently interdisciplinary. In today’s complex world, researchers are increasingly asked to provide objective information that can be used to inform decisions by resource managers. This is particularly true in the complex management environment of Lake Tahoe. UNR and DRI faculty have a long tradition of working collaboratively to meet these needs. During their graduate programs, students also commonly work in these interdisciplinary contexts and develop a variety of skills that will serve them well throughout their careers.

Collectively, our institutions have produced more than 100 graduates who have conducted research on issues important to the Lake Tahoe Basin. We have been able to contact many of these students and have compiled in this report their perspectives on the value of their graduate experience. Several of these graduates now occupy research positions at UNR, DRI, and other academic institutions; others have continued their graduate education at UNR or other universities. The production of high quality graduates is well recognized by federal, regional, state and local organizations, as many former students are now employed by the U.S. Geological Survey, U.S. Forest Service, U.S. Army Corps of Engineers, Tahoe Regional Planning Agency, Nevada Division of State Lands, Nevada Conservation Districts, Truckee Meadows Water Authority, Truckee Meadows Regional Planning, secondary education, and others. Past graduates also are employed by the private sector in areas such as hydrology, hydrogeology, environmental planning, and air quality management. We are very proud of both the individual and collective contributions our students have made to science in the Lake Tahoe Basin.

Many research and management challenges still face the Lake Tahoe Basin and surrounding region, and we believe both the University of Nevada, Reno, and the Desert Research Institute are well positioned to continue the outstanding research and education programs that have been ongoing for several decades. The many departmental and interdisciplinary graduate degree programs through which UNR and DRI mentor students have and continue to produce world class professionals that are making contributions in areas related to air and water quality, runoff and erosion, environmental science, forest health, natural resource management, invasive species, wildlife and biodiversity, environmental planning, and policy. We believe the focus of this year’s Tahoe Summit on climate change and its effects on Lake Tahoe is timely, and that our UNR and DRI faculty and their current and future graduates are well positioned to address this and other emerging issues, and their effects on Lake Tahoe and its surrounding watersheds.

(Editor’s note: Mike Collopy is executive director of the Academy for the Environment at the University of Nevada, Reno; Wally Miller is associate director for research of the Academy for the Environment; Jim Thomas is senior director of the Center for Watersheds and Environmental Sustainability at the Desert Research Institute. Combined, the three have more than 60 years of experience at Lake Tahoe.)