State of the Lake Report

SOTL 2014

State of the lake: High (tech) and dry at Tahoe

Lowering a white disk off a boat and into Lake Tahoe’s blue waters was once the most widely used indicator of the lake’s clarity and health. Today, the Secchi disk is still an important tool, but 46 years after the University of California, Davis, first began continuous monitoring of Lake Tahoe, an array of new technologies and computer models are helping scientists better understand what has proven to be a complex ecosystem.

These complexities are examined in “Tahoe: State of the Lake Report 2014,” released today by the Tahoe Environmental Research Center at UC Davis. The report explains how drought, climate change, and other natural and human factors are driving changes at Lake Tahoe.

The report also describes a new real-time network of about 20 monitoring stations -- the first six of which are being installed this month -- to explore what is causing degradation to Lake Tahoe’s nearshore environment. In collaboration with public and private property owners, the Real-time Nearshore Water Quality Network will gather minute-by-minute data about changing water quality conditions. 

“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,” said TERC director Geoff Schladow, who will present the report in a public talk tonight, 5:30 p.m.[this date has passed], at the Tahoe Center for Environmental Sciences in Incline Village. “This really applies to the nearshore, 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 nearshore network will start to fill that void.”   

Climate change: Longer Tahoe summers ahead?

By combining a half-century of data collection at Lake Tahoe with climate-change forecasts, scientists found that summer-like conditions have been extended at Lake Tahoe. 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 F.

Winter temperatures were significantly colder than normal in 2013, while summer was warmer. As a consequence, the peak in the timing of snowmelt was again earlier than historical conditions.  The July surface water temperature was 65.6 degrees F, the warmest in five years.

“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.” 

One likely effect of longer summers is a reduction in dissolved oxygen at the bottom of the lake. Data shows that this could take between five to 10 years if deep lake mixing was totally absent. It would affect fish life and the chemical balance within the lake. Potential solutions include reducing the flux of nutrients to the lake to reduce algal growth.

Lake Tahoe did not mix to its full depth in 2013, the second consecutive year in which this has not happened. The maximum depth of mixing was only 590 feet, reached in March. The lack of mixing was a result of increasing surface temperatures.

The report also includes data related to algae, lake level, stream flows, urban stormwater, the wave environment, and Asian clam control experiments.

The State of the Lake report informs non-scientists about the most important factors affecting lake health and helps influence decisions about ecosystem restoration and management within the Lake Tahoe Basin.

The 2014 State of the Lake was funded by the California Tahoe Conservancy, UC Davis, and the generosity of supporters who value the role of science to save the lake. TERC partners with other research institutions and with resource agencies in the Tahoe Basin to address the current challenges facing Lake Tahoe.

Media contacts:

• Geoffrey Schladow, UC Davis Tahoe Environmental Research Center, (530) 902-2272,

• Zachary Hymanson, UC Davis Tahoe Environmental Research Center, (530) 448-2682,

• Kat Kerlin, UC Davis News and Media Relations, (530) 752-7704,

Tahoe State of the Lake Report 2014

Click here to download a PDF of the entire report (6.5 MB) or visit the Tahoe State of the Lake Report chapters below:

  1. Introduction
  2. Executive Summary
  3. About Lake Tahoe
  4. About the UC Davis Tahoe Environmental Research Center
  5. Map of Tahoe Basin data collection sites
  6. Recent Research Updates
  7. Meteorology
  8. Physical properties
  9. Nutrients and particles
  10. Biology
  11. Clarity
  12. Education and outreach

Historic State of the Lake Reports

Previous State of the Lake Reports are available here.