USDA Forest Service

Pacific Southwest Research Station

Pacific Southwest
Research Station

800 Buchanan Street
Albany, CA 94710-0011
(510) 883-8830
United States Department of Agriculture Forest Service. USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.

Evaluating field and laboratory data for developing surrogate indicators to monitor fine sediment in the Tahoe Basin

Principal Investigators:
Alan Heyvaert, Desert Research Institute
John Reuter, Tahoe Environmental Research Center, University of California, Davis
Masoud Kayhanian, University of California, Davis
Nicole Beck, 2NDNATURE, LLC

Proposal [pdf]

Final Report [pdf]

Project Summary

Fine particle loading is one of the main causes of water clarity loss at Lake Tahoe. Ultimately, tracking and evaluating the effectiveness of Tahoe Total Maximum Daily Load (TMDL) implementation will require continued monitoring of fine sediment particle (FSP) loading to the lake from streams and urban stormwater runoff. Direct measurements of FSP concentrations in terms of FSP mass ([FSP]; mg/liter) and total of number of FSP particles (FSP#; number/liter) can be costly and time consuming. This study compiled the available stormwater and stream FSP data to develop methods for estimating FSP concentrations from surrogate or proxy measurements. A series of multi-parameter linear regression models were systematically tested to identify the most powerful and cost-effective metrics that would predict FSP concentrations and convert between measurement units of mass and number of particles.

The findings and recommendations provided in this study are designed to help guide monitoring, focused data collection, sample analysis, and FSP unit translations to obtain reasonable estimates of FSP concentration in stream and stormwater runoff by Tahoe water quality monitoring programs going forward. Both the Lake Tahoe Interagency Monitoring Program and the Tahoe Regional Stormwater Monitoring Programs will continue to compile relevant data using recommended methods. It is anticipated that updates to these methods, surrogate conversion formulas and turbidity normalization functions will be issued periodically by the associated monitoring programs as additional data accrue.