USGS Activities in the Lake Tahoe Basin

Lake Tahoe is famous for its alpine setting and deep, clear water. Over the last half century, clarity has 

declined by 30–40 feet or 1 foot per year. This decline in clarity has been attributed, in part, to nutrients and 

sediments delivered to the lake by its tributary streams and nutrients from ground-water inflow. 

For decades, the U.S. Geological Survey (USGS) has been involved with a wide range of scientific research 

and monitoring activities in the Lake Tahoe Basin. Water-related activities include stream quantity and 

quality, ground-water levels and quality, and lake levels and quality. Mapping activities include topographic, 

bathymetric, and geologic; land-cover and land-use change delineation; and socioeconomic modeling.

The USGS Water Science Centers in Nevada (NWSC) and California (CWSC), Geology and 

Geography Disciplines, in cooperation with Federal, State and local agencies, are involved with 

the following:

Current Activities

Tahoe Decision Support System: The Tahoe Decision Support System (TDSS) tool is being 

developed to assist the Tahoe Regional Planning Agency (TRPA) with estimating the effects of 

policy decisions on local economic and environmental health. 

http://www.nvwra.org/docs/journal/jnwra_2_article2_halsing.pdf

Land-Cover Characterization: A land-cover characterization study is being completed as part of 

a Nationwide study. The land-cover dataset includes information from LandSat satellites as well 

as many other sources such as census statistics. 

http://geography.wr.usgs.gov/science/tahoe.html

Stream Monitoring: Nutrient, suspended-sediment, water-quality, and streamflow data are currently collected at 20 sites, in cooperation with TRPA and the University of California, Davis, and 

as part of the Lake Tahoe Interagency Monitoring Program (LTIMP). Runoff from the Gondola 

Fire area also is being monitored. These data are used to provide a consistent, long-term database 

and to identify trends throughout the Basin. Data are stored in the National Water Information 

System (NWIS) <http://waterdata.usgs.gov/nv/nwis> and are compiled annually.

http://nevada.usgs.gov/ADR/index.htm

Ground-Water Monitoring: Shallow ground-water in South Lake Tahoe is being studied to determine potential transport of contaminants. 

A ground-water study in the Bijou Creek area of South Lake Tahoe was recently completed as was a ground-water/surface-water interaction study in the Trout Creek area. Data from these studies are stored in NWIS <http://waterdata.usgs.gov/nv/nwis> and are compiled 

annually <http://nevada.usgs.gov/ADR/index.htm>.

Cattlemans Detention Basin Effectiveness: The effects on ground-water quality and levels from the construction and operation of a 

stormwater detention basin along Cold Creek are being examined in partnership with El Dorado County, Calif. This project includes 

examining geochemical processes affecting water quality and using a numerical ground-water flow model to analyze ground-water/

surface-water interactions. http://pubs.water.usgs.gov/sir2004-5254

Tim Rowe, USGS Hydrologist, 

presents results from a USGS 

study at Lake Tahoe. Photograph 

by M.L. Strobel, May 2004.

View of Lake Tahoe looking west-northwest from Gondola Fire burned area; South Lake Tahoe, Calif., and Stateline, Nev., in foreground. 

Photograph by K.K. Allander, October 2002.
Water-Related Studies

Stream Monitoring: Streamflow and lake levels have been collected at 

various sites since 1900. Water-quality has been monitored at various 

times and sites since the 1970’s. http://waterdata.usgs.gov/nwis

Monitoring of Lake Tahoe Basin Lakes: Nutrient and water-quality data 

were collected at five lakes and their outlet streams from 2002 to 2004.

http://pubs.water.usgs.gov/of2004-1333

Organics Survey: Determined the presence of manmade organic compounds in selected tributaries, near their outlets, and at several Lake locations. Semipermeable membrane devices were installed at selected sites 

in 1998 and again in 2002–04.

http://pubs.water.usgs.gov/wrir994218

LTIMP Data Analysis: Nutrient and suspended-sediment loads, yields, and 

trends were calculated from 1988 to 1998 for 20 LTIMP sites. 

http://pubs.water.usgs.gov/wri02-4030

Floodflow: Flood frequencies were studied at 46 stream sites in 1998 

and 2002. http://pubs.water.usgs.gov/fs03-502

Precipitation-Runoff Simulations: Precipitation and associated runoff 

simulations were modeled for 15 subbasins as part of the Truckee-Carson 

Program.

Sediment Source and Channel Erosion: Sources, volume, characteristics, and production rates of sediment and transport of eroded 

material were studied in four basins from 1984 to 1987.

http://pubs.er.usgs.gov/pubs/wri/wri914054

Suspended Sediment and Nutrient Transport: Nutrient and sediment data 

were collected and analyzed from streams in the Edgewood and Glenbrook Creek and Incline Village areas, as well as along several highway 

locations in California, during the 1970’s and 1980’s. 

http://pubs.er.usgs.gov/pubs/wsp/wsp2313

Nutrient and Trace-Metal Chemistry: Nutrients and trace metals were 

researched in the late 1980’s and early 1990’s as part of the USGS 

National Research Program.

Mapping/Digital-Data Products

Urban Dynamics: Remote-sensing techniques were used to analyze landuse change in the South Lake Tahoe area to provide a historical perspective of the change. http://pubs.usgs.gov/of/of01-418/

National Map—Lake Tahoe Pilot Project: Provides public access to highquality geospatial data and information and integrates with TRPA’s Tahoe 

Integrated Information Management System (TIIMS). http://nationalmap.

gov/projects/tahoe.html or http://www.tiims.org

Lake Tahoe Data Clearinghouse: Designed to provide quick and easy 

access to geospatial data and information. http://tahoe.usgs.gov

Tahoe Environmental Geographic Information Systems: Developed 

numerous GIS coverages for TRPA from 1992 to 1995. 

http://pubs.er.usgs.gov/pubs/wri/wri934182

Lake Tahoe Bathymetry: Bathymetry of Lake Tahoe was remapped in 

1997; shallow regions were mapped in 2000. The two data-sets have been 

merged to show the complete bathymetry.

http://walrus.wr.usgs.gov/pacmaps/lt-index.html

Geologic Mapping: A fully attributed spatial database covering most of 

the basin has been completed at a scale of 1:24,000. Large-scale geologic 

information was compiled into a spatial database.

U.S. Department of the Interior

U.S. Geological Survey

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——Timothy G. Rowe, David Halsing, Gary L. Raines, 

Angelia M. Thacker, and Shannon C. Watermolen

For more information about these USGS studies contact:

Tim Rowe, USGS Nevada Water Science Center 

Ph: (775) 887-7627 Email: tgrowe@usgs.gov

Gerald Rockwell, USGS California Water Science Center

Ph: (530) 546-0187 Email: glrock@usgs.gov

David Halsing, USGS Geography, Western Region

Ph: (650) 329-4237 Email: dhalsing@usgs.gov

Gary Lee Raines, USGS Geology, Reno Field Office

Ph: (775) 784-5596 Email: graines@usgs.gov

Additional USGS Websites:

Activities in Nevada: http://nevada.usgs.gov

Geology Discipline: http://geology.usgs.gov

Geography Discipline: http://geography.usgs.gov

California Water Science Center: http://ca.water.usgs.gov

USGS Publications:

National: http://pubs.usgs.gov

Nevada: http://nevada.usgs.gov/biblio/bibsearch.html

California: http://ca.water.usgs.gov/archive/reports/

USGS Fact Sheet 2005-3047

Printed: June 3, 2005