USDA Forest Service

Pacific Southwest Research Station


Pacific Southwest Research Station
800 Buchanan Street
Albany, CA 94710-0011

(510) 559-6300

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Realigning the Lake Tahoe Interagency Monitoring Program for use as a monitoring tool

Proposal [pdf]

Lead Researchers:

Robert Coats, Hydroikos Ltd.
Jack Lewis, Consultant
John Reuter, University of California-Davis


Since 1980, public agencies (U.S. Geological Survey [USGS], Tahoe Regional Planning Agency [TRPA], and University of California-Davis [UCD]) in the Tahoe Basin have supported the Lake Tahoe Interagency Monitoring Program (LTIMP), acquiring streamflow and water quality data. The purpose of the LTIMP is to provide data that can be used to monitor water quality conditions and trends. With recent funding cutbacks, changes in regulatory programs, and advent of new technologies, it is time to realign and redesign the LTIMP. The purposes of this project are 1) to plan the realignment and re-focusing of the LTIMP to bring it into line with current needs, budgets constraints and technologies, and 2) to address and correct some historic sources of bias in the data and load calculation methods that jeopardize its usefulness as a long-term monitoring tool. The study team includes four experienced scientists and statisticians presently or previously associated with UC Davis and the USDA Forest Service-Pacific Southwest Research Station. Deliverables will include 1) a statistically-based analysis for alternative sampling programs (e.g., sites, sampling frequency, constituents sampled) along with their associated confidence levels and costs; 2) recommendations for re-focusing and streamlining the LTIMP program using agencies needs and data priorities as a framework; 3) a suite of computer programs for correcting bias and calculating total loads and discharge-weighted mean concentrations, and testing for time trends; 4) a bias-corrected and carefully-vetted historic water quality data base for the LTIMP stations; and 5) monthly progress reports and a written draft report and final report. The report will answer "Key Monitoring Questions" that have been posed by basin agency staff.

Relation to Other Research Including SNPLMA Science Projects

The LTIMP data set is valuable because it is the only tool for monitoring long-term trends in water quality in basin streams. The LTIMP data played a key role in the development of the Lake Tahoe Total Maximum Daily Load (TMDL) program (Lahontan and NDEP, 2010), and have also provided the basis for several peer-reviewed publications on basin water quality (Coats & Goldman, 1993, 2001; Coats et al., 2002, 2008) and basin hydrology (Coats, 2010; Rowe et al., 2002; Jeton, 1999). Over time, however, the development and implementation of new programs in the Tahoe Basin (such as the TMDL and the Tahoe Monitoring and Evaluation program) have significantly changed the regulatory context in which the LTIMP operates. This project will build on previous research on methods of calculating total constituent loads in Tahoe Basin streams (Coats et al., 2002). It will have immediate and direct benefits to monitoring the effects of the TMDL, and the efficacy of agency policies and programs (such as the Lake Tahoe Environmental Improvement Program). It may also be useful in efforts to monitor and model the impacts of fuel management in basin watersheds and it will enhance the usefulness of the LTIMP data base for basic research on water quality in subalpine streams. The computer program will also enable USGS, TRPA and UCD to more effectively provide an annual report on the LTIMP stream monitoring program that evaluates the status and trend of nutrient and sediment loads.

Expected date of final products:

August 2014

Last Modified: Mar 28, 2013 02:52:08 PM