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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Visibility Monitoring and Standards for Lake Tahoe Basin: Assessment of Current and Alternative Approaches

Final Report [pdf]

Lead Researchers:

L.-W. Antony Chen, Xiaoliaong Wang and John G. Watson, Division of Atmospheric Sciences, Desert Research Institute


Visibility is an important asset of the Lake Tahoe Basin and has been routinely monitored since 1989. Despite appreciable improvements recorded in the sub-regional visibility, today the monitoring program is facing challenges including its accuracy, spatial and temporal coverage, and cost. In addition, the current visibility standards to be met or exceeded differ from US Environmental Protection Agency (EPA) guidance for mandatory Class I areas. This project will evaluate current visibility measurements and indicators available for tracking haze in the Lake Tahoe Basin and the nearby Desolation Wilderness, which is a mandatory Class I areas. The project will provide recommendations for future monitoring, data analysis, and threshold development. The project consists of four tasks: 1) Critical review of guidance documents and previous studies; 2) Compilation of relevant visibility and particulate matter databases; 3) Examination of alternative monitoring technologies; and 4) Synthesis, reporting, and recommendations. The project will be completed within 12 months. Alternatives to current measurement methods and indicators may include remote sensing and/or satellite measurements. Findings and recommendations will be communicated to key stakeholders concerned with reducing the effects of airborne particles on visibility and water clarity.

Relation to Other SNPLMA Projects

This project will build upon the recently completed SNPLMA Round 7 science project, "Lake Tahoe source attribution study: receptor modeling study to determine the sources of observed ambient particulate matter in the Lake Tahoe basin," which performed multivariate source apportionment using the LTADS monitoring data. The project will be coordinated with the proposed SNPLMA Round 10 science project, "Lake Tahoe Visibility Impairment Source Apportionment Analysis".

Expected date of final products:

June 2011

Last Modified: Mar 28, 2013 02:52:07 PM