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Overview
Basics
Basics
Visibility is an important asset to the scenic Lake Tahoe Basin. Since 1990, long-term visibility monitoring has been conducted at D.L. Bliss State Park and South Lake Tahoe to represent regional and sub-regional visibility conditions. The current visibility standards, established by the Tahoe Region Planning Agency, use 1991–1993 monitoring data as the performance standards to be met or exceeded. This project evaluated the current visibility measurements and technologies available for tracking haze in Lake Tahoe and provides recommendations for future monitoring, data analysis, and threshold development.
Completed
2009
2010
2011
$51,624
Alan Heyvaert (alan.heyvaert@dri.edu)
09/20/2017
09/20/2017
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Organizations
EIP Details
EIP Basics
EIP Basics
04.01.01.0049 - P060 Visibility Monitoring and Standards for Lake Tahoe Basin: Assessment of Current and Alternative Approaches
Performance Measures
Expected Performance Measures
Expected Performance Measures
No expected performance measures set for this project.
Reported Performance Measures
Reported Performance Measures
No annual performance measure accomplishments entered for this project.
Funding
Expected Funding
Expected Funding
Reported Expenditures
Reported Expenditures
| Total | 2011 | 2010 | 2009 | |
|---|---|---|---|---|
| Southern Nevada Public Land Management Act (Pacifi... | $51,624 | $17,208 | $17,208 | $17,208 |
| Grand Total | $51,624 | $17,208 | $17,208 | $17,208 |
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Other Details
Watersheds
No watersheds set for this project.
Threshold Categories
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Visibility is an important asset of the Lake Tahoe Basin and has been routinely monitored since 1989. This project will evaluate current visibility measurements and indicators available for tracking haze in the Lake Tahoe Basin and the nearby Desolation Wilderness. The project will provide recommendations for future monitoring, data analysis, and threshold development.
Local and Regional Plans
No Local and Regional Plans set for this project.
Related Projects
Related Projects
No Related Projects set for this project.
External Links
Notes
Notes
| 07/09/2017 6:50 AM | System | Objectives: The goal of the project is to evaluate the current visibility measurements and indicators available for tracking haze in the Lake Tahoe Basin and provide recommendations for future monitoring, data analysis, and threshold development. |
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| 07/09/2017 6:50 AM | System | Findings: Regional and sub-regional visibility, as measured at BLIS1 and SOLA1, have been improving dramatically since 1980’s, but there is a concern about their recent trends. Chemical bext has shown a decreasing trend between 1981 and 2004 with median values dropping 26% at BLIS1 and 32% at SOLA1. The finding is consistent with earlier reports. The change is attributed to lower NH4NO3, OC, EC, and PMcoarse concentrations, probably reflecting the control of motor vehicle, road dust, and residential wood combustion emissions. The 90th percentile bext (or the average of top 20% bext) at BLIS1 appears to increase in recent years (2001–2009). Extremely high bext often resulted from large wildfires, of which frequency and intensity are expected to increase over time owing to climate change. Current Lake Tahoe visibility standards are too low and do not address the national haze rule. The TRPA standards more reflect visibility conditions in 1980-1990. The Clean Air Visibility Rule selected 2000-2004 as the baseline period and requires reasonable progress goals to be established for the most impaired days (worst 20%) and no degradation in visibility to occur for the least impaired days (best 20%). These goals are determined as a uniform rate of visibility improvement from baseline visibility conditions to natural visibility conditions by 2065. To be consistent, the new visibility thresholds (both median and 90th percentile) should be based on bext in 2000-2004. To exclude hazy days caused by wildfires, a non-summer threshold may be developed as most wildfires occur in summer. Also, the 90th percentile threshold may be replaced with an 80th percentile threshold for determining compliance. *** See www.fs.fed.us/PSW/partnerships/tahoescience for additional findings |