Regional Visibility 90th Percentile ("Worst Visibility Days")
This indicator measures regional visibility on the "worst" days of the year at non-urban areas in the Tahoe Basin. Visibility measures the distance at which an object or light can be clearly discerned by the human eye. Sources of locally generated haze pollutants include entrained/suspended roadway particles, vehicle emissions, residential wood burning, campfires, prescribed fires, and wildfires. Some particles responsible for the degradation of regional visibility in the Tahoe Basin include dust and other pollutants transported into the Basin from areas as far as Asia, and record-setting catastrophic wildfires throughout California and the western states in the last five years. Regional programs such as decreasing the number of polluting wood stoves and work to improve forest health aim to increase regional visibility. Regional visibility is monitored at DL Bliss State Park as part of the national IMPROVE monitoring network.
Status
Regional visibility conditions monitored at the DL Bliss IMPROVE monitoring station.
Evaluation Map
Regional visibility monitoring station at DL Bliss State Park.
2019 Evaluation
- Status
- At or Somewhat Better Than Target
- Trend
- Little or No Change
- Confidence
- High
Applicable Standard
AQ6: Achieve an extinction coefficient of 34 Mm-1 at least 90 percent of the time as calculated from aerosol species concentrations measured at the Bliss State Park monitoring site (visual range of 115 km, 71 miles).
Key Points
- Visibility on the worst visibility days at DL Bliss State Park site has not changed significantly since monitoring began in the early 1990’s.
- Decreases in visibility on the worst days are largely attributed to smoke from severe wildfires.
Delivering and Measuring Success
EIP Indicators
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Non-Compliant Wood Stoves Removed or Retrofitted
This EIP performance measure tracks removal of polluting wood stoves to reduce local air pollution for human and ecosystem health.
Example EIP Projects
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El Dorado County Wood Stove Replacement Program
This project provided incentive rebates for removal of non-conforming wood stoves in El Dorado County.
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Spooner Hazardous Fuel Reduction & Healthy Forest Restoration
This project, completed in 2018, included hazardous fuel reduction and forest ecosystem health treatments on approximately 3,100 acres of the east shore of the Lake Tahoe Basin.
Monitoring Programs
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Regional Visibility Monitoring
Visibility monitoring data are collected, analyzed, and reported by the IMPROVE (national Interagency Monitoring of Protected Environments) network using nationally accepted protocols.