Reduce Generation and Transport of Nitrate to Achieve Water Quality Standards
This indicator measures whether TRPA has adopted policies to reduce the generation and transport of nitrates and whether there is evidence that nitrate deposition in Lake Tahoe has been reduced. Excessive nitrate discharge into the air and subsequent deposition into the water can negatively impact water quality. Atmospheric sources of biologically available forms of nitrogen have been linked to declines in lake transparency because different forms, such as nitrate and ammonium, provide nutrients for attached and free-floating algae. Nitrogen oxide can come from in-Basin sources such as car exhaust as well as from factory pollution far away. Regional programs such as increased transit and bike trails aim to reduce nitrate deposition into Lake Tahoe. Nitrate deposition is measured at various monitoring stations in Lake Tahoe by UC Davis.
Status
Annual dissolved inorganic nitrogen “DIN” (NO3-N + NH4-N) loading at the mid-lake station.
Evaluation Map
The locations of water quality monitoring stations in Lake Tahoe that are operated by UC Davis.
2019 Evaluation
- Status
- Implemented
Applicable Standard
AQ13: Reduce the transport of nitrates into the Basin and reduce oxides of nitrogen (NOx) produced in the Basin consistent with the water quality thresholds.
Key Points
• Nitrogen emissions from mobile sources in the Basin have declined by more than 66 percent over the last 20 years.
• NOx emissions are likely to continue to decline even further as a result of increasingly strict tailpipe emissions standards and ongoing conversion to electric powered vehicles.
• Atmospheric deposition of nitrogen has not changed significantly in the last 20 years.
Delivering and Measuring Success
EIP Indicators
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Miles of Pedestrian and Bicycle Routes Improved or Constructed
Since 1997 EIP partners have collectively constructed or improved 193 miles of pedestrian and bicycle routes reducing the number of vehicle trips.
Example EIP Projects
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El Dorado Beach to Ski Run Boulevard Bike Trail
This project completed in 2017 provided a critical 0.75 mile missing link trail within the City of South Lake Tahoe's bike trail network.
Monitoring Programs
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Transit
TRPA monitors, evaluates, and updates the Region's multi-modal transportation system for outcomes that decrease dependency on the private automobile, support mobility, and appeal to users.