Climate Resilience Dashboard
EIP Project Tracker
Lake Clarity Tracker
Monitoring Dashboard
Parcel Tracker
Threshold Dashboard
Transportation Tracker
This indicator measures the amount of fine sediment load reduction achieved in the Lake Tahoe Region. Sediment (particularly fine sediment) delivered to Lake Tahoe is known to directly affect the transparency of Lake Tahoe. Excessive amounts of fine sediment are the leading cause of impairment in streams and lakes of the United States. Landscape disturbances including, but not limited to, impervious road and parking lot surfaces, residential and commercial development, wildfire, and the degradation of stream environment zones, can contribute to sediment inputs to the lake and its tributaries. Fine sediment reductions are monitored by partners through the Lake Tahoe Total Maximum Daily Load (TMDL) program.
- Status
- Considerably Better Than Target
- Trend
- Moderate Improvement
- Confidence
- Moderate
- In 2019, TMDL implementors (CalTrans, CLST, Douglas, El Dorado, NDOT, Placer, Washoe) exceeded their load reduction targets and collectively reduced fine sediment particle load by 19.7 percent, preventing roughly 477,000 lbs/yr from reaching the lake (30 percent greater than the target).
- In 2019, approximately 7,500 miles of streets were swept using high-performance sweepers, 29 non-compliant wood stoves were removed or replaced, and nearly seven miles of pedestrian and bicycle routes were constructed. These projects all help to reduce fine sediment particle loads.
- At the September 2020 meeting of the Threshold Update Initiative Stakeholder Working Group, consistent with guidance from the Tahoe Science Advisory Group, the water quality standards related to load reduction were recommended to be removed as threshold standards and retained as Environmental Improvement Program performance measures.
Lake Clarity Tracker Projects
- Runoff from roads and other urban land uses is the single largest source of fine sediment particles (FSP) impacting Lake Tahoe’s clarity, accounting for more than 70% of the FSP load to the lake. TMDL research also found that urban stormwater also provides the greatest opportunity to control FSP pollution. Consequently, restoring Lake Tahoe’s clarity hinges on achieving FSP load reductions in urban stormwater.
- Landscape modification (e.g. impervious cover such as roads or residential and commercial development or logging) influences the volume of runoff, erosion rates, and the ability of the watershed to retain sediment and nutrients. The concentration of sediment and nutrients in stormwater runoff is influenced by the type, magnitude, and location of landscape modifications. Concentration is further mediated by the extent to which practices to mitigate potential impacts are in place. A variety of natural factors also influence the concentration of sediment and nutrients in stormwater concentrations including climate, weather, landscape topography, and vegetation. The Lake Tahoe TMDL estimated that urban upland areas contributed 348 metric tons of fine sediment particles to the lake annually, 72 percent of the annual total (Lahontan and NDEP, 2010a).
EIP Indicators
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Miles of Street Sweeping
Since 2009, EIP partners have swept more than 68,000 miles of roadway in the Tahoe Region collecting fine sediment particles before they reach Lake Tahoe.
Lake Clarity Indicators
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Fine Sediment Load Reduction
TMDL urban implementing partners have acheived greater than total fine sediment particle targets required by permits and agreements.
Monitoring Programs
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Regional Stormwater Monitoring
The Regional Stormwater Monitoring Program measures pollutants in urban runoff to evaluate the effectiveness of pollutant control measures and track and report monitoring findings.
- Status is evaluated relative to the TMDL target for 2019. FSP load reduction in 2019 exceeded the TMDL target by 30%.
- The 2020 TMDL performance management report finds that FSP load reduction has increased from 12.4% of baseline in the 2017 water year to 19.7% of baseline in the 2019 water year. That represents a 59% increase in load reduction between 2017 and 2019.
- Evaluation is based on the Lake Clarity Crediting Program (LCCP).
- Evaluation is based on the Lake Clarity Crediting Program (LCCP).
- Evaluation is based on the Lake Clarity Crediting Program (LCCP).
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