Suspended Sediment Load (Surface Runoff)
Suspended Sediment Load (Surface Runoff) is include in the Threshold Dashboard. Threshold Indicators are evaluated against Threshold Standards every 4 years. Thresholds are environmental goals and standards for the Lake Tahoe Basin that indirectly define the capacity of the Region to accommodate additional land development.
Status
Fine Sediment Particle load measured at outfalls around the Tahoe Basin. Total for “consistent sites” refers to sites that were monitored in both 2014 and 2015. Sites that have no data for 2014 were only installed for water year 2015. Source: Tahoe Resource Conservation District
Evaluation Map
A map shows all stormwater monitoring locations during water years 2014 and 2015. Source: Tahoe Resource Conservation District
2015 Evaluation
- Status
- Insufficient Data to Determine Status or No Target Established
- Trend
- Insufficient Data to Determine Trend
- Confidence
- Low
Applicable Standard
Reduce total annual nutrient and suspended sediment loads as necessary to achieve loading thresholds for tributaries and littoral and pelagic Lake Tahoe.
Key Points
No Key Points
About the Threshold
- This indicator measures the total suspended sediment load (measured as fine sediment particle load) delivered to Lake Tahoe via direct surface runoff. Fine suspended sediment (fine sediment particles) are the primary driver of the decline in lake clarity (responsible for 55 to 60 percent of the decline) and urban upland areas are the dominate source of fine sediment particle in the basin (Lahontan and NDEP, 2010a). The TMDL estimated that 72 percent of the fine sediment particle load originates from urban sources. The TMDL estimated that a 71 percent reduction (from 2004 loading estimate) in fine sediment particle load from urban upland sources over 65 years would be required to achieve the pelagic clarity standard.
- 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. Sediment and nutrient load in stormwater runoff is influenced by the type, magnitude, and location of landscape modifications and the extent to which practices to mitigate potential impacts are in place. A variety of natural factors also influence the load of sediment and nutrients in stormwater including climate, weather, landscape topography, and vegetation. The TMDL estimated that 72 percent of total fine sediment particle load basin wide originates from urban upland sources.
Delivering and Measuring Success
Transportation Indicators
- Acres of Environmentally Sensitive Land Acquired
- Acres of Forest Fuels Reduction Treatment
- Acres of SEZ Restored or Enhanced
- Disturbed Areas Restored, Enhanced, or Created
- Educational and Interpretive Programs Produced
- Fine Sediment Load Reduction
- Forest Roads Created
- Forest Roads Inspected and Maintained
- Impervious Coverage Retired
- Miles of Roads Decommissioned or Retrofitted
- Miles of Street Sweeping
- Nitrogen Load Reduction
- Non-Compliant Wood Stoves Removed or Retrofitted
- Parcels Inspected for Defensible Space
- Parcels with Stormwater BMPs
- People Served
- Phosphorous Load Reduction
Rationale Details
- Insufficient data to determine status. Data reported in this assessment is load as measured at specific catchments and no overall estimate of load was available at this time. Load reduction estimates and condition assessment commitments are documented in the credit accounting platform of the TMDL. A more robust picture of load in stormwater will be available in March 2017 after credit declaration and associated verification associated with the first TMDL milestone is complete. Fine sediment particle load at all monitoring location outfalls was 3,004 kilograms for water year 2014 and 6,894 kilograms for water year 2015. The two years are not comparable because three additional sites were added in 2015 and total surface volume was much greater in 2014.
- Insufficient data to determine trend. Stormwater monitoring under the IMP component of RSWMP began in 2014. The IMP of RSWMP is currently funded through 2019 by SNPLMA, and trend assessments are expected to be included in future evaluations.
Confidence Details
- – Low. Where insufficient data exists to determine status, confidence in the status determination is low. There is moderate confidence in the data because it is collected using widely recognized, standardized national protocols (see monitoring approach) with quality assurance/quality control procedures. Only a small proportion of outflows are sampled and not all runoff events are sampled. Regional estimates of overall load and load reduction are not available at this time.
- Low. No trend assessment was performed because both the nature and limited duration of the data preclude trend assessment.
- Low.
Additional Figures and Resources
No photos available.
No documents available.