California Department of Transportation

Division of Environmental Analysis (DEA) LINKS

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Last Updated: Wednesday, February 7, 2018 10:07 AM


Understanding the technical nature of stormwater will provide Caltrans with a sound scientific basis for controlling, reducing, or treating pollutants in stormwater discharge. The information gathered from these monitoring studies will be used to refine the Caltrans Stormwater Management Program.

The broad scope of these stormwater studies will provide Caltrans with data to develop BMPs for managing stormwater runoff:

  • Statewide Runoff Characterization Studies. Monitoring and analysis of stormwater runoff characteristics from Caltrans highways, maintenance yards, park and rides, rest areas, and construction sites.
  • First Flush Study. Determining changes in stormwater quality throughout storm events.
  • Litter Monitoring and Characterization. Sampling and analysis to determine composition and amounts of litter in highway stormwater runoff.
  • Toxicity Characterization. Testing the toxicity of stormwater runoff to correlate toxicity with chemical constituents.
  • California Toxics Rule (CTR) Characterization. Developing protocols for detecting priority toxic pollutants in stormwater.
  • Particle Size Studies. Determining particle (sediment) size distributions in runoff and the correlation with pollutants.
  • Pathogen Characterization. Determining the types and concentrations of disease-causing organisms from various sources

Alternative treatment methods and devices are being field tested to determine the most practical and effective Best Management Practices (BMPs) for Caltrans facilities:

  • Erosion Control. Evaluating the most suitable methods for stabilizing roadside soil and sediment.
  • Vegetation Management. Monitoring the fate and transport of herbicides (used to control roadside vegetation) in roadway runoff.
  • Structural (Treatment) BMP Pilot Research. Testing a wide range of conventional stormwater treatment devices (structural) at 36 sites.
  • New Stormwater Treatment Studies. Developing new or modifying conventional systems for treating stormwater while promoting efficiency at lower costs.

These research efforts will aid in future watershed planning for reducing stormwater pollution:

  • Storm Drain Outfall Inventory. A statewide inventory of Caltrans storm drain outfalls with their drainage areas.
  • Water Quality Planning Tool. An online tool providing water quality standards and estimated stormwater runoff loads for Caltrans facilities www. stormwater. water-programs. com
  • Beneficial Use Values Database and Related Economic Studies.  Cost-benefit analyses of watershed BMPs from a database of economic values for beneficial water uses.
  • North Coast River Loading Study. Pollutant loadings from Caltrans roadway runoff relative to pollutant contributions from other land uses within a watershed.
  • Small Stream Crossing Study. The effects of stormwater runoff from road crossings on small streams, focusing on two endangered species (coho salmon and steelhead trout).


Division of Environmental Analysis, Stormwater Unit
California Department of Transportation
P.O. Box 942874, MS-27
Sacramento, CA 94274-0001
Email: Division of Environmental Analysis, Stormwater Unit