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Last Updated: Wednesday, February 7, 2018 10:25 AM


since 1997, Caltrans has monitored strom water at more than 188 sites statewide, yielding more than 200,000 data pointsStormwater and dry weather runoff could carry unwanted pollutants into our waterways via storm drain inlets. As the steward of thousands of storm drains throughout the state's freeways, park and rides, maintenance stations, and other facilities, Caltrans is actively pursuing scientific information on stormwater.

When Caltrans began stormwater monitoring in 1997, differences in collecting and reporting data from sites across the state showed the need for data consistency.

Caltrans has created a system to manage and use the stormwater data. The system includes protocols for monitoring activities, standardizing and checking the data, data reporting, and a database for storage and access.

Data Management Process

  1. Stormwater samples collected from monitoring stations Field personnel collect runoff samples from automated monitoring equipment using sampling protocols from the Caltrans Guidance Manual: Stormwater Monitoring Protocols (available online).
  2. Samples processed in labs
    Water samples collected from runoff are analyzed in the lab. Various indicators of water quality tested include conventional parameters, metals, nutrients, organic material, bacteria, and toxicity.
  3. Data prepared and validated with Laboratory EDD Processing Tool An electronic data deliverable (EDD) report is prepared using software developed by Caltrans that checks for errors. An independent party validates the data using automated software to ensure that monitoring protocol standards are met.
  4. Data report standardized with the Data Reporting Protocols Validated lab data are combined with data records for each monitoring sample, rainfall event, and site characteristic. The data are then formatted into a standardized report for the Caltrans database.
  5. Data input and stored in the Caltrans database
    Data records for water quality, and information on the monitoring site and storm event sampling are stored in the Caltrans database (MS Access ®) for later analysis.
  6. Statistical Analysis of Data Performed An Excel ® add-on program applies a unique Data Analysis Tool (DAT) to calculate summary statistics for analytical data with non-detects. This DAT is used by stormwater researchers to report the data in a consistent manner.
  7. Caltrans uses stormwater data to plan and implement its Stormwater Management Program, as part of the NPDES permit requirements.

Key Tools for Managing the Data

One of the highlights of the data management system is the user-friendly query interface which allows easy retrieval of data from the databaseThe data management tools were created by teams of engineers and scientists - people who have applied state-of-the-art technology to increase our current understanding of the nature of stormwater pollution. These key tools are:

  • Caltrans Guidance Manual: Stormwater Monitoring Protocols
  • Laboratory EDD Processing Tool: Error Checker and Automated Data Validation
  • Data Reporting Protocols
  • Caltrans Database created with MS Access®
  • Data Analysis Tool
  • Hydrologic Tool



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