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Storm Water Program

Caltrans Program


Pursuant to the Federal Water Pollution Control Act (Clean Water Act) section 402(p), storm water permits are required for discharges from a municipal separate storm sewer system (MS4) serving a population of 100,000 or more. USEPA defines an MS4 as a conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains) owned or operated by a State (40 CFR 122.26(b)(8)).

The California Department of Transportation (Caltrans) is responsible for the design, construction, management, and maintenance of the State highway system, including freeways, bridges, tunnels, Caltrans’ facilities, and related properties, and is subject to the permitting requirements of Clean Water Act section 402(p). Caltrans’ discharges consist of storm water and non-storm water discharges from State owned rights-of-way.

Before July 1999, discharges from Caltransí MS4 were regulated by individual NPDES permits issued by the Regional Water Boards. On July 15, 1999, the State Water Board issued a statewide permit (Order No. 99-06-DWQ) which regulated all discharges from Caltrans MS4s, maintenance facilities and construction activities. On September 19, 2012, the Department's permit was re-issued (Order No. 2012-0011-DWQ) and will become effective on July 1, 2013.

Caltransí Storm Water Management Plan (SWMP) describes the procedures and practices used to reduce or eliminate the discharge of pollutants to storm drainage systems and receiving waters. A revised SWMP must be submitted to the State Water Board for approval by July 1, 2014.

  • Historical Information
  • bridge

    Caltrans Permit and Forms

    Historical Information

    Frequently Asked Questions

    The Frequently Asked Questions are provided for purposes of guidance to the Department and to interested persons. The provisions of Order No. 2012-0011-DWQ constitute the legal authority with regard to requirements governing the Departmentís actions and the Frequently Asked Questions do not amend those requirements.

    1. Is Caltrans required to comply with the State Water Board statewide Construction General Permit post-construction treatment control requirements for construction projects one acre or greater?

      Caltrans is not required to comply with the post construction treatment control requirements under the Construction General Permit. Section XIII (p. 35) of the Construction General Permit exempts from its post-construction treatment control requirements projects that are located within an area subject to post-construction standards of an active municipal separate storm sewer system (MS4) permit. The 2012 Caltrans Statewide Storm Water Permit (2012 Caltrans Permit) is an active MS4 permit that incorporates post-construction treatment control requirements specific to Caltrans projects statewide. Caltrans projects are therefore exempt from the post-construction requirements of the Construction General Permit and the exemption applies regardless of whether a specific project must comply with the post-construction treatment control requirements of the 2012 Caltrans Permit.

      In Section E.2.d.(p.37), the 2012 Caltrans Permit states that the post-construction requirements shall apply to all new and redevelopment projects that have not completed the project initiation document [PID] phase by July 1, 2013. Therefore all Caltrans projects that have completed or will complete the project initiation phase on or after July 1, 2013 must comply with the post-construction treatment control requirements in the 2012 Caltrans Permit.