In 1996, Caltrans requested that the SWRCB consider adopting a single NPDES permit for storm water discharges from all Caltrans properties, facilities, and activities that would cover the Municipal MS4 requirements as well as the statewide Construction and Industrial General Permits requirements. The federal regulations allow for the issuance of system-wide MS4 NPDES permits. The permit was adopted in 1999 and is intended to cover all municipal storm water activities by Caltrans, both in areas that require an MS4 permit and areas that currently do not. It is also intended to cover all Caltrans construction activities that require a permit under the federal regulations.
The Caltrans MS4 Permit did not change in response to Phase II. However, Caltrans projects disturbing an area of one acre or more must submit a Notice of Construction to the Regional Board office before the project begins.