Requirements for Erosion and Sediment Control

Soil erosion and sedimentation pose a serious threat to water quality.

  • Erosion is the wearing away of the ground surface as a result of the movement of wind or water.
  • Sedimentation is the accumulation of soil and other matter transported from the land by wind or water.

The State Water Resources Control Board mandates the regulation of runoff and the treatment of stormwater into drainage systems and waterways under the National Pollutant Discharge Elimination System (NPDES) permit, including construction stormwater from project sites.

The prevention of stormwater pollution is a responsibility shared by everyone involved in the development/construction process, including Project engineers, developers, contractors, property owners, municipal planners, and municipal building inspectors.

The San Mateo County Planning and Building Department requires the following types of projects to submit an erosion and sediment control plan for review and approval prior to the issuance of any building permit:

  • Any site with land disturbance of 1 acre or more.
  • All sites where the scope of development or land alteration requires a Grading Permit.
  • New or Major (50% valuation or greater) Building Projects where development, construction, or land alteration will occur on a slope greater than or equal to 20% and/or within 100 feet of a creek, wetland, or coastline.
  • New pool construction.
  • Demolition projects involving removal of a building pad during or just before the wet season, where the demolition and construction permits are not issued concurrently.
  • Any project involving work within a waterway.
  • Construction sites within the Fitzgerald Marine Reserve ASBS watershed (map included as Attachment A) that involve soil disturbance and are subject to a building or grading permit.
  • Projects with demolition, grading or construction happening during or just prior to the wet season (subject to actual weather conditions, but typically October 1 through April 30).

Projects that involve 1 acre or more of land disturbance are also required to demonstrate coverage under the State’s Industrial General Permit (Order 2014-0057-DWQ), prior to issuance of a grading permit.