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Storm Drains

In 1989, Congress passed amendments to the Clean Water Act requiring states to address the increasing problem of runoff pollution into storm drains, which carry untreated water directly into nearby waterways.  California began requiring a National Pollutant Discharge Elimination System (NPDES) permit for stormwater discharges, also called non-point source discharges.  To save costs and share information, San Mateo County and all its cities together formed the San Mateo Countywide Water Pollution Prevention Program (SMCWPPP).  Each municipality shares in general program tasks but must maintain its own stormwater pollution prevention program.

Pollution Prevention Program
The San Mateo Countywide Water Pollution Program (SMCWPPP) developed its own stormwater management plan consisting of five major pollution prevention and control sections:

  • Municipal Maintenance Activities
  • Industrial & Illicit Discharge
  • Public Information/Participation
  • New Development & Construction
  • Watershed & Monitoring

Each of the plan’s sections describes goals, existing conditions and tasks that will be accomplished over a five-year permit period.

Municipal Maintenance Activities
Municipal maintenance activities reduce pollutant load into waterways through street sweeping, cleaning catch basins and storm lines, and removing material from drainage channels.

  • Allied Waste Services is contracted to clean 22 miles of city streets.
  • Redwood City Public Works Department is contracted once a year to service 110 catch basins.
  • Report a plugged storm drain or debris-filled catch basin to the City 650.726.7177
  • Collection and recycling of material and waste Allied Waste Services 650.592.2411
  • Hazardous recyclables and waste, contact the San Mateo County 650.363.4718 or

Industrial & Illicit Discharge Controls
Illicit discharges are releases of pollutants or non-stormwater to the storm drain system.  Source control and the Public Works staff respond to calls from the public or incidents discovered in the field.  If the discharging party is present, they are educated about the pollution contribution and are asked to clean up the material they discharged illegally.  Warning notices can be given.  If there is no party on site, the Public Works crew will take appropriate action to contain the discharge.

Public Information/Participation
Public information and participation is one the keys to preventing stormwater pollution.  The general public needs to understand what causes stormwater pollution and the simple things that can be done prevent pollution from entering the storm drain system.  City drain inlets have medallion markers as a reminder.  Brochures are available at City Hall with stormwater information.

New Development & Construction
The new development section of the stormwater program addresses pollution during construction projects, including sediment and erosion control as well as incorporating permanent controls in project designs.  The City of Half Moon Bay Conditions of Approval contains language requiring stormwater pollution prevention practices.  Contractors are informed of the Best Management Practices (BMPs) required on all construction projects.  For more information on new development and construction controls, contact the building department at 650.712.5835.

Watershed & Monitoring
The watershed and monitoring component of the stormwater plan conducts special studies to determine which prevention techniques work best and where to focus pollution prevention efforts.  A watershed is that area of land that would drain rainwater to a particular waterway based on topography.  The amount of imperviousness in a watershed is important because, once it approaches 40 percent, the receiving waterway starts to show significant degradation.  The City drainage master plan is to be updated.