Storm Water Management

Stormwater Discharge Pollution

Stormwater discharges can carry pollution into our waterways. Also called nonpoint source pollution, this pollution comes from many different sources. Something as simple as rainfall runoff picks up and carries away natural and human-made pollutants, and deposits them into lakes, rivers, wetlands, coastal waters and ground waters. Such nonpoint source pollution can include excess fertilizers, herbicides and insecticides, oil, grease and toxic chemicals from streets and other urban runoff, and sediment from improperly managed construction sites, among others.

In 1989, Congress passed amendments to the Clean Water Act requiring states to address this increasing problem, and California began requiring a National Pollutant Discharge Elimination System (NPDES) permit for stormwater discharges. The NPDES permit program helps address water pollution by regulating point sources that discharge pollutants to waters of the United States.

Water Pollution Prevention Program

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, including Half Moon Bay, shares in general program tasks but must maintain its own stormwater pollution prevention program.

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

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

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

Storm Drain Master Plan

The City's Storm Drain Master Plan (Phase I) establishes an approach to creating a prioritized Capital Improvement Program to mitigate the impacts of stormwater runoff in the City. This document identifies the steps taken to inventory and analyze the existing storm drain system, analyzes capacity restrictions within the storm drain networks of Half Moon Bay, and provides recommendations for Phase II, which will identify the capital improvement projects needed to provide an acceptable level of service throughout Half Moon Bay.

Stormwater Mangement at a Glance

Purpose: Managing stormwater, which may otherwise wash pollutants into Half Moon Bay's waterways, is critical to protecting water quality, wildlife, and public health. Like many San Mateo County municipal agencies, Half Moon Bay is part of the county-wide Municipal Regional Stormwater Permit (MRP) issued by the California Regional Water Quality Control Board in accordance with the Clean Water Act.

Who Must Comply:  New and redevelopment projects that create and/or replace: (1) ≥2,500 SF of impervious surface; or (2) ≥10,000 SF of impervious surface, except for uncovered parking lots, restaurants, auto service facilities, and retail gasoline outlets, which create or replace ≥5,000 SF of impervious surface.