The National Pollutant Discharge Elimination System (NPDES) was originally created as an amendment to the Clean Water Act (CWA) in 1972 and established a permit program to control water pollution by regulating the discharge of pollutants into waters of the United States.  Initially, NPDES permits focused on regulating point source pollution which originates from a definite source, such as industrial facilities, and discharges at a specific point.  In the early 1970s, only one-third of the nation’s waters were considered safe for fishing and swimming.  Through the advancement of CWA and NPDES, two-thirds of the nation’s waters were considered safe by the mid 1990s.

In 1987, an amendment to the CWA directed the NPDES program to address non-point source (NPS) pollution through a phased approach.  NPS pollution does not have a specific origin or discharge location but is considered to be general surface runoff containing pollutants from streets, parking lots, construction sites, homes, businesses and many other sources.

Phase I of the NPDES permit program began in 1990 and applied to construction sites disturbing 5 or more acres of soil and municipalities with populations equal to 100,000 or more.

Phase II of the NPDES permit program became effective on March 10, 2003 and applied to construction sites disturbing between 1 and 5 acres of soil and municipalities with populations between 10,000 and 100,000.  Phase II of the NPDES permit program specifically affects the City of San Luis Obispo region.  For detailed information, please refer to the State Water Resources Quality Control Board (“SWRCB”), San Luis Obispo Region website.

NPDES is a federally mandated program that is implemented and enforced locally.  Currently, all construction sites disturbing 1 or more acres of soil must obtain an NPDES General Permit from the State Water Resources Quality Control Board (“SWRCB”), San Luis Obispo Region.

KEY POINTS:

Construction Site Clean-Up Activity - During any cleaning activity, for example pressure washing or cleaning of tools on a construction site should not result in any water run-off whatsoever.  Simply remember this, the only thing that should go down a storm drain is water from a rain event!

Pressure Washing Activities - Refer to Public Outreach Section for Details.

Project owners are required to submit a complete Notice of Intent (NOI) package to the SWRCB.  A complete NOI package consists of an NOI form, site map and fee.  The General Permit also requires the development and implementation of a Storm Water Pollution Prevention Plan (SWPPP).  The SWPPP should contain a site map which shows the construction site perimeter, existing and proposed buildings, lots, roadways, storm water collection and discharge points, general topography both before and after construction, and drainage patterns across the project.  The SWPPP must list Best Management Practices (BMPs) the discharger will use to protect storm water runoff and the placement of those BMPs.

Agricultural construction related to reservoirs, access avenues and structures are still subject to the General Permit requirement.

The State Water Resources Quality Control Board (“SWRCB”), San Luis Obispo Region website has more information regarding the General Permit and associated requirements.

Even if a construction project is exempt from the General Permit, it is not exempt from discharging polluted runoff under City of San Luis Obispo Municipal Code and the City's SWMP.