The California Water Boards' Annual Performance Report - Fiscal Year 2011-12

MEASUREMENTS  - Data Last Updated on: 

WHAT THE MEASURE IS SHOWING

Although there is significant variation between the Regional Water Boards, the distribution of municipalities enrolled in either Phase I or II is consistent with size of municipalities in each region. For example, the most populated areas have also the larger number of medium and large facilities enrolled in Phase I. Not all Regions are enrolling small municipalities under the statewide general permit.

WHY THIS MEASURE IS IMPORTANT

The MS4 permits require the discharger to develop and implement a Storm Water Management Plan/Program with the goal of reducing the discharge of pollutants to the maximum extent practicable (MEP). MEP is the performance standard specified in Section 402(p) of the Clean Water Act. The management programs specify what best management practices (BMPs) will be used to address certain program areas. The program areas include public education and outreach; illicit discharge detection and elimination; construction and post-construction; and good housekeeping for municipal operations. In general, medium and large municipalities are required to conduct chemical monitoring, though small municipalities are not.

TECHNICAL CONSIDERATIONS

• Data Source: CIWQS. Period July 1, 2011 to June 30, 2012. Extracted on July 30, 2012.
• Unit of Measure: Number of active MS4 Facilities during FY 11-12.
• Data Definitions: Permits Active as of June 30, 2012.
• References: Information on the Water Boards’ NPDES Stormwater program
  Public Reports and Data
  Enforcement and Compliance Assurance Information

GLOSSARY

Municipal Stormwater Phase I Facilities

The Municipal Storm Water Permits regulate storm water discharges from municipal separate storm sewer systems (MS4s). Under Phase I, which began in 1990, the Regional Water Boards have issued NPDES MS4 permits to permittees serving populations greater than 100,000 people. Many of these permits are issued to a group of co-permittees encompassing an entire metropolitan area. These permits are reissued as the permits expire.

Municipal Stormwater Phase II Facilities

Under Phase II, the State Water Board adopted a General Permit for the Discharge of Storm Water from Small MS4s (WQ Order No. 2003-0005-DWQ) to provide permit coverage for smaller municipalities (10,000 to 100,000 people), including non-traditional small MS4s which are governmental facilities such as military bases, public campuses, prisons and hospital complexes.

 

( Page last updated:  9/10/12 )