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

PLAN AND ASSESS: SEWAGE SPILLS

GROUP:

SANITARY SEWER OVERFLOWS
(Collection Systems)

MEASURE:

SIZE OF SEWER SYSTEMS
SEWAGE SPILLS

MESSAGE:

Approximately 56% of the regulated collection systems did not report a sewage spill in FY 11-12. 77% of sewage spilled reached surface waters.

KEY STATISTICS FOR FY 2011-12

MEASUREMENTS - Data last updated on:

Region	Facilities Regulated Under SSO Program	Facilities With No Spills Reported	Total Sewage Spill Events During FY 11-12	Number of Facilities Reporting One Sewage Spill	Gallons Spilled for Facilities with One SSO	Number of Facilities Reporting Between 2 and 5 SSO	Gallons Spilled for Facilities Reporting Between 2 and 5 SSO	Number of Facilities Reporting More than 6 SSOs	Gallons Spilled for Facilities Reporting More than 6 SSOs

Region	Volume of Sewage Spilled	Volume Reaching Surface Water	Percent Reaching Surface Water

WHAT THE MEASURE IS SHOWING

The data shows that 116 facilities reported approximately 82% of the total volume spilled. The data also shows that a large percentage of collection systems regulated (56%) did not report any spill during the fiscal year.

WHY THIS MEASURE IS IMPORTANT

SSOs often contain high levels of suspended solids, pathogenic organisms, toxic pollutants, nutrients, oil, and grease. Typical consequences of SSOs include the closure of beaches and other recreational areas, inundated properties, and polluted rivers and streams. This measure tracks the reporting required by the Statewide Sanitary Sewer Order and will help to determine if the sewer system management plans (SSMP), also required by the order, are contributing to a reduction in the number of SSO events.

TECHNICAL CONSIDERATIONS

Data source: CIWQS. Period July 1, 2011 to June 30, 2012. Extracted on August 15, 2012.
Unit of Measure: Average Number of Spills per 100 miles: Measures the number of sewer overflows per 100 miles of sewer lines. Average Volume of Spills per 100 miles: Measures the volume in gallons of sewer overflows per 100 miles of sewer lines.
Data Definitions: Sanitary Sewer: A pipe or conduit (sewer) intended to carry wastewater or water-borne wastes from homes, businesses, and industries to the POTW. Sanitary Sewer Overflows (SSO): Untreated or partially treated sewage overflows from a sanitary sewer collection system.
References: Information on the Sanitary Sewer Overflow Reduction Program
The Sanitary Sewer Overflows Incident Map
The Interactive SSO Report

GLOSSARY

Sanitary Sewer Overflow

A sanitary sewer overflow (SSO) is any overflow, spill, release, discharge or diversion of untreated or partially treated wastewater from a sanitary sewer system. SSOs do not include overflows from blockages or other problems within a privately owned lateral.

Sanitary Sewer Overflow Reduction Program

In May, 2006, the State Water Board adopted a Statewide Sanitary Sewer Order (ORDER NO. 2006-0003-DWQ) to address the issue of SSOs in a consistent and uniform manner statewide. Through the order, California became the first state in the nation to implement a program focused on the regulation of sanitary sewer systems. Sanitary sewer system agencies covered under the order, referred to as Enrollees, are required to report all SSOs for which their agency has responsibility into the State Water Board’s SSO database. Enrollees are also able to report sewage discharges from privately owned laterals or collection systems, for which the Enrollee has knowledge of the event but is not responsible, on a voluntary basis.

( Page last updated: 9/11/12 )