The California Water Boards' Annual Performance Report - Fiscal Year 2016-17

PLAN AND ASSESS: SEWAGE SPILLS

GROUP:

SANITARY SEWER OVERFLOWS
(Collection Systems)

MEASURE:

SIZE OF SEWER SYSTEMS
SEWAGE SPILLS

MESSAGE:

KEY STATISTICS FOR FY 2016-17

MEASUREMENTS - Data last updated on:

Region	Miles of Gravity Sewer (Enrollees Reporting Spills)	Miles of Pressure Sewer (Enrollees Reporting Spills)	Total Size of Collection System (Miles) (Enrollees Reporting Spills)	Facilities With 1 or More Sewage Spill	Number of SSO Events	Volume of SSOs (gallons)	Average SSOs per 100 miles	Average Volume of Spills per 100 miles (gallons)	SSO Events per Facility with Spills

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WHAT THE MEASURE IS SHOWING

WHY THIS MEASURE IS IMPORTANT

TECHNICAL CONSIDERATIONS

Data source: CIWQS. Period July 1, 2016 to June 30, 2017.
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: 10/25/17 )