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The California Water Boards' Annual Performance Report - Fiscal Year 2010-11

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 10-11. .
KEY STATISTICS FOR FY 2010-11

 

MEASUREMENTS  - Data last updated on: 

Region Facilities
Regulated
Under SSO
Program
Facilities
With No
Spills
Reported
Total Sewage
Spill Events
During FY 10-11
Number of
Facilities
Reporting One
Sewage Spill
Gallons Spilled
for Facilities with
1 or less 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 128 facilities reported approximately 62% of the total volume spilled. The data also shows that a large percentage of collection systems regulated (55%) 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, 2010 to June 30, 2011. Extracted on August 9, 2011.
  • 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: 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:  8/31/11 )

 
 

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