California Water Boards' Annual Performance Report - Fiscal Year  2017-18 

PLAN AND ASSESS: SEWAGE SPILLS

GROUP: 
SANITARY SEWER OVERFLOWS (Collection Systems)
MEASURE: 
SIZE OF SEWER SYSTEMS
SEWAGE SPILLS

 

MESSAGE: 
FY 2017-18: 60.5 percent of regulated facilities did not report a sewage spill in FY 2017-18. Of the spills that did occur, 56 percent of the sewage spilled reached surface waters.
KEY STATISTICS FOR FY  2017-18 
Facilities reporting no spills:665
Facilities reporting 6 or more spills:2,186

 

MEASUREMENTS  - Data last updated on:  09-04-2018 (10:02 am)

Region Facilities
Regulated
Under SSO
Program
Facilities
With No
Spills
Reported
Total Sewage
Spill Events
During FY 17-18
Number of
Facilities
Reporting One
Sewage Spill
Gallons Spilled
for Facilities with
One SSO
Number of
Facilities
Reporting
2 to
5 SSOs
Gallons Spilled
for Facilities
Reporting
2 to 5
SSOs
Number of
Facilities
Reporting
6 or More
SSOs
Gallons Spilled
for Facilities
Reporting
6 or More SSOs
1714266295,66646250,30872,540
2135378329849,346126256,746676676,292
310560129453,729,0607340,7913738,950
41448429760136,6095685,081212389,895
5F15512593112783,9093795,2284110,605
5R50363109,3681930,503653,178
5S1831151,149075,76671186,9951,056278,486
6A231737122,2001414,432224,390
6B4842220113,16010137,33810575
732231892,238149,49000
8905110539149,0194776,3833883,501
963331413016,08355161,58981509,800
TOTAL1,0996652,9204345,072,4245681,344,8842,1862,048,212

 

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Region Volume of Sewage Spilled Volume Reaching Surface Water Percent Reaching Surface Water
1258,514241,97194%
2982,384579,23359%
33,808,8012,910,37176%
4611,585302,25249%
5F889,74268,0978%
5R93,04968,75174%
5S541,247189,94735%
6A21,0222,49012%
6B251,073230,62992%
711,7281,16010%
8308,90371,42623%
9687,472114,61617%
TOTAL8,465,5204,780,94356%
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WHAT THE MEASURE IS SHOWING

In Fiscal Year (FY) 2017-18, 45 facilities regulated under the SSO Program reported 44 percent of the total volume of sewage spilled statewide. Of the remaining facilities regulated under the SSO Program, 665 of the 1,099 collection systems regulated (58 percent) did not report any spills during the FY.

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, 2017 to June 30, 2018 .
  • 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.