The California Water Boards' Annual Performance Report - Fiscal Year 2009-10

PLAN AND ASSESS: SEWAGE SPILLS

GROUP:

SANITARY SEWER OVERFLOWS
(Collection Systems)

MEASURE:

SIZE OF SEWER SYSTEMS
SEWAGE SPILLS

MESSAGE:

Approximately 40% of the collection system accounts for 77% of SSO events in the State.

*KEY STATISTICS FOR FY 2009-10*
Number of Spills	5,180
Volume Spilled (gallons)	24,047,970

MEASUREMENTS

Region	Facilities Regulated Under SSO Program	Facilities With No Spills Reported	Number of Total Sewage Spill Events During FY 09-10	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 15 SSO	Gallons Spilled for Facilities Reporting More than 15 SSO
1	66	38	90	13	14,636	11	151,889	4	17,687
2	123	29	1,725	16	16,407	26	62,257	52	14,494,215
3	104	60	198	18	7,323	17	81,689	14	70,081
4	148	76	429	28	25,650	30	379,394	14	181,160
5F	150	119	151	16	59,977	9	7,075	6	177,484
5R	53	37	47	7	38,880	7	31,353	2	6,042
5S	196	124	2,087	24	83,118	25	3,142,449	23	334,242
6A	22	13	28	6	750	1	25,600	2	3,125
6B	47	33	64	6	9,030	6	87,033	2	28,154
7	34	23	22	7	1,355,600	3	78,160	1	10,664
8	89	46	194	13	32,539	18	38,402	12	422,083
9	49	19	145	8	4,690	16	2,389,230	6	179,902
TOTAL	1,081	617	5,180	162	1,648,600	169	6,474,531	133	15,924,839

Region	Volume of Sewage Spilled	Volume Reaching Surface Water	Percent Reaching Surface Water
1	184,212	154,790	84%
2	14,572,879	14,092,593	97%
3	159,093	51,890	33%
4	586,204	380,730	65%
5F	244,536	132,005	54%
5R	76,275	29,240	38%
5S	3,559,809	3,263,331	92%
6A	29,475	13,600	46%
6B	124,217	83,091	67%
7	1,444,424	1,351,000	94%
8	493,024	405,982	82%
9	2,573,822	938,473	36%
TOTAL	24,047,970	20,896,725	87%

WHAT THE MEASURE IS SHOWING

The data is showing that the number of SSO events are concenetrated in the Regions 2 and 5. These two regions also have some of the larger collection systems in the State. The average spill volume though varies significantly around the State with Region 6 accounting for the largest average spill amount while having the second lowest number of SSO events.

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, 2008 to June 30, 2009. Extracted on June 2009.
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: More information on the Sanitary Sewer Overflow Reduction program is available at: https://www.waterboards.ca.gov/water_issues/programs/sso/index.shtml
The Sanitary Sewer Overflows Incident Map is available at https://www.waterboards.ca.gov/water_issues/programs/sso/sso_map/sso_pub.shtml
The Interactive SSO report: https://ciwqs.waterboards.ca.gov/ciwqs/readOnly/PublicReportSSOServlet?reportAction=criteria&reportId=sso_main

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.

( Updated 9/20/11 )