The California Water Boards' Annual Performance Report - Fiscal Year 2014-15

PLAN AND ASSESS: SEWAGE SPILLS

GROUP:

SANITARY SEWER OVERFLOWS
(Collection Systems)

MEASURE:

SIZE OF SEWER SYSTEMS
SEWAGE SPILLS

MESSAGE:

Approximately 44 percent of the collection systems regulated under the SSO program reported one or more sewage spill during FY 2014-15.

*KEY STATISTICS FOR FY 2014-15*
Number of SSO Events:	4,580
Volume of Sewage Spills (gallons):	11,327,150

MEASUREMENTS - Data last updated on: 10-17-2015 (2:54 pm)

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
1	1,945	137	2,082	27	71	214,936	3.41	10,324	2.63
2	15,789	424	16,213	98	1,173	6,217,807	7.23	38,351	11.97
3	4,109	252	4,361	45	201	466,013	4.61	10,686	4.47
4	20,784	226	21,010	77	448	858,378	2.13	4,086	5.82
5	21,624	1,063	22,687	121	2,248	1,434,647	9.91	6,324	18.58
6	3,770	150	3,920	26	85	331,683	2.17	8,461	3.27
7	2,797	213	3,010	10	22	226,150	0.73	7,513	2.20
8	13,979	522	14,501	43	142	883,282	0.98	6,091	3.30
9	10,407	443	10,850	34	190	694,254	1.75	6,399	5.59
TOTAL	95,204	3,430	98,634	481	4,580	11,327,150	4.64	11,484	9.52

WHAT THE MEASURE IS SHOWING

The data show that in Fiscal Year (FY) 2014-15 sanitary sewer overflows (SSO) events were concentrated in the San Francisco Bay (Region 2) and Central Valley (Region 5) regions. The two regions have some of the largest collection systems in the State; combined the two regions account for almost 40 percent of the State's total size (in miles) of collection systems. Additionally, the two regions accounted for 68 percent of all sewage spilled in the State during the FY. The number of spills and the average spill volume varied significantly throughout the State; Region 2 reported the largest average spill volume (with 38,351 gallons spilled per 100 miles), while the Colorado River Basin Region (Region 7) reported the fewest number of spill 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, 2014 to June 30, 2015.
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: 9/21/15 )