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:

58 percent of regulated facilities did not report a sewage spill in FY 2016-17. Of the spills that did occur, 72 percent of the sewage spilled reached surface waters.

*KEY STATISTICS FOR FY 2016-17*
Facilities reporting no spills:	634
Facilities reporting 6 or more spills:	108

MEASUREMENTS - Data last updated on: 03-26-2018 (9:46 am)

Region	Facilities Regulated Under SSO Program	Facilities With No Spills Reported	Total Sewage Spill Events During FY 16-17	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
1	71	49	69	22	88,530	13	1,356,301	2	47,565
2	131	34	1,085	97	495,487	36	7,628,617	43	7,968,701
3	105	63	174	42	7,621	24	1,466,702	10	737,855
4	144	75	317	69	141,730	28	397,226	13	2,928,509
5F	155	122	90	127	124,314	16	127,967	2	4,944
5R	50	34	39	0	21,925	6	152,055	2	2,866,906
5S	182	104	1,518	0	404,431	27	7,334,675	22	5,835,209
6A	23	15	41	19	150	4	3,233	3	5,340
6B	48	37	28	0	4,645	5	471,202	1	820
7	32	23	19	9	5,850	3	6,295	1	2,419,265
8	90	53	111	37	113,399	13	167,417	5	3,003,150
9	62	25	143	37	175,443	17	534,953	4	1,370,130
TOTAL	1,093	634	3,634	459	1,583,525	192	19,646,643	108	27,188,394

Region	Volume of Sewage Spilled	Volume Reaching Surface Water	Percent Reaching Surface Water
1	1,492,396	1,461,582	98%
2	16,092,805	15,230,105	95%
3	2,212,178	1,388,435	63%
4	3,467,465	2,296,305	66%
5F	257,225	43,358	17%
5R	3,040,886	3,027,208	100%
5S	13,574,315	5,568,873	41%
6A	8,723	4,440	51%
6B	476,667	461,750	97%
7	2,431,410	2,419,000	99%
8	3,283,966	1,878,395	57%
9	2,080,526	1,167,284	56%
TOTAL	48,418,562	34,946,735	72%

WHAT THE MEASURE IS SHOWING

In Fiscal Year (FY) 2016-17, 108 facilities regulated under the SSO Program reported 56 percent of the total volume of sewage spilled statewide. Of the remaining facilities regulated under the SSO Program, 634 of the 1,093 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, 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: 10/24/17 )