Sewer overflows in California

Name: Sewer overflow events in California
Creator: Sewage Monitor

Sewer overflow record — reported spills, the worst utilities, and how often overflows reached waterways in California.

Reported events

72,702

Total volume

830.0M gal

Reached waterways

10,747(15%)

Latest event

Jun 26, 2026

Worst utilities in California

Ranked by number of reported overflow events.

#	Utility	Events	Volume	Reached water
1	Sacramento Area Sewer District (merged)	18,588	6.9M gal	651
2	Stockton City MUD	2,297	3.1M gal	67
3	Los Angeles City Bureau of Sanitation	2,167	15.4M gal	150
4	Oakland City DPW	2,157	6.3M gal	487
5	Palo Alto City	2,134	164K gal	20
6	San Jose City	1,805	2.2M gal	207
7	Napa Sanitation District	977	1.0M gal	100
8	San Diego City Metropolitan Wastewater Dept (Public Utilities)	905	53.8M gal	191
9	Central Contra Costa Sanitary District	701	795K gal	87
10	Sacramento City	687	296K gal	13
11	Richmond City	588	58.3M gal	302
12	City of Fairfield	587	438K gal	15
13	Antioch City	562	745K gal	10
14	San Mateo City	514	12.6M gal	208
15	Modesto City	505	1.4M gal	26
16	Ross Valley SD	491	4.5M gal	148
17	Roseville City	488	651K gal	13
18	San Rafael Sanitation District	466	340K gal	64
19	Burlingame City PWD	450	3.1M gal	28
20	Mill Valley City	443	86K gal	37
21	San Carlos City	435	197K gal	47
22	Los Angeles Cnty DPW	432	700K gal	258
23	City Of Long Beach	420	275K gal	39
24	Pittsburg City	385	65K gal	8
25	Vallejo Flood & Wastewater District (formerly Vallejo San & Flood Control District)	377	2.2M gal	39
26	City Cleanout	353	21K gal	2
27	1914 Truxtun Avenue	349	813K gal	20
28	Berkeley	341	145K gal	79
29	Single Family Residence	340	4.0M gal	42
30	Whittier City	334	106K gal	104

The largest single reported overflow events.