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Colusa County, California — public water systems

At a glance

29 active public water systems are filed under Colusa County, California in EPA's SDWIS records, together reporting 35,121 people served. The largest is Caltrans-Maxwell Reststops, which reports serving 15,000 people. 9 are community water systems serving people where they live; the other 20 are non-community systems, such as schools, workplaces, campgrounds and gas stations with their own supply.

Dataset updated . Source: EPA SDWIS/ECHO, refreshed quarterly.

Active systems

29

Population served

35.1K

Community systems

9

Groundwater share

96.6%

How does Colusa County compare with other California counties?

Colusa County has the 55th-most active public water systems among the 201 counties listed for active California systems in EPA records; among the 72 with 3 or more systems, the median has 73. Its systems report 35,121 people served in total, the 51st-largest county figure in the state and less than 0.1% of the statewide total. The average system here reports serving 1,211 people, well below the California average of 5,706. Population figures are what each system reports; people served by more than one system, such as a wholesaler and the town that buys from it, are counted by each.

Where does Colusa County's drinking water come from?

By primary water source, Colusa County's active systems draw on groundwater (28, 97%) and surface water (1, 3.4%). Overall, 97% rely mainly on groundwater (including purchased groundwater) and 3.4% on surface water, compared with 85% and 15% across California. Groundwater means the system draws its water from wells or springs fed by underground aquifers. The county's largest system, Caltrans-Maxwell Reststops, draws primarily on groundwater.

What kinds of water systems operate in Colusa County?

Colusa County's active systems break down as 9 community systems (31%), 5 non-transient non-community systems (17%) and 15 transient non-community systems (52%). A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. A non-transient non-community water system regularly serves at least 25 of the same people for more than six months a year, but not where they live. Schools, factories, office buildings and hospitals with their own supply are typical examples. A transient non-community water system serves places where people do not stay long, such as gas stations and campgrounds, and regularly serves at least 25 people a day for at least 60 days a year. EPA lists their owner types as private (66%), local government (24%), federal government (6.9%) and state government (3.4%).

Water systems in Colusa County

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Active public water systems in Colusa County, California
#Water systemCountyPopulation servedTypeSource
1Caltrans-Maxwell ReststopsColusa15,000Transient non-communityGroundwater
2City of ColusaColusa6,447CommunityGroundwater
3City of WilliamsColusa5,538CommunityGroundwater
4Arbuckle Public Utility DistrictColusa2,778CommunityGroundwater
5Maxwell Public Utility DistrictColusa1,175CommunityGroundwater
6Colusa Industrial PropertiesColusa533Non-transient non-communityGroundwater
7Menf-Fouts Springs CgColusa531Transient non-communityGroundwater
8Colusa Co. Wwd #1 - GrimesColusa512CommunityGroundwater
9Morning Star Pkg. Co.-Wms.Colusa390Non-transient non-communityGroundwater
10Colusa Co. Wwd #2 - PrincetonColusa382CommunityGroundwater
11Colusa Co. Service Area #2-StonyfordColusa250CommunityGroundwater
12Colusa Co. Service Area #1-Century RanchColusa246CommunitySurface water
13Del Oro Wc - Arbuckle DistrictColusa185CommunityGroundwater
14Colusa LandingColusa168Transient non-communityGroundwater
15Sun Valley Rice CompanyColusa151Non-transient non-communityGroundwater
16Arbuckle Golf ClubColusa126Transient non-communityGroundwater
17Menf-Letts Lake CgColusa118Transient non-communityGroundwater
18Wilbur Hot SpringsColusa97Transient non-communityGroundwater
19Adam'S Vegetable OilsColusa95Non-transient non-communityGroundwater
20Adm Rice Inc..Colusa87Non-transient non-communityGroundwater
21Highway 20 Trailer ParkColusa63Transient non-communityGroundwater
22Grimes Boat LandingColusa50Transient non-communityGroundwater
23Richmond Hunting Club-MaxwellColusa40Transient non-communityGroundwater
24Willow Creek M.W.C.-LambertvilleColusa31Transient non-communityGroundwater
25Kingdom Hall of Jehovah'S Witness-WmsColusa26Transient non-communityGroundwater
26Terhel Farms Trailer Park 02Colusa26Transient non-communityGroundwater
27Terhel Farms Trailer Park 01Colusa26Transient non-communityGroundwater
28T&P FarmsColusa25Transient non-communityGroundwater
29Ward'S Boat LandingColusa25Transient non-communityGroundwater

Colusa County water systems: frequently asked questions

How many public water systems are in Colusa County, California?

EPA's SDWIS records file 29 active public water systems under Colusa County, California: 9 community systems (31%), 5 non-transient non-community systems (17%) and 15 transient non-community systems (52%).

Who supplies drinking water in Colusa County, CA?

The largest community water systems filed under Colusa County are City of Colusa (6,447 people served), City of Williams (5,538 people served) and Arbuckle Public Utility District (2,778 people served). Which system serves a particular address depends on its service area, which EPA's SDWIS records do not include; a water bill or the local utility can confirm it.

Does Colusa County's drinking water come from groundwater or surface water?

Of the 29 active public water systems in Colusa County, 97% draw mainly on groundwater and 3.4% on surface water, counting purchased supplies. The largest system, Caltrans-Maxwell Reststops, uses groundwater.

Where can I find a water quality report for Colusa County?

Each community water system must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1, covering the previous calendar year. 9 community systems are filed under Colusa County, so the report to look for is the one from the system that supplies your address.

How can I check violations for a water system in Colusa County?

Open the system's profile from the list on this page. Each profile shows the most recent Safe Drinking Water Act violations in EPA's records, with plain-English labels and whether each one is resolved. For current compliance status, EPA ECHO is the primary source.

More California water systems

About this data

Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.

Cite as: AquaCensus, “Public water systems in Colusa County, California”, https://aquacensus.com/water-systems/california/colusa (data as of October 1, 2026).