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Lake County, California — public water systems

At a glance

81 active public water systems are filed under Lake County, California in EPA's SDWIS records, together reporting 72,454 people served. The largest is Highlands Mutual Water Company, which reports serving 7,772 people. 43 are community water systems serving people where they live; the other 38 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

81

Population served

72.5K

Community systems

43

Groundwater share

74.1%

How does Lake County compare with other California counties?

Lake County has the 35th-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 72,454 people served in total, the 42nd-largest county figure in the state and 0.2% of the statewide total. The average system here reports serving 895 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 Lake County's drinking water come from?

By primary water source, Lake County's active systems draw on groundwater (58, 72%), surface water (21, 26%), groundwater under influence of surface water (1, 1.2%) and purchased groundwater (1, 1.2%). Overall, 74% rely mainly on groundwater (including purchased groundwater) and 26% 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, Highlands Mutual Water Company, draws primarily on surface water.

What kinds of water systems operate in Lake County?

Lake County's active systems break down as 43 community systems (53%), 2 non-transient non-community systems (2.5%) and 36 transient non-community systems (44%). 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 (74%), local government (21%), federal government (3.7%) and state government (1.2%).

The 50 largest water systems in Lake County

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Active public water systems in Lake County, California
#Water systemCountyPopulation servedTypeSource
1Highlands Mutual Water CompanyLake7,772CommunitySurface water
2Hidden Valley Lake CsdLake6,235CommunityGroundwater
3Konocti County Water DistrictLake5,928CommunitySurface water
4Lakeport, City ofLake4,762CommunitySurface water
5Golden State Water Co.-Clearlake SystemLake4,644CommunitySurface water
6Mt. Konocti Mutual Water CompanyLake4,360CommunitySurface water
7Kelseyville Co Waterworks District 3Lake4,102CommunityGroundwater
8Lake County Csa 21 - North LakeportLake4,046CommunitySurface water
9Cobb Area County Water DistrictLake3,515CommunityGroundwater
10Nice Mutual Water CompanyLake2,929CommunitySurface water
11Clearlake Oaks County Water DistrictLake2,359CommunitySurface water
12Lucerne Water Co. - Cal Water ServiceLake2,129CommunitySurface water
13Lake County Csa 20 - Soda BayLake2,003CommunitySurface water
14Callayomi County Water DistrictLake1,598CommunityGroundwater
15Lake County Csa 2 - Spring ValleyLake1,531CommunitySurface water
16Buckingham Park Water DistrictLake1,521CommunitySurface water
17Lower Lake County Water DistrictLake1,326CommunityGroundwater
18Lakeside County ParkLake1,000Transient non-communityGroundwater
19Upper Lake County Water DistrictLake989CommunityGroundwater
20Rotten RobbieLake899Transient non-communityGroundwater
21Loch Lomond Mutual Water CoLake693CommunityGroundwater
22Harbor View Mutual Water CompanyLake550CommunitySurface water
23Lake County Csa 13 - Kono TayeeLake449CommunityGroundwater
24Harbin Hot SpringsLake401Non-transient non-communityGroundwater under influence of surface water
25Lakeport CinemasLake400Transient non-communityGroundwater
26Anderson Springs CsdLake373CommunityGroundwater
27Huttopia Six Sigma CampgroundLake370Transient non-communityGroundwater
28Cache Creek VineyardsLake310Transient non-communityGroundwater
29Glenhaven Mutual Water CompanyLake300CommunityGroundwater
30Konocti ShoresLake277CommunityGroundwater
31Cal 20 Village and Meadow Pointe ParkLake255CommunityGroundwater
32Clear Water Mutual Water CompanyLake252CommunitySurface water
33Le Trianon ResortLake243Transient non-communityGroundwater
34Mandala Water SystemLake212Transient non-communityGroundwater
35Westgate PetroleumLake210Transient non-communityGroundwater
36Saratoga Springs Retreat CenterLake208Transient non-communityGroundwater
37Walnut Cove Mobile EstatesLake200CommunityGroundwater
38Reel in ResortLake200Transient non-communityGroundwater
39Jitter Bean CoffeeLake160Transient non-communityGroundwater
40Konocti Harbor ResortLake155Transient non-communitySurface water
41Bella Lago Mobile Home ParkLake152CommunityGroundwater
42Pier 1900 Homeowner'S AssociationLake152CommunityGroundwater
43Lake Pillsbury Resort & Marina Inc.Lake150Transient non-communitySurface water
44Corinthian Bay Mutual Water CompanyLake150CommunityGroundwater
45Larsen'S Office ComplexLake112Transient non-communityGroundwater
46Usfs-Sunset Point CampgroundLake110Transient non-communityGroundwater
47Thomas Water SystemLake110Transient non-communityGroundwater
48Lodge at Blue LakesLake100Transient non-communityGroundwater
49Cdf-Konocti Conservation Camp No. 27Lake100CommunityGroundwater
50Blue Lakes Improvement ClubLake90CommunityGroundwater

All other water systems in Lake County (31)

The remaining active systems filed under Lake County, largest first, with the population each reports serving.

Lake County water systems: frequently asked questions

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

EPA's SDWIS records file 81 active public water systems under Lake County, California: 43 community systems (53%), 2 non-transient non-community systems (2.5%) and 36 transient non-community systems (44%).

Who supplies drinking water in Lake County, CA?

The largest community water systems filed under Lake County are Highlands Mutual Water Company (7,772 people served), Hidden Valley Lake Csd (6,235 people served) and Konocti County Water District (5,928 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 Lake County's drinking water come from groundwater or surface water?

Of the 81 active public water systems in Lake County, 74% draw mainly on groundwater and 26% on surface water, counting purchased supplies. The largest system, Highlands Mutual Water Company, uses surface water.

Where can I find a water quality report for Lake 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. 43 community systems are filed under Lake 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 Lake 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 Lake County, California”, https://aquacensus.com/water-systems/california/lake (data as of October 1, 2026).