How many water violations are in Yolo County?

Yolo County has 2,443 total drinking water violations across 90 water systems, of which 1,005 are health-based violations. 92.2% of systems have at least one violation.

How many people get water from Yolo County systems?

Water systems in Yolo County serve approximately 260,218 people through 90 public water systems.

Has PFAS been detected in Yolo County water?

Under EPA UCMR5, 1 of 5 tested systems in Yolo County had at least one PFAS detection (20.0% of the UCMR5-tested subset - not of all 90 SDWIS systems).

What types of water sources supply Yolo County?

Water systems in Yolo County use GW (84 systems), SW (6 systems) as their primary water sources.

Are health-based violations serious?

Health-based violations indicate that drinking water exceeded Maximum Contaminant Levels (MCLs) set by the EPA or failed treatment technique requirements. 41.1% of Yolo County's violations are health-based. Among counties with any SDWIS violations, this extract puts Yolo County in the higher health-based share band. Not all violations indicate immediate health risk, but they require corrective action.

Where does Yolo County sit among U.S. counties for water-system population?

According to EPA SDWIS county population served used on /counties, Yolo County ranks #267 of 3,254 counties by people served, and #28 of 58 counties in California. Ordinals use the same total_population DESC sort as the counties directory. See /methodology#corpus-placement.

Counties → California

Yolo County, California

Compiled by PlainWater · May 15, 2026

SDWIS compliance plate

Sheet CA113 · Yolo County 90 sys · 2,443 viol · #267/3254

VIOL-SEVERE · HEALTH-MID · RANK-TOP · PHOTO-FINISH · PFAS-LOW · SRC-GW · SYS-MID · BOOK-FULL

VIOL-SEVERE 92.2% flagged
HEALTH-MID 41.1% health
RANK-TOP #267/3254
PHOTO-FINISH ±0.2 pp
PFAS-LOW 20.0% detect
SRC-GW GW lead 93%
SYS-MID 90 systems
BOOK-FULL 7/7 fields

Nearest flagged-rate peer: Kern County (+ 0.2 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Yolo County ranks #267 of 3,254 counties by people served, and #28 of 58 counties in California. See methodology · corpus placement.

Yolo County standing, lower-flagged corpus third

Flagged-system rate 92.2% is at or below the corpus lower third (≤ 92.7% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 41.1% is health-based share above the upper third (> 24.5%) . UCMR5 detect rate 20.0% is UCMR5 detect rate in the tested-pool middle third (≤ 33.3%) . Population served ranks #267 of 3,254 · #28 of 58 in California.

Water Systems

System Name	Population	Violations	PFAS
City of Davis	67,457	62	Clean
City of Woodland	61,462	4	Clean
City of West Sacramento	53,355	4	Clean
Uc - Davis	49,616	10	Clean
City of Winters	7,115	8	Detected
Esparto C.s.d.	3,574	13	-
Wild Wings Golf Community	1,115	14	-
Caltrans-Dunigan Rs	1,000	0	-
Pacific Coast Producers	1,000	13	-
Knights Landing Svc. Dist.	944	20	-
Madison Service Dist	876	53	-
Monroe/Leinberger Cntr - Waters	800	14	-
Cal Am - Dunnigan	602	36	-
St Joseph's Church	500	11	-
Clarksburg Middle School	460	24	-
Clark Pacific - Cr 18C	450	26	-
Yolo Co Housing Authority-El Rio Villa	432	14	-
Yolo Fliers Club	415	30	-
Plainfield Elem School - Water	400	8	-
North Davis Meadows	314	31	-
Crew Wine Company	312	12	-
Grace Valley Christian Center	304	0	-
Heringer Estates Winery	300	8	-
Jack in the Box #3465	300	20	-
Sacwest RV Park and Campground	300	17	-
Berryessa Brewing Company	300	11	-
First Baptist Church	300	13	-
Delta High School	250	5	-
Sacramento Yacht Club	250	20	-
Dollar General Store #16171	250	8	-
Unitarian Church of Davis	250	4	-
Jehovah's Witnesses - Kingdom Hall	245	25	-
Cacheville Service Dist	239	77	-
Canyon Creek Resort	212	6	-
Dunnigan Chevron	205	37	-
Americas Best Value Inn	200	20	-
Migrant Head Start Program - Water	200	48	-
United Travel Plaza	200	45	-
The Maples	200	6	-
Jehovah's Witnesses - Southport	200	2	-
Bayer Research and Development LLC	178	13	-
Clarksburg Comm Church	160	9	-
Zamora Shell & Mini Mart	158	59	-
Mariani Nut Company - Buckeye RD	150	10	-
Nelson's Grove	150	6	-
Campers Inn - RV & Golf Course	140	355	-
Road Trip Bar & Grill	120	17	-
Yolo Co Airport	114	13	-
Ihs Nor Cal Youth Trmnt Ctr(sacred Oaks)	104	1	-
Excel Gas and Market	100	72	-

Compare beyond California

Lower-flagged peers for Yolo County

Cross-state counties nearest Yolo County on flagged-system share (92.2%) and cumulative violation count (2,443). In-state neighbours stay on the compliance plate above.

Similar flagged-system rate

Nearest cross-state counties by % of SDWIS systems with at least one violation on record.

4 peers

Similar violation load

Nearest cross-state counties by cumulative SDWIS violation count (all systems in the county).

4 peers

Read our methodology · Check your water system - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater

Compiled by PlainWater, Drinking Water Quality Editorial Process · May 15, 2026

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.