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Counties → California

Ventura County, California

SDWIS compliance plate

Sheet CA111 · Ventura County 95 sys · 1,507 viol · #69/3254

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

  • VIOL-SEVERE 87.4% flagged
  • HEALTH-MID 30.7% health
  • RANK-TOP #69/3254
  • PHOTO-FINISH ±0.0 pp
  • PFAS-LOW 15.0% detect
  • SRC-GW GW lead 53%
  • SYS-MID 95 systems
  • BOOK-FULL 7/7 fields

Nearest flagged-rate peer: Tehama County (+ 0 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Ventura County ranks #69 of 3,254 counties by people served, and #12 of 58 counties in California. See methodology · corpus placement.

Ventura County standing, lower-flagged corpus third

Flagged-system rate 87.4% is at or below the corpus lower third (≤ 92.7% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 30.7% is health-based share above the upper third (> 24.5%) . UCMR5 detect rate 15.0% is UCMR5 detect rate in the tested-pool middle third (≤ 33.3%) . Population served ranks #69 of 3,254 · #12 of 58 in California.

Flagged-rate neighbourhood around Ventura County

Lowest/highest poles plus in-state counties nearest Ventura County on % of SDWIS systems with ≥1 violation. Full ladder: /counties.

0% 20% 40% 60% 80% 100% Alpine · lowest Ventura · this county San Francisco · near Sutter · highest 70% 86.7% 87.4% 87.4% 87.5% 88% 97.1%

Source: EPA SDWIS (county aggregates) As of 2026-05-15

Water Systems

System Name Population Violations PFAS
Oxnard Water Dept 200,232 14 Clean
Ventura Water Department 113,500 12 Detected
Ventura Wwd No. 8 - Simi Valley 94,738 12 Clean
Cal American Water Co 66,809 10 Clean
City of Thousand Oaks Water Department 53,157 0 Clean
Camarillo Water Dept 46,824 0 Clean
Golden State Water Company - Simi Valley 45,128 0 Clean
Ventura Cwwd No. 1 - Moorpark 35,514 0 Clean
Camrosa Water District 32,700 7 Detected
City of Santa Paula 31,018 4 Clean
Port Hueneme City Water Dept 21,407 16 Clean
California Water Service Co - Westlake 19,533 0 Clean
Fillmore Water Dept 16,419 13 Clean
Triunfo Water & Sanitation District 13,898 11 Clean
Casitas Municipal Water Dist 11,005 20 Clean
Naval Base Ventura County, Port Hueneme 8,625 14 -
Ojai Water System 6,801 4 Clean
Ventura River Water District 6,100 10 Clean
Naval Base Ventura County, Point Mugu 5,700 14 -
Pleasant Valley Mutual Water Co 5,000 9 Detected
Channel Islands Beach Csd 4,560 0 Clean
Meiners Oaks Cwd 4,200 23 Clean
Smith Forks Water System 3,000 2 -
Rio Mesa High School/Oxnard Uhs 2,600 8 -
Crestview Mutual Water Co 2,079 7 -
Cal American WC - las Posas Estates 2,039 0 -
Cal American Water Company - Piru 2,003 6 -
Ventura Cwwd No. 17 - Bell Canyon 1,946 0 -
Vineyard Avenue Acres MWC 1,820 12 -
Ventura Cwwd No. 38 - Lake Sherwood 1,759 0 -
Cal American WC - Rio Plaza 1,709 11 -
Ventura Cwwd No. 19 - Somis 1,429 2 -
Garden Acres Mutual Water Co 1,335 16 -
Vineyard Ave Estates MWC 1,200 8 -
Limoneira Ranch #1 1,187 6 -
Dempsey Road Mutual Water Co 990 3 -
Rio Manor Mutual Water Co 983 20 -
Nyeland Acres Mutual Water Co 975 53 -
Lake Piru Park - Uwcd 960 28 -
Rio School Dist/Rio del Valle School 820 15 -
Senior Canyon Mutual Water Co 800 42 -
Crown Pointe Estates at Malibu, LLC 690 11 -
Brandeis Bardin Institute 665 14 -
Rancho Sespe Workers Imp Assoc 600 16 -
Glass House Camarillo Cultivation, LLC 600 12 -
Rio School Dist/ Rio Real School 550 12 -
Usfs - Wheeler Gorge Campground 500 50 -
Thomas Aquinas College 472 13 -
Cloverdale Mutual Water Co. 455 8 -
Strickland Mutual Water Company 429 78 -

Compare beyond California

Lower-flagged peers for Ventura County

Cross-state counties nearest Ventura County on flagged-system share (87.4%) and cumulative violation count (1,507). 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

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.