PlainWater
Counties → California

Marin County, California

SDWIS compliance plate

Sheet CA041 · Marin County 49 sys · 805 viol · #248/3254

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

  • VIOL-SEVERE 79.6% flagged
  • HEALTH-HIGH 55.8% health
  • RANK-TOP #248/3254
  • PHOTO-FINISH ±0.2 pp
  • PFAS-CLEAN 0.0% detect
  • SRC-GW GW lead 67%
  • SYS-MID 49 systems
  • BOOK-FULL 7/7 fields

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

According to EPA SDWIS county population served used on /counties, Marin County ranks #248 of 3,254 counties by people served, and #25 of 58 counties in California. See methodology · corpus placement.

Marin County standing, lower-flagged corpus third

Flagged-system rate 79.6% is at or below the corpus lower third (≤ 92.7% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 55.8% is health-based share above the upper third (> 24.5%) . UCMR5 detect rate 0.0% is UCMR5 detect rate at or below the tested-pool lower third (≤ 0.0%) . Population served ranks #248 of 3,254 · #25 of 58 in California.

Flagged-rate neighbourhood around Marin County

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

0% 20% 40% 60% 80% 100% Alpine · lowest Marin · this county Plumas · near Sutter · highest 70% 79.1% 79.6% 79.8% 80% 80.3% 97.1%

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

Water Systems

System Name Population Violations PFAS
Marin Municipal Water District 186,895 1 Clean
North Marin Water District 61,691 6 Clean
Nps Ggnra 18,447 22 Clean
Bolinas Community PUD 2,483 142 Clean
North Marin WD - Pt. Reyes 1,841 3 -
Csp - Angel Island St Park 1,622 0 -
Nps Prns - Beaches 1,560 76 -
Inverness Public Utility Dist 1,445 99 -
Nps Prns - Lighthouse 1,202 7 -
Nps Prns - Glen and Wildcat Campgrounds 1,200 33 -
Lawson S Landing 946 14 -
Stinson Beach County Wtr Dist 583 7 -
Csp - Mt Tam Theatre Well 504 5 -
Csp - Tomales Bay St Park 503 2 -
Tomales High School 427 7 -
Coast Springs - Cal. Water Service (Puc) 388 23 -
Nps Prns - Five Brooks 365 6 -
Muir Beach Community 336 10 -
Nps Prns - Laguna System 316 10 -
Csp - Samuel Taylor St Park 310 3 -
Skywalker Ranch 250 9 -
Tomales Elem & Middle School 225 6 -
Walker Creek Ranch Educational Center 212 21 -
Estero Mutual 206 88 -
Hog Island Oyster Co. 172 0 -
Marin French Cheese Co 143 3 -
Csp - Marconi Conference Center 120 0 -
William Tell House 110 2 -
Nicasio Ranch LLC 104 7 -
Tony S Seafood Restaurant 103 3 -
Camp Tamarancho 101 2 -
Nick's Cove 90 4 -
Tomales Tin Building 82 6 -
Green Gulch Farm 75 6 -
Csp - Mt Tam East Peak System 75 0 -
Nps Prns - Sky Camp Campground 75 0 -
McEvoy Ranch Water System 66 0 -
Audubon Canyon Ranch - Mgp Picher 50 27 -
Audubon Canyon Ranch - Mgp Volunteer 50 27 -
Marshall Boat Works 50 0 -
Tomales Church of the Assumption 50 0 -
Maif - Marshall Aqua Improvement Forum 50 0 -
Nicasio School 48 56 -
Slide Ranch 47 14 -
Nicasio Valley Ranch Mutual 36 31 -
Blue Mountain Center 35 9 -
Shoreline School Dist: Bus Garage 26 2 -
Diekmann's General Store 25 0 -
Devils Gulch Ranch Water System 25 6 -

Compare beyond California

Lower-flagged peers for Marin County

Cross-state counties nearest Marin County on flagged-system share (79.6%) and cumulative violation count (805). 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.