PlainWater
Counties → Maryland

St. Mary's County, Maryland

Water Systems
200
Population Served
125,614
Total Violations
2,495
802 health-based
PFAS Detected
2
of 5 tested

Violation Analysis

78.5%
Systems with Violations
12.5
Avg Violations per System
32.1%
Health-Based Violations

Water Source Types

GW
50 systems (25%)

PFAS Contamination

5
Systems Tested
2
PFAS Detected
40.0%
Detection Rate

PFAS (per- and polyfluoroalkyl substances) are persistent chemicals found in drinking water. The EPA has set enforceable limits for several PFAS compounds under UCMR5 monitoring.

Compliance Snapshot

St. Mary's Maryland water systems by violation status, EPA SDWIS records.

No violations on record (8) One or more violations (42)

Violation history is cumulative, many flagged systems have already returned to compliance. Detail pages show per-system context.

Water Systems

System Name Population Violations PFAS
Lexington Park 43,030 31 Clean
Patuxent Naval Air Station (Navfac-Wash) 22,000 164 Clean
Town of Leonardtown 5,000 38 -
Country Lakes 3,016 8 -
Cedar Cove 2,728 5 -
Saint Marys College 2,200 8 -
Chopticon High School 1,845 24 -
Leonardtown High School 1,750 21 -
Wicomico Shores 1,262 18 -
Webster Field Annex, St Inigoes (Navfac) 1,200 37 -
Leonardtown Middle School & Forrest Tech 1,200 22 -
Greenbrier 1,161 5 -
Spring Ridge Middle School 1,075 29 -
Margaret Brent Middle School 1,050 30 -
Breton Bay 1,012 8 -
Lord Calvert Trailer Park 892 45 -
Bradford's Neishyahood Market 818 2 -
Seven Eleven # 21067 Charlotte Hall 805 0 -
Point Lookout State Park North 803 0 -
Hunting Quarters 715 6 -
Rolling Acres 699 5 -
Piney Point 672 9 Clean
Piney Point Elementary School 665 26 -
Lettie Marshall Dent Elementary 650 28 -
St. Clements Shores 620 7 -
Charlotte Hall 615 10 -
Immaculate Conception Roman Cath Chur 614 5 -
Saint Josephs Catholic Church 602 0 -
Benjamin Banneker Elementary School 600 31 -
Hollywood Elementary School 600 25 -
Forrest Farm Subdivision 577 4 -
Laurel Ridge 560 5 -
Persimmon Hills 514 7 -
Wilderness Run 511 9 -
Potomac Speedway 510 3 -
Saint Marys Fairgrounds 502 5 -
Sacred Heart Church 502 0 -
Saint Georges Catholic Church 502 0 -
Oakville Elementary School 475 23 Clean
Patuxent Presbyterian Church 464 0 -
Dynard Elementary School 450 19 -
Hollywood Volunteer Fire Hall 406 7 -
Seven Eleven # 20835 Mechanicsville 403 0 -
Our Lady of the Wayside Church 402 7 -
Saint Francis Xavier Church 402 1 -
Little Flower School 380 58 -
Mechanicsville Elementary 350 22 -
Leonardtown S.h.a./ S.h.a. Maint. 336 1 -
Mount Zion UMC at Laurel Grove 335 7 -
Park Hall Liquors and Deli 330 0 -

Other Counties in Maryland

Montgomery County
56 systems · 1,971,831 served · 1,796 violations
Baltimore city County
13 systems · 1,608,056 served · 122 violations
Anne Arundel County
425 systems · 567,204 served · 5,956 violations
Howard County
88 systems · 309,588 served · 985 violations
Harford County
238 systems · 217,578 served · 3,670 violations
Frederick County
220 systems · 215,362 served · 3,555 violations

Drinking Water Guides

Frequently Asked Questions

How many water violations are in St. Mary's County? ▼
St. Mary's County has 2,495 total drinking water violations across 200 water systems, of which 802 are health-based violations. 78.5% of systems have at least one violation.
How many people get water from St. Mary's County systems? ▼
Water systems in St. Mary's County serve approximately 125,614 people through 200 public water systems.
Has PFAS been detected in St. Mary's County water? ▼
Of 5 water systems tested for PFAS in St. Mary's County, 2 had PFAS detected (40.0% detection rate).
What types of water sources supply St. Mary's County? ▼
Water systems in St. Mary's County use GW (50 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. 32.1% of St. Mary's County's violations are health-based. Not all violations indicate immediate health risk, but they require corrective action.
Data Sources & Methodology

Drinking water violation data from the EPA Safe Drinking Water Information System (SDWIS). PFAS testing data from the UCMR5 monitoring program. SDWIS tracks all public water systems regulated under the Safe Drinking Water Act.

Violations are categorized as health-based (Maximum Contaminant Level exceedances, treatment technique failures) or monitoring/reporting violations. Not all violations indicate an immediate health risk.

Read our methodology - 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 Editorial

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.