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EPA SDWIS

Frederick County Water Quality

Frederick County, Maryland

Water Grade

C

Water Score

61.4

Violations

10

State Rank

#7

of 24 (1 = best)

EPA SDWIS Compliance

Drinking Water Quality

Water Quality Grade

C

Based on EPA compliance history and violation data

Water Score

61.4/100

Higher = better quality

Health Violations

10

Health-based violations

Violation Rate

5.5%

Systems with violations

Water Advisory: Frederick County

Water Verdict

Frederick County receives a fair water quality assessment with a grade of C and a score of 61.4 out of 100. The water supply meets baseline federal standards, but there may be periods of elevated contaminant levels or infrastructure concerns worth monitoring.

Violation Context

Frederick County has recorded 10 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 5.5 violations per 1,000 residents, this rate is moderate and suggests recurring water quality challenges.

Consumer Guidance

Tap water in Frederick County meets baseline standards, but residents who are immunocompromised or have young children may want to use an NSF-certified water filter as a precaution. With 10 recorded health violations, staying informed about utility communications and boil-water notices is especially important. For long-term peace of mind, request your utility's latest Consumer Confidence Report and consider independent water testing if you have specific health concerns.

Regional Context

Frederick County has better water quality than the average county in Maryland. Its water score is 10.9 points higher than the state average, indicating stronger water system performance relative to neighboring counties.

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

41.7%

35 of 84 assessed

Moderate concern

Top Impairment Causes

  • 1

    TEMPERATURE

  • 2

    TOTAL SUSPENDED SOLIDS (TSS)

  • 3

    PHOSPHORUS, TOTAL

Source: EPA ATTAINS · Reporting cycle 2022

Impairment is determined under the Clean Water Act §303(d): a water body is impaired when it fails to meet state-defined quality standards for designated uses (drinking, recreation, aquatic life). Assessment coverage varies by state — counties without assessed water bodies are not shown.

Past 5 years

Water Quality Monitoring

Monitoring Sites

38

Active in the past 5 years

Measurements Recorded

23K

23,059 total readings

Most Measured

  • Physical
  • Nutrient
  • Organics, Other

Categories measured most frequently

Data from the EPA Water Quality Portal (WQP), aggregating monitoring records from federal, state, and tribal sources. Each measurement represents a single sample analyzed for a specific characteristic (e.g., E. coli, pH, dissolved oxygen, nitrogen).

Live USGS Streamgage

River & Stream Conditions

Current Discharge

2,660cfs

May 14, 6:55 PM UTC

vs Long-Term Average

28%

Well below typical

Primary Streamgage

POTOMAC RIVER AT POINT OF ROCKS, MD

USGS site
01638500
Drainage area
9,651 sq mi
Long-term mean
9,540 cfs

One representative streamgage (the one with the largest drainage area in the county). Many counties have multiple gauges — this view summarizes the primary one. The long-term mean is the full-record annual average; "% of typical" compares the latest reading against that average.

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Frequently Asked Questions

What is the water quality in Frederick County, Maryland?
Frederick County, Maryland has a drinking-water quality grade of C with a score of 61.4/100, based on EPA SDWIS compliance data. The county has 10 health-based drinking water violations over the past 5 years. Watershed health, monitoring records, and live streamflow are reported separately on this page.
Are there any water violations in Frederick County?
Frederick County has 10 health-based drinking water violations recorded by the EPA over the past 5 years. Health-based violations indicate instances where contaminant levels exceeded EPA Maximum Contaminant Levels (MCLs). Violations may have been resolved — check with your local water utility for current status.
How healthy are the watersheds in Frederick County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 41.7% of Frederick County's 84 assessed water bodies are classified as impaired (35 impaired). The top reported causes are TEMPERATURE, TOTAL SUSPENDED SOLIDS (TSS), PHOSPHORUS, TOTAL. Impairment means the water body fails to meet state quality standards for at least one designated use — drinking water source, recreation, aquatic life, or fish consumption. Note: watershed impairment doesn't always translate to tap-water issues; treatment plants can remove most regulated contaminants.
How much water-quality monitoring happens in Frederick County?
EPA's Water Quality Portal records 23,059 measurements from 38 monitoring sites in Frederick County over the past five years. The most frequently measured characteristic groups are Physical, Nutrient, Organics, Other. Each measurement is a single sample analyzed for one characteristic (E. coli, pH, dissolved oxygen, etc.). High monitoring density means more scientific evidence behind any reported signal — it does not by itself indicate water quality.
What's happening with rivers in Frederick County right now?
Frederick County's primary USGS streamgage on the POTOMAC RIVER is currently reading 2,660 cubic feet per second — 28% of the long-term mean of 9,540.37 cfs. This is well below typical — often a signal of drought stress on source water. For genuine real-time data, visit waterdata.usgs.gov.
How does Frederick County water compare to the Maryland average?
Frederick County's SDWIS water quality score of 61.4/100 is higher than the Maryland state average of 50.5. The average water quality grade across Maryland is D, based on data from 24 counties with available SDWIS data.
Is tap water safe to drink in Frederick County?
Based on EPA SDWIS data, Frederick County has a water quality grade of C (61.4/100). This indicates moderate compliance. Some violations have been recorded but overall standards are maintained. The grade speaks to the public water system, not the watershed — for watershed-level concerns, see the Watershed Health zone. For the most up-to-date information, contact your local water utility or review your Consumer Confidence Report (CCR).
Why does Frederick County have so many water violations?
Frederick County has 10 health-based drinking water violations on record from the EPA SDWIS database. A higher violation count can result from aging infrastructure, underfunded water utilities, agricultural runoff contamination, or industrial pollution. Counties with more water systems may also see more violations simply due to scale. Residents concerned about water quality should consider independent water testing and home filtration systems.
How does Frederick County rank for water quality in Maryland?
Frederick County ranks #7 out of 24 counties in Maryland by SDWIS water quality score (1 = best). With a score of 61.4/100, it falls in the top third of counties statewide. The ranking reflects EPA SDWIS compliance only — not watershed impairment, monitoring density, or streamflow, which are tracked separately on this page.

Counties with Similar Water Quality

Washington County

Maryland

C

61.5

Water score

Harford County

Maryland

C

60.8

Water score

Charles County

Maryland

B

62.3

Water score

Data Sources

Drinking-water compliance data from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. Scores reflect compliance history and health-based violation counts.

Watershed health and impaired-waterway data from the EPA ATTAINS Clean Water Act §303(d) assessments — state-reported, EPA-finalized.

Water-quality monitoring counts from the EPA Water Quality Portal (WQP) — federated USGS, EPA, and state agency sampling records over a rolling 5-year window.

Live streamflow from the USGS National Water Information System (NWIS) — continuous discharge measurements from the largest-drainage gauge in each county, compared against the full-record long-term annual mean.

Disclaimer: This data is informational only. It is not health, legal, or professional advice. For concerns about your specific water supply, contact your local water utility.

By Logan Johnson, Founder & Data EditorUpdated Reviewed by Logan Johnson, Founder & Data Editor

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