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Federal water data

County water report

Charles County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for Charles County, Maryland.

Water grade

B

Water score

62.3

State rank

#5

of 24

Health violations

6

EPA SDWIS, 5-year lookback

Watershed impaired

45.5%

66 water bodies assessed

Monitoring sites

55

52,045 recent measurements

Live streamflow

4%

ZEKIAH SWAMP RUN NEAR NEWTOWN, MD

Water at a glance

Key Water Indicators for Charles County

EPA SDWIS

Safety Grade

B

Score: 62.3 / 100

EPA SDWIS

Active Violations

6

5-year health-based lookback

EPA ATTAINS

Watershed Health

46% impaired

66 bodies assessed

USGS NWIS

Streamflow Snapshot

4% of mean

ZEKIAH SWAMP RUN NEAR NEWTOWN, MD

EPA WQP

Monitoring Sites

55

52,045 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

B

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

62.3/100

Health violations

6

Health-based violations

Violations per 100K served

5.0

Population-normalized SDWIS rate

Editorial analysis

Understanding Charles County’s Water

Drinking Water Quality Overview

EPA SDWIS

Charles County earns a B grade for drinking water quality, scoring 62.3 out of 100. Over the past five years, EPA SDWIS records 6 health-based violations — a pattern that public water utilities are required to disclose and correct.

Watershed Conditions

EPA ATTAINS

Under the Clean Water Act §303(d), EPA ATTAINS tracks whether waterways meet quality standards for drinking, recreation, and aquatic life (reporting cycle: 2022). A substantial 45.5% of assessed waterways are impaired (30 of 66 water bodies) across Charles County's watersheds. The leading impairment causes are nitrogen, total and phosphorus, total. Impairment does not mean tap water is unsafe — it measures ambient waterway conditions upstream of treatment, not finished drinking water.

River & Streamflow Status

USGS NWIS

USGS NWIS gauge data (as of 2026-05-14T14:15:00.000-04:00) puts ZEKIAH SWAMP RUN at 4.0 cfs — well below its long-term average at 4% of mean — low-flow conditions worth noting for water-dependent ecosystems. Streamflow is a leading indicator of drought stress, sediment load, and dilution capacity: low flows concentrate pollutants and warm water temperatures, stressing aquatic life and, in surface-water-dependent systems, the source water quality for treatment plants.

Monitoring Network

EPA WQP

EPA's Water Quality Portal (WQP) aggregates monitoring data from federal, state, and tribal agencies. Charles County has extensive coverage with 55 active monitoring sites with 52,045 recent measurements on record. Predominant monitoring categories include physical and nutrient. More monitoring sites generally indicate greater scientific attention to local water conditions — and provide the baseline data that regulators use to set future impairment listings.

Editorial advisory

What the data suggests for Charles County

Water Verdict

Charles County, Maryland receives a fair water quality assessment with a grade of B and a score of 62.3 out of 100. The water supply meets baseline federal standards, but there may be periods of elevated contaminant levels or infrastructure concerns worth monitoring. Separately, EPA ATTAINS assessments cover 66 water bodies in the county's watershed, with 45.5% listed as impaired under the Clean Water Act — a source-water measure that is tracked independently of tap-water compliance. At the most recent USGS reading, local streamflow was below its historical mean at 4.3% — worth watching in drier seasons.

Violation Context

EPA SDWIS records for Charles County, Maryland show 6 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 5.0 violations per 100,000 people served, this rate is moderate and suggests recurring water quality challenges. This compliance record sits alongside an unusually deep monitoring archive: 52,045 water-quality results have been logged across the county in the EPA Water Quality Portal over the past five years.

Consumer Guidance

Tap water in Charles County meets baseline safety standards, though the compliance record shows some violations worth watching. Charles County's drinking-water compliance score is 62.3 out of 100. The violation rate for Charles County is 5.0 per 100,000 people served. Running tap water for 30 seconds before drinking can reduce any localized lead exposure from household plumbing. Requesting your utility's most recent Consumer Confidence Report is the fastest way to identify which specific contaminants were flagged. Nitrogen, Total is the leading impairment cause in Charles County's watershed. With 55 active water-quality monitoring sites in Charles County, data coverage is strong. A pipeline streamflow snapshot from the ZEKIAH SWAMP RUN gauge is also available on this page.

Regional Context

Charles County has better water quality than the average county in Maryland. Its water score is 11.8 points higher than the state average, indicating stronger water system performance relative to neighboring counties.

Advisory text summarizes county-level public records and is not a replacement for your utility's current Consumer Confidence Report or direct local notices.

Contaminants & Resources

Key issues flagged in Charles County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    Nitrogen, Total

    Impairment cause per EPA Clean Water Act §303(d) assessment

  • 2

    Phosphorus (excess nutrients)

    Impairment cause per EPA Clean Water Act §303(d) assessment

  • 3

    Total Suspended Solids (Tss)

    Impairment cause per EPA Clean Water Act §303(d) assessment

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for Charles County

EPA How's My Waterway

Interactive watershed health data for Charles County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Charles County

Consumer Confidence Reports (MD)

Annual water quality reports from utilities in Maryland

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

45.5%

30 of 66 assessed

Moderate concern

Top Impairment Causes

  • 1

    NITROGEN, TOTAL

  • 2

    PHOSPHORUS, TOTAL

  • 3

    TOTAL SUSPENDED SOLIDS (TSS)

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

55

Active in the past 5 years

Measurements Recorded

52K

52,045 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

3.98cfs

May 14, 6:15 PM UTC

vs Long-Term Average

4%

Well below typical

Primary Streamgage

ZEKIAH SWAMP RUN NEAR NEWTOWN, MD

USGS site
01660920
Drainage area
79.9 sq mi
Long-term mean
92.6 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; the percent-of-typical value compares the latest reading against that average.

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Water Cost Estimate

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Annual Total

$558

Monthly

$47

Water Bill

$558/yr

Filter Cost

$0/yr

Safety Grade for Charles County:C — Moderate

Some violations or watershed impairment detected.

Estimates use the national average residential water rate ($0.0068/gal, EPA/AWWA 2023) and EPA WaterSense per-person consumption baseline (75 gal/person/day). Actual bills vary by utility, usage tier, and local infrastructure fees. For informational purposes only.

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Frequently Asked Questions

What is the water quality in Charles County, Maryland?
Charles County, Maryland has a drinking-water quality grade of B with a score of 62.3/100, based on EPA SDWIS compliance data. The county has 6 health-based drinking water violations over the past 5 years. Watershed health, monitoring records, and streamflow snapshots are reported separately on this page.
Are there any water violations in Charles County?
Charles County has 6 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 Charles County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 45.5% of Charles County's 66 assessed water bodies are classified as impaired (30 impaired). The top reported causes are NITROGEN, TOTAL, PHOSPHORUS, TOTAL, TOTAL SUSPENDED SOLIDS (TSS). 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 Charles County?
EPA's Water Quality Portal records 52,045 measurements from 55 monitoring sites in Charles 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 Charles County right now?
Charles County's primary USGS streamgage on the ZEKIAH SWAMP RUN has a pipeline snapshot of 3.98 cubic feet per second — 4% of the long-term mean of 92.61 cfs. This is well below typical — often a signal of drought stress on source water. For the latest gauge feed, visit waterdata.usgs.gov.
How does Charles County water compare to the Maryland average?
Charles County's SDWIS water quality score of 62.3/100 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 Charles County?
Based on EPA SDWIS data, Charles County has a water quality grade of B (62.3/100). This indicates good to excellent water quality with strong SDWIS compliance. 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 Charles County have so many water violations?
Charles County has 6 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 Charles County rank for water quality in Maryland?
Charles County ranks #5 out of 24 counties in Maryland by SDWIS water quality score (1 = best). With a score of 62.3/100, 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

Frederick County

Maryland

C

61.4

Water score

Harford County

Maryland

C

60.8

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 and 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 Evan Brooks, Data EditorUpdated Reviewed by Evan Brooks, Data Editor

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