waterbycounty
Federal water data

County water report

Anne Arundel County Water Report

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

Water grade

B

Water score

67.5

State rank

#4

of 24

Health violations

11

EPA SDWIS, 5-year lookback

Watershed impaired

48.8%

123 water bodies assessed

Monitoring sites

237

63,231 recent measurements

Live streamflow

86%

PATUXENT RIVER NEAR BOWIE, MD

Water at a glance

Key Water Indicators for Anne Arundel County

EPA SDWIS

Safety Grade

B

Score: 67.5 / 100

EPA SDWIS

Active Violations

11

5-year health-based lookback

EPA ATTAINS

Watershed Health

49% impaired

123 bodies assessed

USGS NWIS

Streamflow Snapshot

86% of mean

PATUXENT RIVER NEAR BOWIE, MD

EPA WQP

Monitoring Sites

237

63,231 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.

67.5/100

Health violations

11

Health-based violations

Violations per 100K served

2.2

Population-normalized SDWIS rate

Data center water stress

Anne Arundel County has 6 facilities in the DCWSI dataset.

ByCounty's DCWSI ranks this county #65 nationally by combining its water score with mapped data center density.

DCWSIThe Data Center Water Stress Index: 60% the county's water-system stress plus 40% how concentrated data centers already are, scored 0-100. Higher means data-center density and water pressure overlap more here.

70.9

0-100 index

Facility count

6

76.0 density percentile

Discharge estimate

Not reported

EPA CWA fields where available

Water vs median

+17.5

Compared with US county median

Named operators

AWSMicrosoft

Mapped facilities

  • AMAZON DATA SERVICES INC LTW060

    JESSUP · Amazon Data Services

    EPA ECHO

  • AMAZON DATA SERVICES INC LTW062

    SEVERN · Amazon Data Services

    EPA ECHO

  • CyberNAP Glen Burnie

    AiNET

    OSM

  • IBM ANNAPOLIS DATA CENTER

    ANNAPOLIS

    EPA ECHO

  • MICROSOFT CORPORATION - YELLOW FACILITY

    ANNAPOLIS JUNCTION · Microsoft

    EPA ECHO

  • TierPoint Baltimore BWI

    Linthicum Heights

    OSM
See the Anne Arundel County data-center reportReview methodology

Data Center Water Budget Calculator

Estimate daily water use for a hypothetical facility in Anne Arundel County.

1 MW1,000 MW
40%100%
799K gallons/dayHigh Impact

Your facility would use 17.2% of this county's industrial water baseline. Verify water rights and long-term drought projections before committing.

17.2% of county industrial baseline3.84 Mgal/day remaining headroom

Based on USGS 2020 water-use data and EPA-standard cooling intensity constants. Not a substitute for site-specific water rights analysis.

Editorial analysis

Understanding Anne Arundel County’s Water

Drinking Water Quality Overview

EPA SDWIS

Anne Arundel County earns a B grade for drinking water quality, scoring 67.5 out of 100. Over the past five years, EPA SDWIS records 11 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 48.8% of assessed waterways are impaired (60 of 123 water bodies) across Anne Arundel County's watersheds. The leading impairment causes are fecal coliform and total suspended solids (tss). 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 2026-05-14T14:45:00.000-04:00) puts PATUXENT RIVER at 335.0 cfs — running somewhat below its historical average at 86% of mean. 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. Anne Arundel County has extensive coverage with 237 active monitoring sites with 63,231 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 Anne Arundel County

Water Verdict

Anne Arundel County, Maryland receives a fair water quality assessment with a grade of B and a score of 67.5 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 123 water bodies in the county's watershed, with 48.8% 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 86.0% — worth watching in drier seasons.

Violation Context

EPA SDWIS records for Anne Arundel County, Maryland show 11 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 2.2 violations per 100,000 people served, this rate is relatively low compared to many U.S. counties. This compliance record sits alongside an unusually deep monitoring archive: 63,231 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 Anne Arundel County meets baseline safety standards, though the compliance record shows some violations worth watching. Anne Arundel County's drinking-water compliance score is 67.5 out of 100. The violation rate for Anne Arundel County is 2.2 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. Fecal Coliform is the leading impairment cause in Anne Arundel County's watershed. With 237 active water-quality monitoring sites in Anne Arundel County, data coverage is strong. A pipeline streamflow snapshot from the PATUXENT RIVER gauge is also available on this page.

Regional Context

Anne Arundel County has better water quality than the average county in Maryland. Its water score is 17 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 Anne Arundel County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    Fecal coliform bacteria

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

  • 2

    Total Suspended Solids (Tss)

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

  • 3

    Phosphorus (excess nutrients)

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

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for Anne Arundel County

EPA How's My Waterway

Interactive watershed health data for Anne Arundel County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Anne Arundel County

Consumer Confidence Reports (MD)

Annual water quality reports from utilities in Maryland

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

48.8%

60 of 123 assessed

Moderate concern

Top Impairment Causes

  • 1

    FECAL COLIFORM

  • 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

237

Active in the past 5 years

Measurements Recorded

63K

63,231 total readings

Most Measured

  • Physical
  • Nutrient
  • Microbiological

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

335cfs

May 14, 6:45 PM UTC

vs Long-Term Average

86%

Below typical

Primary Streamgage

PATUXENT RIVER NEAR BOWIE, MD

USGS site
01594440
Drainage area
348 sq mi
Long-term mean
390 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.

Free tool

Estimate Your Water Costs

Water Cost Estimate

3

3 people  ·  ~225 gal/day

Annual Total

$558

Monthly

$47

Water Bill

$558/yr

Filter Cost

$0/yr

Safety Grade for Anne Arundel 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.

Try the full calculator →

Improve your water quality at home

Berkey filters remove 99.9%+ of contaminants from tap water.

Shop Berkey →

Sponsored

Test your tap water

Tap Score provides professional mail-in water testing.

Get Tested →

Frequently Asked Questions

What is the water quality in Anne Arundel County, Maryland?
Anne Arundel County, Maryland has a drinking-water quality grade of B with a score of 67.5/100, based on EPA SDWIS compliance data. The county has 11 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 Anne Arundel County?
Anne Arundel County has 11 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 Anne Arundel County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 48.8% of Anne Arundel County's 123 assessed water bodies are classified as impaired (60 impaired). The top reported causes are FECAL COLIFORM, 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 Anne Arundel County?
EPA's Water Quality Portal records 63,231 measurements from 237 monitoring sites in Anne Arundel County over the past five years. The most frequently measured characteristic groups are Physical, Nutrient, Microbiological. 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 Anne Arundel County right now?
Anne Arundel County's primary USGS streamgage on the PATUXENT RIVER has a pipeline snapshot of 335 cubic feet per second — 86% of the long-term mean of 389.63 cfs. Flow is within typical range for this gauge. For the latest gauge feed, visit waterdata.usgs.gov.
How does Anne Arundel County water compare to the Maryland average?
Anne Arundel County's SDWIS water quality score of 67.5/100 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 Anne Arundel County?
Based on EPA SDWIS data, Anne Arundel County has a water quality grade of B (67.5/100). 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 Anne Arundel County have so many water violations?
Anne Arundel County has 11 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 Anne Arundel County rank for water quality in Maryland?
Anne Arundel County ranks #4 out of 24 counties in Maryland by SDWIS water quality score (1 = best). With a score of 67.5/100, 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

Howard County

Maryland

A

70.6

Water score

Baltimore city

Maryland

A

71.8

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 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

Explore more data for Anne Arundel County

Property TaxCost of LivingCrime RateIncomeHealthSchoolsDisaster RiskWeatherCounty Score