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County water report

Washington County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for Washington County, Wisconsin.

Water grade

B

Water score

63.2

State rank

#8

of 71

Health violations

4

EPA SDWIS, 5-year lookback

Watershed impaired

10.8%

268 water bodies assessed

Monitoring sites

108

282,771 recent measurements

Live streamflow

No gauge

Primary USGS station not mapped

Water at a glance

Key Water Indicators for Washington County

EPA SDWIS

Safety Grade

B

Score: 63.2 / 100

EPA SDWIS

Active Violations

4

5-year health-based lookback

EPA ATTAINS

Watershed Health

11% impaired

268 bodies assessed

USGS NWIS

Streamflow Snapshot

No gauge

Primary USGS gauge not mapped

EPA WQP

Monitoring Sites

108

282,771 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.

63.2/100

Health violations

4

Health-based violations

Violations per 100K served

4.6

Population-normalized SDWIS rate

Editorial analysis

Understanding Washington County’s Water

Drinking Water Quality Overview

EPA SDWIS

Washington County earns a B grade for drinking water quality, scoring 63.2 out of 100. Over the past five years, EPA SDWIS records 4 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 notable 10.8% of assessed waterways carry an impairment designation (29 of 268 water bodies) across Washington County's watersheds. The leading impairment causes are phosphorus, total 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.

Monitoring Network

EPA WQP

EPA's Water Quality Portal (WQP) aggregates monitoring data from federal, state, and tribal agencies. Washington County has extensive coverage with 108 active monitoring sites with 282,771 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 Washington County

Water Verdict

Washington County, Wisconsin receives a fair water quality assessment with a grade of B and a score of 63.2 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 268 water bodies in the county's watershed, with 10.8% listed as impaired under the Clean Water Act — a source-water measure that is tracked independently of tap-water compliance.

Violation Context

EPA SDWIS records for Washington County, Wisconsin show 4 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 4.6 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: 282,771 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 Washington County meets baseline safety standards, though the compliance record shows some violations worth watching. Washington County's drinking-water compliance score is 63.2 out of 100. The violation rate for Washington County is 4.6 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. Phosphorus, Total is the leading impairment cause in Washington County's watershed. With 108 active water-quality monitoring sites in Washington County, data coverage is strong.

Regional Context

Washington County has better water quality than the average county in Wisconsin. Its water score is 23.7 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 Washington County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    Phosphorus (excess nutrients)

    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

    Fecal coliform bacteria

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

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for Washington County

EPA How's My Waterway

Interactive watershed health data for Washington County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Washington County

Consumer Confidence Reports (WI)

Annual water quality reports from utilities in Wisconsin

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

10.8%

29 of 268 assessed

Some impairment

Top Impairment Causes

  • 1

    PHOSPHORUS, TOTAL

  • 2

    TOTAL SUSPENDED SOLIDS (TSS)

  • 3

    FECAL COLIFORM

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

108

Active in the past 5 years

Measurements Recorded

283K

282,771 total readings

Most Measured

  • Physical
  • Nutrient
  • Organics, Pesticide

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).

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Annual Total

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Filter Cost

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Safety Grade for Washington 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 Washington County, Wisconsin?
Washington County, Wisconsin has a drinking-water quality grade of B with a score of 63.2/100, based on EPA SDWIS compliance data. The county has 4 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 Washington County?
Washington County has 4 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 Washington County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 10.8% of Washington County's 268 assessed water bodies are classified as impaired (29 impaired). The top reported causes are PHOSPHORUS, TOTAL, TOTAL SUSPENDED SOLIDS (TSS), FECAL COLIFORM. 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 Washington County?
EPA's Water Quality Portal records 282,771 measurements from 108 monitoring sites in Washington County over the past five years. The most frequently measured characteristic groups are Physical, Nutrient, Organics, Pesticide. 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.
How does Washington County water compare to the Wisconsin average?
Washington County's SDWIS water quality score of 63.2/100 is higher than the Wisconsin state average of 39.5. The average water quality grade across Wisconsin is F, based on data from 71 counties with available SDWIS data.
Is tap water safe to drink in Washington County?
Based on EPA SDWIS data, Washington County has a water quality grade of B (63.2/100). 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).
Does Washington County have clean drinking water?
Washington County has 4 health-based drinking water violations according to EPA records. With a water quality score of 63.2/100 and grade B, the county's drinking water has had some compliance issues but continues to be monitored. Note: drinking-water compliance speaks to the public water system, not necessarily to the watershed itself — check the Watershed Health zone for ATTAINS §303(d) data.
How does Washington County rank for water quality in Wisconsin?
Washington County ranks #8 out of 71 counties in Wisconsin by SDWIS water quality score (1 = best). With a score of 63.2/100, 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

Racine County

Wisconsin

B

63.2

Water score

Brown County

Wisconsin

B

62.3

Water score

La Crosse County

Wisconsin

C

61.5

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.

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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