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County water report

St. Clair County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for St. Clair County, Michigan.

Water grade

B

Water score

65.6

State rank

#33

of 83

Health violations

4

EPA SDWIS, 5-year lookback

Watershed impaired

Not reported

EPA ATTAINS coverage varies by state

Monitoring sites

32

4,598 recent measurements

Live streamflow

111%

ST. CLAIR RIVER AT PORT HURON, MI

Water at a glance

Key Water Indicators for St. Clair County

EPA SDWIS

Safety Grade

B

Score: 65.6 / 100

EPA SDWIS

Active Violations

4

5-year health-based lookback

EPA ATTAINS

Watershed Health

Not reported

Coverage varies by state

USGS NWIS

Streamflow Snapshot

111% of mean

ST. CLAIR RIVER AT PORT HURON, MI

EPA WQP

Monitoring Sites

32

4,598 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.

65.6/100

Health violations

4

Health-based violations

Violations per 100K served

3.2

Population-normalized SDWIS rate

Editorial analysis

Understanding St. Clair County’s Water

Drinking Water Quality Overview

EPA SDWIS

St. Clair County earns a B grade for drinking water quality, scoring 65.6 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.

River & Streamflow Status

USGS NWIS

USGS NWIS gauge data (as of 2026-05-14T13:24:00.000-05:00) puts ST. CLAIR RIVER at 221.0k cfs — flowing above its historical average at 111% 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. St. Clair County has moderate coverage with 32 active monitoring sites with 4,598 recent measurements on record. Predominant monitoring categories include physical and microbiological. 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 St. Clair County

Water Verdict

St. Clair County receives a fair water quality assessment with a grade of B and a score of 65.6 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

St. Clair County has recorded 4 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 3.2 violations per 100,000 people served, this rate is moderate and suggests recurring water quality challenges.

Consumer Guidance

Tap water in St. Clair County meets baseline safety standards, though the compliance record shows some violations worth watching. St. Clair County's drinking-water compliance score is 65.6 out of 100. The violation rate for St. Clair County is 3.2 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. With 32 active water-quality monitoring sites in St. Clair County, data coverage is strong. Live streamflow monitoring from the ST. CLAIR RIVER gauge is also available on this page.

Regional Context

St. Clair County has better water quality than the average county in Michigan. Its water score is 7.1 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 St. Clair County's water environment

Official EPA Resources for St. Clair County

EPA How's My Waterway

Interactive watershed health data for St. Clair County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for St. Clair County

Consumer Confidence Reports (MI)

Annual water quality reports from utilities in Michigan

Past 5 years

Water Quality Monitoring

Monitoring Sites

32

Active in the past 5 years

Measurements Recorded

4.6K

4,598 total readings

Most Measured

  • Physical
  • Microbiological
  • Inorganics, Minor, Metals

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

221.0Kcfs

May 14, 6:24 PM UTC

vs Long-Term Average

111%

Above typical

Primary Streamgage

ST. CLAIR RIVER AT PORT HURON, MI

USGS site
04159130
Drainage area
222,400 sq mi
Long-term mean
199.5K 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 St. Clair 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 St. Clair County, Michigan?
St. Clair County, Michigan has a drinking-water quality grade of B with a score of 65.6/100, 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 St. Clair County?
St. Clair 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 much water-quality monitoring happens in St. Clair County?
EPA's Water Quality Portal records 4,598 measurements from 32 monitoring sites in St. Clair County over the past five years. The most frequently measured characteristic groups are Physical, Microbiological, Inorganics, Minor, Metals. 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 St. Clair County right now?
St. Clair County's primary USGS streamgage on the ST. CLAIR RIVER has a pipeline snapshot of 221,000 cubic feet per second — 111% of the long-term mean of 199,525 cfs. Flow is within typical range for this gauge. For the latest gauge feed, visit waterdata.usgs.gov.
How does St. Clair County water compare to the Michigan average?
St. Clair County's SDWIS water quality score of 65.6/100 is higher than the Michigan state average of 58.5. The average water quality grade across Michigan is D, based on data from 83 counties with available SDWIS data.
Is tap water safe to drink in St. Clair County?
Based on EPA SDWIS data, St. Clair County has a water quality grade of B (65.6/100). 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 St. Clair County have clean drinking water?
St. Clair County has 4 health-based drinking water violations according to EPA records. With a water quality score of 65.6/100 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 St. Clair County rank for water quality in Michigan?
St. Clair County ranks #33 out of 83 counties in Michigan by SDWIS water quality score (1 = best). With a score of 65.6/100, it falls in the middle 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

Houghton County

Michigan

B

65.3

Water score

Kent County

Michigan

B

64.8

Water score

Saginaw County

Michigan

B

64.8

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.

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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