waterbycounty
EPA SDWIS

St. Clair County Water Quality

St. Clair County, Michigan

Water Grade

B

Water Score

65.6

Violations

4

State Rank

#33

of 83 (1 = best)

EPA SDWIS Compliance

Drinking Water Quality

Water Quality Grade

B

Based on EPA compliance history and violation data

Water Score

65.6/100

Higher = better quality

Health Violations

4

Health-based violations

Violation Rate

3.2%

Systems with violations

Water Advisory: 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 1,000 residents, this rate is moderate and suggests recurring water quality challenges.

Consumer Guidance

Tap water in St. Clair County is generally safe to drink based on available data. Residents should still review their utility's annual Consumer Confidence Report for transparency on detected contaminants. With 4 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

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.

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; "% of typical" compares the latest reading against that average.

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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 live streamflow 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 is currently reading 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 genuine real-time data, 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 Logan Johnson, Founder & Data EditorUpdated Reviewed by Logan Johnson, Founder & Data Editor

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