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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, Missouri.

Water grade

F

Water score

41.0

State rank

#64

of 115

Health violations

1

EPA SDWIS, 5-year lookback

Watershed impaired

Not reported

EPA ATTAINS coverage varies by state

Monitoring sites

9

784 recent measurements

Live streamflow

48%

Osage River at Taberville, MO

Water at a glance

Key Water Indicators for St. Clair County

EPA SDWIS

Safety Grade

F

Score: 41.0 / 100

EPA SDWIS

Active Violations

1

5-year health-based lookback

EPA ATTAINS

Watershed Health

Not reported

Coverage varies by state

USGS NWIS

Streamflow Snapshot

48% of mean

Osage River at Taberville, MO

EPA WQP

Monitoring Sites

9

784 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

F

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

41.0/100

Health violations

1

Health-based violations

Violations per 100K served

30.5

Population-normalized SDWIS rate

Editorial analysis

Understanding St. Clair County’s Water

Drinking Water Quality Overview

EPA SDWIS

St. Clair County's water systems carry a failing grade, scoring 41.0 out of 100. Over the past five years, EPA SDWIS records 1 health-based violation — a single incident worth monitoring.

River & Streamflow Status

USGS NWIS

USGS NWIS gauge data (as of 2026-05-14T13:45:00.000-05:00) puts Osage River at 2.1k cfs — well below its long-term average at 48% 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. St. Clair County has limited coverage with 9 active monitoring sites with 784 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 St. Clair County

Water Verdict

St. Clair County receives a below-average water quality assessment with a grade of F and a score of 41.0 out of 100. Residents should review their utility's Consumer Confidence Report and may want to consider additional water filtration for drinking.

Violation Context

St. Clair County has recorded 1 health-based violation, meaning the water system experienced at least one exceedance of federal contaminant limits or treatment requirements. At 30.5 violations per 100,000 people served, this rate is high and signals significant water quality management issues.

Consumer Guidance

Drinking-water compliance in St. Clair County is rated Grade F, reflecting significant health-based violations in the recent reporting period. St. Clair County's drinking-water compliance score is 41.0 out of 100. The violation rate for St. Clair County is 30.5 per 100,000 people served. An NSF 53 or NSF 58-certified filter is recommended for drinking and cooking water. Check the Consumer Confidence Report from your utility to identify the specific contaminants and required corrective actions — utilities are legally required to notify customers of violations. There are 9 active water-quality monitoring sites in St. Clair County. A pipeline streamflow snapshot from the Osage River gauge is also available on this page.

Regional Context

St. Clair County has poorer water quality than the average county in Missouri. Its water score is 7.8 points lower than the state average, suggesting more challenges with contamination control or infrastructure than 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 (MO)

Annual water quality reports from utilities in Missouri

Past 5 years

Water Quality Monitoring

Monitoring Sites

9

Active in the past 5 years

Measurements Recorded

784

784 total readings

Most Measured

  • Physical
  • Nutrient
  • Inorganics, Major, Non-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

2,110cfs

May 14, 6:45 PM UTC

vs Long-Term Average

48%

Well below typical

Primary Streamgage

Osage River at Taberville, MO

USGS site
06918250
Drainage area
5,670 sq mi
Long-term mean
4,365 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:D — Poor

Elevated violations or significant watershed impairment.

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, Missouri?
St. Clair County, Missouri has a drinking-water quality grade of F with a score of 41.0/100, based on EPA SDWIS compliance data. The county has 1 health-based drinking water violation 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 1 health-based drinking water violation 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 784 measurements from 9 monitoring sites in St. Clair County over the past five years. The most frequently measured characteristic groups are Physical, Nutrient, Inorganics, Major, Non-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 Osage River has a pipeline snapshot of 2,110 cubic feet per second — 48% of the long-term mean of 4,365.38 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 St. Clair County water compare to the Missouri average?
St. Clair County's SDWIS water quality score of 41.0/100 is lower than the Missouri state average of 48.8. The average water quality grade across Missouri is D, based on data from 115 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 F (41.0/100). This indicates below-average compliance with significant violations. Residents may want to consider home water filtration or independent testing. 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 1 health-based drinking water violation according to EPA records. With a water quality score of 41.0/100 and grade F, 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 Missouri?
St. Clair County ranks #64 out of 115 counties in Missouri by SDWIS water quality score (1 = best). With a score of 41.0/100, 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

Montgomery County

Missouri

D

42.0

Water score

Dade County

Missouri

F

39.7

Water score

Saline County

Missouri

D

42.4

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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