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EPA SDWIS

Calhoun County Water Quality

Calhoun County, Illinois

Water Grade

F

Water Score

40.7

Violations

2

State Rank

#59

of 102 (1 = best)

EPA SDWIS Compliance

Drinking Water Quality

Water Quality Grade

F

Based on EPA compliance history and violation data

Water Score

40.7/100

Higher = better quality

Health Violations

2

Health-based violations

Violation Rate

31.3%

Systems with violations

Water Advisory: Calhoun County

Water Verdict

Calhoun County receives a below-average water quality assessment with a grade of F and a score of 40.7 out of 100. Residents should review their utility's Consumer Confidence Report and may want to consider additional water filtration for drinking.

Violation Context

Calhoun County has recorded 2 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 31.3 violations per 1,000 residents, this rate is high and signals significant water quality management issues.

Consumer Guidance

Residents of Calhoun County are advised to use filtered or bottled water for drinking and cooking until water quality improves. A reverse-osmosis or activated-carbon filter certified to remove the contaminants listed in the utility's Consumer Confidence Report is recommended. With 2 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

Calhoun County has poorer water quality than the average county in Illinois. Its water score is 7.1 points lower than the state average, suggesting more challenges with contamination control or infrastructure than neighboring counties.

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

12.2%

23 of 188 assessed

Some impairment

Top Impairment Causes

  • 1

    MERCURY

  • 2

    FECAL COLIFORM

  • 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

3

Active in the past 5 years

Measurements Recorded

499

499 total readings

Most Measured

  • Inorganics, Minor, Metals
  • Physical
  • Nutrient

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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Frequently Asked Questions

What is the water quality in Calhoun County, Illinois?
Calhoun County, Illinois has a drinking-water quality grade of F with a score of 40.7/100, based on EPA SDWIS compliance data. The county has 2 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 Calhoun County?
Calhoun County has 2 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 Calhoun County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 12.2% of Calhoun County's 188 assessed water bodies are classified as impaired (23 impaired). The top reported causes are MERCURY, FECAL COLIFORM, 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 Calhoun County?
EPA's Water Quality Portal records 499 measurements from 3 monitoring sites in Calhoun County over the past five years. The most frequently measured characteristic groups are Inorganics, Minor, Metals, Physical, Nutrient. 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 Calhoun County water compare to the Illinois average?
Calhoun County's SDWIS water quality score of 40.7/100 is lower than the Illinois state average of 47.8. The average water quality grade across Illinois is D, based on data from 102 counties with available SDWIS data.
Is tap water safe to drink in Calhoun County?
Based on EPA SDWIS data, Calhoun County has a water quality grade of F (40.7/100). 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 Calhoun County have clean drinking water?
Calhoun County has 2 health-based drinking water violations according to EPA records. With a water quality score of 40.7/100 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 Calhoun County rank for water quality in Illinois?
Calhoun County ranks #59 out of 102 counties in Illinois by SDWIS water quality score (1 = best). With a score of 40.7/100, 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

Saline County

Illinois

F

40.7

Water score

Pulaski County

Illinois

F

41.0

Water score

Grundy County

Illinois

F

41.2

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, 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 Logan Johnson, Founder & Data EditorUpdated Reviewed by Logan Johnson, Founder & Data Editor

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