waterbycounty
EPA SDWIS

Alexander County Water Quality

Alexander County, Illinois

Water Grade

A

Water Score

86.0

Violations

0

State Rank

#1

of 102 (1 = best)

EPA SDWIS Compliance

Drinking Water Quality

Water Quality Grade

A

Based on EPA compliance history and violation data

Water Score

86/100

Higher = better quality

Health Violations

0

Health-based violations

Violation Rate

0.0%

Systems with violations

Water Advisory: Alexander County

Water Verdict

Alexander County receives an excellent water quality assessment with a grade of A and a score of 86.0 out of 100. The water supply meets or exceeds federal safety standards, and residents can generally drink tap water with confidence.

Violation Context

Alexander County has recorded zero health-based violations, indicating that the water system has met all federal safety standards during the reporting period. The violation rate is zero per 1,000 residents, which is the best possible outcome.

Consumer Guidance

Tap water in Alexander 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. 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

Alexander County has better water quality than the average county in Illinois. Its water score is 38.2 points higher than the state average, indicating stronger water system performance relative to neighboring counties.

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

43.8%

64 of 146 assessed

Moderate concern

Top Impairment Causes

  • 1

    DISSOLVED OXYGEN

  • 2

    ALTERATION IN STREAM-SIDE OR LITTORAL VEGETATIVE COVERS

  • 3

    MERCURY

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

14K

14,086 total readings

Most Measured

  • Organics, Pesticide
  • 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).

Live USGS Streamgage

River & Stream Conditions

Current Discharge

286.0Kcfs

May 14, 7:00 PM UTC

vs Long-Term Average

130%

Well above typical

Primary Streamgage

Mississippi River at Thebes, IL

USGS site
07022000
Drainage area
713,200 sq mi
Long-term mean
220.0K 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 Alexander County, Illinois?
Alexander County, Illinois has a drinking-water quality grade of A with a score of 86.0/100, based on EPA SDWIS compliance data. The county has 0 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 Alexander County?
Alexander County has 0 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). Zero violations is an excellent record indicating consistent compliance with federal drinking water standards.
How healthy are the watersheds in Alexander County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 43.8% of Alexander County's 146 assessed water bodies are classified as impaired (64 impaired). The top reported causes are DISSOLVED OXYGEN, ALTERATION IN STREAM-SIDE OR LITTORAL VEGETATIVE COVERS, MERCURY. 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 Alexander County?
EPA's Water Quality Portal records 14,086 measurements from 3 monitoring sites in Alexander County over the past five years. The most frequently measured characteristic groups are Organics, Pesticide, 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.
What's happening with rivers in Alexander County right now?
Alexander County's primary USGS streamgage on the Mississippi River is currently reading 286,000 cubic feet per second — 130% of the long-term mean of 219,982.7 cfs. This is well above typical — often a signal of recent precipitation or storm runoff. For genuine real-time data, visit waterdata.usgs.gov.
How does Alexander County water compare to the Illinois average?
Alexander County's SDWIS water quality score of 86.0/100 is higher 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 Alexander County?
Based on EPA SDWIS data, Alexander County has a water quality grade of A (86.0/100). 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 Alexander County have clean drinking water?
Alexander County has 0 health-based drinking water violations according to EPA records. With a water quality score of 86.0/100 and grade A, the county's drinking water meets EPA standards with no recorded health violations. 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 Alexander County rank for water quality in Illinois?
Alexander County ranks #1 out of 102 counties in Illinois by SDWIS water quality score (1 = best). With a score of 86.0/100, 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

Boone County

Illinois

A

86.0

Water score

Brown County

Illinois

A

86.0

Water score

Clay County

Illinois

A

86.0

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.

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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