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Federal water data

County water report

Union County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for Union County, Illinois.

Water grade

F

Water score

9.7

State rank

#102

of 102

Health violations

46

EPA SDWIS, 5-year lookback

Watershed impaired

44.3%

106 water bodies assessed

Monitoring sites

3

142 recent measurements

Live streamflow

No gauge

Primary USGS station not mapped

Water at a glance

Key Water Indicators for Union County

EPA SDWIS

Safety Grade

F

Score: 9.7 / 100

EPA SDWIS

Active Violations

46

5-year health-based lookback

EPA ATTAINS

Watershed Health

44% impaired

106 bodies assessed

USGS NWIS

Streamflow Snapshot

No gauge

Primary USGS gauge not mapped

EPA WQP

Monitoring Sites

3

142 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.

9.7/100

Health violations

46

Health-based violations

Violations per 100K served

349.2

Population-normalized SDWIS rate

Editorial analysis

Understanding Union County’s Water

Drinking Water Quality Overview

EPA SDWIS

Union County's water systems carry a failing grade, scoring 9.7 out of 100. Over the past five years, EPA SDWIS records 46 health-based violations — a pattern that public water utilities are required to disclose and correct.

Watershed Conditions

EPA ATTAINS

Under the Clean Water Act §303(d), EPA ATTAINS tracks whether waterways meet quality standards for drinking, recreation, and aquatic life (reporting cycle: 2022). A substantial 44.3% of assessed waterways are impaired (47 of 106 water bodies) across Union County's watersheds. The leading impairment causes are dissolved oxygen and mercury. Impairment does not mean tap water is unsafe — it measures ambient waterway conditions upstream of treatment, not finished drinking water.

Monitoring Network

EPA WQP

EPA's Water Quality Portal (WQP) aggregates monitoring data from federal, state, and tribal agencies. Union County has limited coverage with 3 active monitoring sites with 142 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 Union County

Water Verdict

Union County, Illinois receives a poor water quality assessment with a grade of F and a score of 9.7 out of 100. The water supply has documented quality issues. Residents are strongly encouraged to use filtered or bottled water for drinking and to stay informed about utility improvement plans. Separately, EPA ATTAINS assessments cover 106 water bodies in the county's watershed, with 44.3% listed as impaired under the Clean Water Act — a source-water measure that is tracked independently of tap-water compliance.

Violation Context

EPA SDWIS records for Union County, Illinois show 46 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 349.2 violations per 100,000 people served, this rate is high and signals significant water quality management issues. Independent monitoring is comparatively sparse here — 142 water-quality results logged in the EPA Water Quality Portal over the past five years — so the utility's own reporting carries extra weight.

Consumer Guidance

Union County has a Grade F compliance record with 46 health-based violations — among the highest levels in the country. Union County's drinking-water compliance score is 9.7 out of 100. Residents are strongly advised to use a certified NSF 58 reverse-osmosis filter or bottled water for all drinking and cooking until violations are corrected. Contacting the Illinois Department of Environmental Quality or Health can expedite utility compliance action. Dissolved Oxygen is the leading impairment cause in Union County's watershed. There are 3 active water-quality monitoring sites in Union County.

Regional Context

Union County has poorer water quality than the average county in Illinois. Its water score is 38.1 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 Union County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    Low dissolved oxygen

    Impairment cause per EPA Clean Water Act §303(d) assessment

  • 2

    Mercury

    Impairment cause per EPA Clean Water Act §303(d) assessment

  • 3

    Alteration in Stream-Side Or Littoral Vegetative Covers

    Impairment cause per EPA Clean Water Act §303(d) assessment

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for Union County

EPA How's My Waterway

Interactive watershed health data for Union County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Union County

Consumer Confidence Reports (IL)

Annual water quality reports from utilities in Illinois

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

44.3%

47 of 106 assessed

Moderate concern

Top Impairment Causes

  • 1

    DISSOLVED OXYGEN

  • 2

    MERCURY

  • 3

    ALTERATION IN STREAM-SIDE OR LITTORAL VEGETATIVE COVERS

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

142

142 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).

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 Union 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 Union County, Illinois?
Union County, Illinois has a drinking-water quality grade of F with a score of 9.7/100, based on EPA SDWIS compliance data. The county has 46 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 Union County?
Union County has 46 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 Union County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 44.3% of Union County's 106 assessed water bodies are classified as impaired (47 impaired). The top reported causes are DISSOLVED OXYGEN, MERCURY, ALTERATION IN STREAM-SIDE OR LITTORAL VEGETATIVE COVERS. 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 Union County?
EPA's Water Quality Portal records 142 measurements from 3 monitoring sites in Union 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.
How does Union County water compare to the Illinois average?
Union County's SDWIS water quality score of 9.7/100 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 Union County?
Based on EPA SDWIS data, Union County has a water quality grade of F (9.7/100). 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).
Why does Union County have so many water violations?
Union County has 46 health-based drinking water violations on record from the EPA SDWIS database. A higher violation count can result from aging infrastructure, underfunded water utilities, agricultural runoff contamination, or industrial pollution. Counties with more water systems may also see more violations simply due to scale. Residents concerned about water quality should consider independent water testing and home filtration systems.
How does Union County rank for water quality in Illinois?
Union County ranks #102 out of 102 counties in Illinois by SDWIS water quality score (1 = best). With a score of 9.7/100, it falls in the bottom 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

Bond County

Illinois

F

11.9

Water score

Scott County

Illinois

F

11.9

Water score

Pope County

Illinois

F

12.9

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 and 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 Evan Brooks, Data EditorUpdated Reviewed by Evan Brooks, Data Editor

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