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County water report

Logan County Water Report

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

Water grade

D

Water score

41.6

State rank

#56

of 102

Health violations

7

EPA SDWIS, 5-year lookback

Watershed impaired

32.6%

181 water bodies assessed

Monitoring sites

5

1,931 recent measurements

Live streamflow

85%

LAKE FORK NEAR CORNLAND, IL

Water at a glance

Key Water Indicators for Logan County

EPA SDWIS

Safety Grade

D

Score: 41.6 / 100

EPA SDWIS

Active Violations

7

5-year health-based lookback

EPA ATTAINS

Watershed Health

33% impaired

181 bodies assessed

USGS NWIS

Streamflow Snapshot

85% of mean

LAKE FORK NEAR CORNLAND, IL

EPA WQP

Monitoring Sites

5

1,931 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

D

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

41.6/100

Health violations

7

Health-based violations

Violations per 100K served

29.2

Population-normalized SDWIS rate

Editorial analysis

Understanding Logan County’s Water

Drinking Water Quality Overview

EPA SDWIS

Logan County's drinking water received a D grade, scoring 41.6 out of 100. Over the past five years, EPA SDWIS records 7 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 32.6% of assessed waterways are impaired (59 of 181 water bodies) across Logan County's watersheds. The leading impairment causes are fecal coliform and mercury. Impairment does not mean tap water is unsafe — it measures ambient waterway conditions upstream of treatment, not finished drinking water.

River & Streamflow Status

USGS NWIS

USGS NWIS gauge data (as of 2026-05-14T12:30:00.000-06:00) puts LAKE FORK at 144.0 cfs — running somewhat below its historical average at 85% of mean. 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. Logan County has limited coverage with 5 active monitoring sites with 1,931 recent measurements on record. Predominant monitoring categories include inorganics, minor, metals and physical. 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 Logan County

Water Verdict

Logan County, Illinois receives a below-average water quality assessment with a grade of D and a score of 41.6 out of 100. Residents should review their utility's Consumer Confidence Report and may want to consider additional water filtration for drinking. Separately, EPA ATTAINS assessments cover 181 water bodies in the county's watershed, with 32.6% listed as impaired under the Clean Water Act — a source-water measure that is tracked independently of tap-water compliance. At the most recent USGS reading, local streamflow was below its historical mean at 85.3% — worth watching in drier seasons.

Violation Context

EPA SDWIS records for Logan County, Illinois show 7 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 29.2 violations per 100,000 people served, this rate is high and signals significant water quality management issues. For independent context, 1,931 water-quality monitoring results have been recorded across the county in the EPA Water Quality Portal over the past five years.

Consumer Guidance

Logan County's drinking-water compliance is below average with a Grade D, indicating repeated or unresolved violations in the recent record. Logan County's drinking-water compliance score is 41.6 out of 100. The violation rate for Logan County is 29.2 per 100,000 people served. Residents are encouraged to use an NSF 53 or NSF 58-certified filter for drinking and cooking water until the underlying violations are resolved. Running tap water for 30 seconds before use and avoiding older lead-pipe connections can also reduce exposure risk. The current Consumer Confidence Report from your utility will specify the contaminants of concern. Fecal Coliform is the leading impairment cause in Logan County's watershed. There are 5 active water-quality monitoring sites in Logan County. A pipeline streamflow snapshot from the LAKE FORK gauge is also available on this page.

Regional Context

Logan County has poorer water quality than the average county in Illinois. Its water score is 6.2 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 Logan County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    Fecal coliform bacteria

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

  • 2

    Mercury

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

  • 3

    Polychlorinated Biphenyls (Pcbs)

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

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for Logan County

EPA How's My Waterway

Interactive watershed health data for Logan County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Logan County

Consumer Confidence Reports (IL)

Annual water quality reports from utilities in Illinois

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

32.6%

59 of 181 assessed

Moderate concern

Top Impairment Causes

  • 1

    FECAL COLIFORM

  • 2

    MERCURY

  • 3

    POLYCHLORINATED BIPHENYLS (PCBS)

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

5

Active in the past 5 years

Measurements Recorded

1.9K

1,931 total readings

Most Measured

  • Inorganics, Minor, Metals
  • Physical
  • Inorganics, Major, 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

144cfs

May 14, 6:30 PM UTC

vs Long-Term Average

85%

Below typical

Primary Streamgage

LAKE FORK NEAR CORNLAND, IL

USGS site
05579500
Drainage area
214 sq mi
Long-term mean
169 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

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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 Logan 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 Logan County, Illinois?
Logan County, Illinois has a drinking-water quality grade of D with a score of 41.6/100, based on EPA SDWIS compliance data. The county has 7 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 Logan County?
Logan County has 7 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 Logan County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 32.6% of Logan County's 181 assessed water bodies are classified as impaired (59 impaired). The top reported causes are FECAL COLIFORM, MERCURY, POLYCHLORINATED BIPHENYLS (PCBS). 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 Logan County?
EPA's Water Quality Portal records 1,931 measurements from 5 monitoring sites in Logan County over the past five years. The most frequently measured characteristic groups are Inorganics, Minor, Metals, Physical, Inorganics, Major, 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 Logan County right now?
Logan County's primary USGS streamgage on the LAKE FORK has a pipeline snapshot of 144 cubic feet per second — 85% of the long-term mean of 168.76 cfs. Flow is within typical range for this gauge. For the latest gauge feed, visit waterdata.usgs.gov.
How does Logan County water compare to the Illinois average?
Logan County's SDWIS water quality score of 41.6/100 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 Logan County?
Based on EPA SDWIS data, Logan County has a water quality grade of D (41.6/100). 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 Logan County have so many water violations?
Logan County has 7 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 Logan County rank for water quality in Illinois?
Logan County ranks #56 out of 102 counties in Illinois by SDWIS water quality score (1 = best). With a score of 41.6/100, 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

Massac County

Illinois

D

41.8

Water score

Grundy County

Illinois

F

41.2

Water score

Pulaski County

Illinois

F

41.0

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 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.

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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