County water report

Rock Island County Water Report

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

Water grade

Water score

53.1

State rank

#44

of 102

Health violations

EPA SDWIS, 5-year lookback

Watershed impaired

41.6%

531 water bodies assessed

Monitoring sites

2,553 recent measurements

Live streamflow

145%

ROCK RIVER NEAR JOSLIN, IL

Water at a glance

Key Water Indicators for Rock Island County

EPA SDWIS

Safety Grade

Score: 53.1 / 100

EPA SDWIS

Active Violations

5-year health-based lookback

EPA ATTAINS

Watershed Health

42% impaired

531 bodies assessed

USGS NWIS

Streamflow Snapshot

145% of mean

ROCK RIVER NEAR JOSLIN, IL

EPA WQP

Monitoring Sites

2,553 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

53.1/100

Health violations

Health-based violations

Violations per 100K served

12.3

Population-normalized SDWIS rate

Data center water stress

Rock Island County has 1 facility in the DCWSI dataset.

ByCounty's DCWSI ranks this county #1470 nationally by combining its water score with mapped data center density.

DCWSI

31.9

0-100 index

Facility count

0.0 density percentile

Discharge estimate

Not reported

EPA CWA fields where available

Water vs median

+3.1

Compared with US county median

Mapped facilities

DEERE & CO
MOLINE
EPA ECHO

See the Rock Island County data-center report Review methodology

Data Center Water Budget Calculator

Estimate daily water use for a hypothetical facility in Rock Island County.

Facility size: 100 MW

1 MW1,000 MW

Cooling type

Utilization: 70%

40%100%

799K gallons/dayHigh Impact

Your facility would use 128.7% of this county's industrial water baseline. Verify water rights and long-term drought projections before committing.

128.7% of county industrial baseline

Based on USGS 2020 water-use data and EPA-standard cooling intensity constants. Not a substitute for site-specific water rights analysis.

Editorial analysis

Understanding Rock Island County’s Water

Drinking Water Quality Overview

EPA SDWIS

Rock Island County's drinking water earned a C grade, scoring 53.1 out of 100. Over the past five years, EPA SDWIS records 18 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 41.6% of assessed waterways are impaired (221 of 531 water bodies) across Rock Island County's watersheds. The leading impairment causes are phosphorus, total and total suspended solids (tss). 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 2026-05-14T12:45:00.000-06:00) puts ROCK RIVER at 10.6k cfs — flowing above its historical average at 145% 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. Rock Island County has limited coverage with 6 active monitoring sites with 2,553 recent measurements on record. Predominant monitoring categories include physical and inorganics, minor, metals. 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 Rock Island County

Water Verdict

Rock Island County, Illinois receives a below-average water quality assessment with a grade of C and a score of 53.1 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 531 water bodies in the county's watershed, with 41.6% 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 running above its historical mean at 145.3%.

Violation Context

EPA SDWIS records for Rock Island County, Illinois show 18 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 12.3 violations per 100,000 people served, this rate is high and signals significant water quality management issues. For independent context, 2,553 water-quality monitoring results have been recorded across the county in the EPA Water Quality Portal over the past five years.

Consumer Guidance

Tap water in Rock Island County meets baseline standards but the compliance record shows room for improvement, with a Grade C rating. Rock Island County's drinking-water compliance score is 53.1 out of 100. The violation rate for Rock Island County is 12.3 per 100,000 people served. Residents who are immunocompromised, pregnant, or have young children may benefit from using an NSF 53-certified filter. Contacting your local utility for the current Consumer Confidence Report will confirm which specific violations were recorded and whether they have been resolved. Phosphorus, Total is the leading impairment cause in Rock Island County's watershed. There are 6 active water-quality monitoring sites in Rock Island County. A pipeline streamflow snapshot from the ROCK RIVER gauge is also available on this page.

Regional Context

Rock Island County has better water quality than the average county in Illinois. Its water score is 5.3 points higher than the state average, indicating stronger water system performance relative to 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 Rock Island County's water environment

Watershed Impairment Causes (EPA ATTAINS)

1
Phosphorus (excess nutrients)
Impairment cause per EPA Clean Water Act §303(d) assessment
2
Total Suspended Solids (Tss)
Impairment cause per EPA Clean Water Act §303(d) assessment
3
Mercury
Impairment cause per EPA Clean Water Act §303(d) assessment

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for Rock Island County

EPA How's My Waterway

Interactive watershed health data for Rock Island County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Rock Island County

Consumer Confidence Reports (IL)

Annual water quality reports from utilities in Illinois

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

41.6%

221 of 531 assessed

Moderate concern

Top Impairment Causes

1
PHOSPHORUS, TOTAL
2
TOTAL SUSPENDED SOLIDS (TSS)
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

Active in the past 5 years

Measurements Recorded

2.6K

2,553 total readings

Most Measured

Physical
Inorganics, Minor, Metals
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

10.6Kcfs

May 14, 6:45 PM UTC

vs Long-Term Average

145%

Well above typical

Primary Streamgage

ROCK RIVER NEAR JOSLIN, IL

USGS site: 05446500
Drainage area: 9,549 sq mi
Long-term mean: 7,294 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

Household size

3 people · ~225 gal/day

Filter type

Annual Total

$558

Monthly

$47

Water Bill

$558/yr

Filter Cost

$0/yr

Safety Grade for Rock Island 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 Rock Island County, Illinois?

Rock Island County, Illinois has a drinking-water quality grade of C with a score of 53.1/100, based on EPA SDWIS compliance data. The county has 18 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 Rock Island County?

Rock Island County has 18 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 Rock Island County?

EPA ATTAINS assessments under Clean Water Act §303(d) indicate 41.6% of Rock Island County's 531 assessed water bodies are classified as impaired (221 impaired). The top reported causes are PHOSPHORUS, TOTAL, TOTAL SUSPENDED SOLIDS (TSS), 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 Rock Island County?

EPA's Water Quality Portal records 2,553 measurements from 6 monitoring sites in Rock Island County over the past five years. The most frequently measured characteristic groups are Physical, Inorganics, Minor, Metals, 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 Rock Island County right now?

Rock Island County's primary USGS streamgage on the ROCK RIVER has a pipeline snapshot of 10,600 cubic feet per second — 145% of the long-term mean of 7,294.22 cfs. This is well above typical — often a signal of recent precipitation or storm runoff. For the latest gauge feed, visit waterdata.usgs.gov.

How does Rock Island County water compare to the Illinois average?

Rock Island County's SDWIS water quality score of 53.1/100 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 Rock Island County?

Based on EPA SDWIS data, Rock Island County has a water quality grade of C (53.1/100). This indicates moderate compliance. Some violations have been recorded but overall standards are maintained. 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 Rock Island County have so many water violations?

Rock Island County has 18 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 Rock Island County rank for water quality in Illinois?

Rock Island County ranks #44 out of 102 counties in Illinois by SDWIS water quality score (1 = best). With a score of 53.1/100, 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

Hamilton County

Illinois

52.8

Water score

Whiteside County

Illinois

52.3

Water score

Knox County

Illinois

54.4

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.

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 May 14, 2026Reviewed by Evan Brooks, Data Editor

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