waterbycounty
EPA SDWIS

Winona County Water Quality

Winona County, Minnesota

Water Grade

C

Water Score

58.6

Violations

3

State Rank

#60

of 87 (1 = best)

EPA SDWIS Compliance

Drinking Water Quality

Water Quality Grade

C

Based on EPA compliance history and violation data

Water Score

58.6/100

Higher = better quality

Health Violations

3

Health-based violations

Violation Rate

7.5%

Systems with violations

Water Advisory: Winona County

Water Verdict

Winona County receives a fair water quality assessment with a grade of C and a score of 58.6 out of 100. The water supply meets baseline federal standards, but there may be periods of elevated contaminant levels or infrastructure concerns worth monitoring.

Violation Context

Winona County has recorded 3 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 7.5 violations per 1,000 residents, this rate is moderate and suggests recurring water quality challenges.

Consumer Guidance

Tap water in Winona County meets baseline standards, but residents who are immunocompromised or have young children may want to use an NSF-certified water filter as a precaution. With 3 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

Winona County has poorer water quality than the average county in Minnesota. Its water score is 8.6 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

0.0%

0 of 2 assessed

Mostly healthy

Top Impairment Causes

No specific impairment causes reported for this county's assessed water bodies.

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

104

Active in the past 5 years

Measurements Recorded

19K

19,247 total readings

Most Measured

  • Physical
  • Organics, Pesticide
  • 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

37.2Kcfs

May 14, 6:15 PM UTC

vs Long-Term Average

119%

Above typical

Primary Streamgage

MISSISSIPPI RIVER AT WINONA, MN

USGS site
05378500
Drainage area
59,200 sq mi
Long-term mean
31.3K 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 Winona County, Minnesota?
Winona County, Minnesota has a drinking-water quality grade of C with a score of 58.6/100, based on EPA SDWIS compliance data. The county has 3 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 Winona County?
Winona County has 3 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 Winona County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 0.0% of Winona County's 2 assessed water bodies are classified as impaired (0 impaired). 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 Winona County?
EPA's Water Quality Portal records 19,247 measurements from 104 monitoring sites in Winona County over the past five years. The most frequently measured characteristic groups are Physical, Organics, Pesticide, 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 Winona County right now?
Winona County's primary USGS streamgage on the MISSISSIPPI RIVER is currently reading 37,200 cubic feet per second — 119% of the long-term mean of 31,319.79 cfs. Flow is within typical range for this gauge. For genuine real-time data, visit waterdata.usgs.gov.
How does Winona County water compare to the Minnesota average?
Winona County's SDWIS water quality score of 58.6/100 is lower than the Minnesota state average of 67.2. The average water quality grade across Minnesota is C, based on data from 87 counties with available SDWIS data.
Is tap water safe to drink in Winona County?
Based on EPA SDWIS data, Winona County has a water quality grade of C (58.6/100). 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).
Does Winona County have clean drinking water?
Winona County has 3 health-based drinking water violations according to EPA records. With a water quality score of 58.6/100 and grade C, 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 Winona County rank for water quality in Minnesota?
Winona County ranks #60 out of 87 counties in Minnesota by SDWIS water quality score (1 = best). With a score of 58.6/100, 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

Scott County

Minnesota

C

59.8

Water score

Steele County

Minnesota

C

59.8

Water score

St. Louis County

Minnesota

C

57.2

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.

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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