waterbycounty
Federal water data

County water report

Oconto County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for Oconto County, Wisconsin.

Water grade

F

Water score

31.7

State rank

#47

of 71

Health violations

6

EPA SDWIS, 5-year lookback

Watershed impaired

2.1%

890 water bodies assessed

Monitoring sites

136

34,768 recent measurements

Live streamflow

103%

OCONTO RIVER NEAR OCONTO, WI

Water at a glance

Key Water Indicators for Oconto County

EPA SDWIS

Safety Grade

F

Score: 31.7 / 100

EPA SDWIS

Active Violations

6

5-year health-based lookback

EPA ATTAINS

Watershed Health

2% impaired

890 bodies assessed

USGS NWIS

Streamflow Snapshot

103% of mean

OCONTO RIVER NEAR OCONTO, WI

EPA WQP

Monitoring Sites

136

34,768 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.

31.7/100

Health violations

6

Health-based violations

Violations per 100K served

58.3

Population-normalized SDWIS rate

Editorial analysis

Understanding Oconto County’s Water

Drinking Water Quality Overview

EPA SDWIS

Oconto County's water systems carry a failing grade, scoring 31.7 out of 100. Over the past five years, EPA SDWIS records 6 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 small share — 2.1% — of assessed waterways are impaired (19 of 890 water bodies) across Oconto County's watersheds. The leading impairment causes are phosphorus, total and cause unknown. 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 2026-05-14T14:00:00.000-05:00) puts OCONTO RIVER at 739.0 cfs — near its historical average at 103% of mean flow. 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. Oconto County has extensive coverage with 136 active monitoring sites with 34,768 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 Oconto County

Water Verdict

Oconto County, Wisconsin receives a poor water quality assessment with a grade of F and a score of 31.7 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 890 water bodies in the county's watershed, with 2.1% 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 tracking near its historical mean (102.5%).

Violation Context

EPA SDWIS records for Oconto County, Wisconsin show 6 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 58.3 violations per 100,000 people served, this rate is high and signals significant water quality management issues. This compliance record sits alongside an unusually deep monitoring archive: 34,768 water-quality results have been logged across the county in the EPA Water Quality Portal over the past five years.

Consumer Guidance

Drinking-water compliance in Oconto County is rated Grade F, reflecting significant health-based violations in the recent reporting period. Oconto County's drinking-water compliance score is 31.7 out of 100. The violation rate for Oconto County is 58.3 per 100,000 people served. An NSF 53 or NSF 58-certified filter is recommended for drinking and cooking water. Check the Consumer Confidence Report from your utility to identify the specific contaminants and required corrective actions — utilities are legally required to notify customers of violations. Phosphorus, Total is the leading impairment cause in Oconto County's watershed. With 136 active water-quality monitoring sites in Oconto County, data coverage is strong. A pipeline streamflow snapshot from the OCONTO RIVER gauge is also available on this page.

Regional Context

Oconto County has poorer water quality than the average county in Wisconsin. Its water score is 7.8 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 Oconto County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    Phosphorus (excess nutrients)

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

  • 2

    Cause Unknown

    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 Oconto County

EPA How's My Waterway

Interactive watershed health data for Oconto County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Oconto County

Consumer Confidence Reports (WI)

Annual water quality reports from utilities in Wisconsin

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

2.1%

19 of 890 assessed

Mostly healthy

Top Impairment Causes

  • 1

    PHOSPHORUS, TOTAL

  • 2

    CAUSE UNKNOWN

  • 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

136

Active in the past 5 years

Measurements Recorded

35K

34,768 total readings

Most Measured

  • Physical
  • Nutrient
  • Organics, Pesticide

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

739cfs

May 14, 7:00 PM UTC

vs Long-Term Average

103%

Near typical

Primary Streamgage

OCONTO RIVER NEAR OCONTO, WI

USGS site
04071765
Drainage area
966 sq mi
Long-term mean
721 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

3

3 people  ·  ~225 gal/day

Annual Total

$558

Monthly

$47

Water Bill

$558/yr

Filter Cost

$0/yr

Safety Grade for Oconto 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.

Try the full calculator →

Improve your water quality at home

Berkey filters remove 99.9%+ of contaminants from tap water.

Shop Berkey →

Sponsored

Test your tap water

Tap Score provides professional mail-in water testing.

Get Tested →

Frequently Asked Questions

What is the water quality in Oconto County, Wisconsin?
Oconto County, Wisconsin has a drinking-water quality grade of F with a score of 31.7/100, based on EPA SDWIS compliance data. The county has 6 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 Oconto County?
Oconto County has 6 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 Oconto County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 2.1% of Oconto County's 890 assessed water bodies are classified as impaired (19 impaired). The top reported causes are PHOSPHORUS, TOTAL, CAUSE UNKNOWN, 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 Oconto County?
EPA's Water Quality Portal records 34,768 measurements from 136 monitoring sites in Oconto County over the past five years. The most frequently measured characteristic groups are Physical, Nutrient, Organics, Pesticide. 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 Oconto County right now?
Oconto County's primary USGS streamgage on the OCONTO RIVER has a pipeline snapshot of 739 cubic feet per second — 103% of the long-term mean of 720.63 cfs. Flow is within typical range for this gauge. For the latest gauge feed, visit waterdata.usgs.gov.
How does Oconto County water compare to the Wisconsin average?
Oconto County's SDWIS water quality score of 31.7/100 is lower than the Wisconsin state average of 39.5. The average water quality grade across Wisconsin is F, based on data from 71 counties with available SDWIS data.
Is tap water safe to drink in Oconto County?
Based on EPA SDWIS data, Oconto County has a water quality grade of F (31.7/100). 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 Oconto County have so many water violations?
Oconto County has 6 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 Oconto County rank for water quality in Wisconsin?
Oconto County ranks #47 out of 71 counties in Wisconsin by SDWIS water quality score (1 = best). With a score of 31.7/100, 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

Dodge County

Wisconsin

F

31.9

Water score

Richland County

Wisconsin

F

32.2

Water score

Washburn County

Wisconsin

F

31.1

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

Explore more data for Oconto County

Property TaxCost of LivingCrime RateIncomeHealthSchoolsDisaster RiskWeatherCounty Score