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County water report

Mercer County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for Mercer County, North Dakota.

Water grade

A

Water score

86.0

State rank

#21

of 52

Health violations

0

EPA SDWIS, 5-year lookback

Watershed impaired

32.6%

46 water bodies assessed

Monitoring sites

37

11,964 recent measurements

Live streamflow

No gauge

KNIFE RIVER NR STANTON, ND

Water at a glance

Key Water Indicators for Mercer County

EPA SDWIS

Safety Grade

A

Score: 86.0 / 100

EPA SDWIS

Active Violations

0

5-year health-based lookback

EPA ATTAINS

Watershed Health

33% impaired

46 bodies assessed

USGS NWIS

Streamflow Snapshot

No gauge

KNIFE RIVER NR STANTON, ND

EPA WQP

Monitoring Sites

37

11,964 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

A

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

86.0/100

Health violations

0

Health-based violations

Violations per 100K served

0.0

Population-normalized SDWIS rate

Editorial analysis

Understanding Mercer County’s Water

Drinking Water Quality Overview

EPA SDWIS

Mercer County earns an A grade for drinking water quality, scoring 86.0 out of 100. EPA's Safe Drinking Water Information System (SDWIS) records zero health-based violations over the past five years — a strong compliance signal for a mid-sized county.

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 (15 of 46 water bodies) across Mercer County's watersheds. The leading impairment causes are escherichia coli (e. coli) and fecal coliform. 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. Mercer County has moderate coverage with 37 active monitoring sites with 11,964 recent measurements on record. Predominant monitoring categories include nutrient 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 Mercer County

Water Verdict

Mercer County, North Dakota receives an excellent water quality assessment with a grade of A and a score of 86.0 out of 100. The water supply meets or exceeds federal safety standards, and residents can generally drink tap water with confidence. Separately, EPA ATTAINS assessments cover 46 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.

Violation Context

EPA SDWIS records for Mercer County, North Dakota show zero health-based violations, indicating that the county's water systems met all federal safety standards during the reporting period. The violation rate is zero per 100,000 people served, which is the best possible outcome. This compliance record sits alongside an unusually deep monitoring archive: 11,964 water-quality results have been logged across the county in the EPA Water Quality Portal over the past five years.

Consumer Guidance

The EPA compliance record for Mercer County shows no recent health-based violations. Mercer County's drinking-water compliance score is 86.0 out of 100. Watershed monitoring does show E. coli in local surface water — a reminder that treated drinking water and source-water quality are measured separately. Reviewing your utility's annual Consumer Confidence Report each July confirms that treatment is keeping pace with any upstream pressures. With 37 active water-quality monitoring sites in Mercer County, data coverage is strong. A pipeline streamflow snapshot from the KNIFE RIVER gauge is also available on this page.

Regional Context

Mercer County has better water quality than the average county in North Dakota. Its water score is 14.4 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 Mercer County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    E. coli (bacteria)

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

  • 2

    Fecal coliform bacteria

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

  • 3

    Methylmercury

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

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for Mercer County

EPA How's My Waterway

Interactive watershed health data for Mercer County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Mercer County

Consumer Confidence Reports (ND)

Annual water quality reports from utilities in North Dakota

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

32.6%

15 of 46 assessed

Moderate concern

Top Impairment Causes

  • 1

    ESCHERICHIA COLI (E. COLI)

  • 2

    FECAL COLIFORM

  • 3

    METHYLMERCURY

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

37

Active in the past 5 years

Measurements Recorded

12K

11,964 total readings

Most Measured

  • Nutrient
  • Physical
  • Inorganics, Minor, 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

47.2cfs

Nov 6, 6:30 PM UTC

vs Long-Term Average

Long-term average not yet available.

Primary Streamgage

KNIFE RIVER NR STANTON, ND

USGS site
06340590
Drainage area
2,500 sq mi

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 Mercer 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 →

Mercer County has good water quality

Learn about water restrictions and conservation in your area.

Water Restrictions →

Frequently Asked Questions

What is the water quality in Mercer County, North Dakota?
Mercer County, North Dakota has a drinking-water quality grade of A with a score of 86.0/100, based on EPA SDWIS compliance data. The county has 0 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 Mercer County?
Mercer County has 0 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). Zero violations is an excellent record indicating consistent compliance with federal drinking water standards.
How healthy are the watersheds in Mercer County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 32.6% of Mercer County's 46 assessed water bodies are classified as impaired (15 impaired). The top reported causes are ESCHERICHIA COLI (E. COLI), FECAL COLIFORM, METHYLMERCURY. 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 Mercer County?
EPA's Water Quality Portal records 11,964 measurements from 37 monitoring sites in Mercer County over the past five years. The most frequently measured characteristic groups are Nutrient, Physical, Inorganics, Minor, 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 Mercer County right now?
Mercer County's primary USGS streamgage on the KNIFE RIVER has a pipeline snapshot of 47.2 cubic feet per second. Flow is within typical range for this gauge. For the latest gauge feed, visit waterdata.usgs.gov.
How does Mercer County water compare to the North Dakota average?
Mercer County's SDWIS water quality score of 86.0/100 is higher than the North Dakota state average of 71.6. The average water quality grade across North Dakota is C, based on data from 52 counties with available SDWIS data.
Is tap water safe to drink in Mercer County?
Based on EPA SDWIS data, Mercer County has a water quality grade of A (86.0/100). This indicates good to excellent water quality with strong SDWIS compliance. 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 Mercer County have clean drinking water?
Mercer County has 0 health-based drinking water violations according to EPA records. With a water quality score of 86.0/100 and grade A, the county's drinking water meets EPA standards with no recorded health violations. 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 Mercer County rank for water quality in North Dakota?
Mercer County ranks #21 out of 52 counties in North Dakota by SDWIS water quality score (1 = best). With a score of 86.0/100, 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

Adams County

North Dakota

A

86.0

Water score

Barnes County

North Dakota

A

86.0

Water score

Billings County

North Dakota

A

86.0

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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