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Federal water data

County water report

Williams County Water Report

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

Water grade

C

Water score

61.7

State rank

#40

of 52

Health violations

2

EPA SDWIS, 5-year lookback

Watershed impaired

6.7%

75 water bodies assessed

Monitoring sites

23

11,341 recent measurements

Live streamflow

30%

LITTLE MUDDY RIVER BL COW CREEK NR WILLISTON, ND

Water at a glance

Key Water Indicators for Williams County

EPA SDWIS

Safety Grade

C

Score: 61.7 / 100

EPA SDWIS

Active Violations

2

5-year health-based lookback

EPA ATTAINS

Watershed Health

7% impaired

75 bodies assessed

USGS NWIS

Streamflow Snapshot

30% of mean

LITTLE MUDDY RIVER BL COW CREEK NR WILLISTON, ND

EPA WQP

Monitoring Sites

23

11,341 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

C

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

61.7/100

Health violations

2

Health-based violations

Violations per 100K served

5.3

Population-normalized SDWIS rate

Editorial analysis

Understanding Williams County’s Water

Drinking Water Quality Overview

EPA SDWIS

Williams County's drinking water earned a C grade, scoring 61.7 out of 100. Over the past five years, EPA SDWIS records 2 health-based violations — a small cluster that warrants attention.

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 — 6.7% — of assessed waterways are impaired (5 of 75 water bodies) across Williams County's watersheds. The leading impairment causes are nutrients and fecal coliform. 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 2026-05-14T13:15:00.000-05:00) puts LITTLE MUDDY RIVER BL COW CREEK at 11.9 cfs — well below its long-term average at 30% of mean — low-flow conditions worth noting for water-dependent ecosystems. 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. Williams County has moderate coverage with 23 active monitoring sites with 11,341 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 Williams County

Water Verdict

Williams County receives a fair water quality assessment with a grade of C and a score of 61.7 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

Williams County has recorded 2 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 5.3 violations per 100,000 people served, this rate is moderate and suggests recurring water quality challenges.

Consumer Guidance

Tap water in Williams County meets baseline standards but the compliance record shows room for improvement, with a Grade C rating. Williams County's drinking-water compliance score is 61.7 out of 100. The violation rate for Williams County is 5.3 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. Nutrients is the leading impairment cause in Williams County's watershed. With 23 active water-quality monitoring sites in Williams County, data coverage is strong. A pipeline streamflow snapshot from the LITTLE MUDDY RIVER BL COW CREEK gauge is also available on this page.

Regional Context

Williams County has poorer water quality than the average county in North Dakota. Its water score is 9.9 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 Williams County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    Nutrient pollution

    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 Williams County

EPA How's My Waterway

Interactive watershed health data for Williams County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Williams County

Consumer Confidence Reports (ND)

Annual water quality reports from utilities in North Dakota

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

6.7%

5 of 75 assessed

Mostly healthy

Top Impairment Causes

  • 1

    NUTRIENTS

  • 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

23

Active in the past 5 years

Measurements Recorded

11K

11,341 total readings

Most Measured

  • Physical
  • Nutrient
  • 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

11.9cfs

May 14, 6:15 PM UTC

vs Long-Term Average

30%

Well below typical

Primary Streamgage

LITTLE MUDDY RIVER BL COW CREEK NR WILLISTON, ND

USGS site
06331000
Drainage area
875 sq mi
Long-term mean
40.4 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 Williams 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 Williams County, North Dakota?
Williams County, North Dakota has a drinking-water quality grade of C with a score of 61.7/100, based on EPA SDWIS compliance data. The county has 2 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 Williams County?
Williams County has 2 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 Williams County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 6.7% of Williams County's 75 assessed water bodies are classified as impaired (5 impaired). The top reported causes are NUTRIENTS, 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 Williams County?
EPA's Water Quality Portal records 11,341 measurements from 23 monitoring sites in Williams County over the past five years. The most frequently measured characteristic groups are Physical, Nutrient, 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 Williams County right now?
Williams County's primary USGS streamgage on the LITTLE MUDDY RIVER BL COW CREEK has a pipeline snapshot of 11.9 cubic feet per second — 30% of the long-term mean of 40.39 cfs. This is well below typical — often a signal of drought stress on source water. For the latest gauge feed, visit waterdata.usgs.gov.
How does Williams County water compare to the North Dakota average?
Williams County's SDWIS water quality score of 61.7/100 is lower 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 Williams County?
Based on EPA SDWIS data, Williams County has a water quality grade of C (61.7/100). 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 Williams County have clean drinking water?
Williams County has 2 health-based drinking water violations according to EPA records. With a water quality score of 61.7/100 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 Williams County rank for water quality in North Dakota?
Williams County ranks #40 out of 52 counties in North Dakota by SDWIS water quality score (1 = best). With a score of 61.7/100, 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

McKenzie County

North Dakota

C

57.5

Water score

Stutsman County

North Dakota

C

56.4

Water score

Cass County

North Dakota

B

69.7

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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