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Federal water data

County water report

Sioux County Water Report

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

Water grade

N/A

Water score

N/A

State rank

N/A

Health violations

N/A

EPA SDWIS, 5-year lookback

Watershed impaired

29.4%

17 water bodies assessed

Monitoring sites

8

1,436 recent measurements

Live streamflow

54%

CANNONBALL RIVER AT SOLEN, ND

Water at a glance

Key Water Indicators for Sioux County

EPA SDWIS

Safety Grade

N/A

Insufficient data

EPA SDWIS

Active Violations

N/A

5-year health-based lookback

EPA ATTAINS

Watershed Health

29% impaired

17 bodies assessed

USGS NWIS

Streamflow Snapshot

54% of mean

CANNONBALL RIVER AT SOLEN, ND

EPA WQP

Monitoring Sites

8

1,436 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Editorial analysis

Understanding Sioux County’s Water

Drinking Water Quality Overview

EPA SDWIS

Sioux County has limited drinking water data on file. Violation data are unavailable for this 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 notable 29.4% of assessed waterways carry an impairment designation (5 of 17 water bodies) across Sioux County's watersheds. The leading impairment causes are fecal coliform and escherichia coli (e. coli). 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 2026-05-14T13:00:00.000-05:00) puts CANNONBALL RIVER at 50.3 cfs — well below its long-term average at 54% 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. Sioux County has limited coverage with 8 active monitoring sites with 1,436 recent measurements on record. Predominant monitoring categories include physical and inorganics, major, non-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 Sioux County

Water Verdict

Sioux County does not have sufficient EPA SDWIS water quality data to determine an overall assessment. Residents should contact their local water utility for the most recent Consumer Confidence Report.

Violation Context

Health-based violation data is not available for Sioux County. EPA health violations occur when water systems exceed allowable contaminant levels or fail to meet treatment requirements. Residents should request the latest Consumer Confidence Report from their water provider.

Consumer Guidance

Drinking-water compliance data is not yet available for Sioux County in the EPA SDWIS system, which is common for rural areas and census areas served by private wells or small tribal systems. Residents should contact their local utility or state drinking-water agency for the most current Consumer Confidence Report. Using an NSF-certified filter (look for certifications against ANSI/NSF 53 or 58) can provide additional safety margin for any unconfirmed contaminants. Fecal Coliform is the leading impairment cause in Sioux County's watershed. A pipeline streamflow snapshot from the CANNONBALL RIVER gauge is also available on this page.

Regional Context

State-level water quality comparison data is not available for Sioux County. When data is available, this section will show how the county's water quality compares to other counties in North Dakota.

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 Sioux County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    Fecal coliform bacteria

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

  • 2

    E. coli (bacteria)

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

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for Sioux County

EPA How's My Waterway

Interactive watershed health data for Sioux County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Sioux County

Consumer Confidence Reports (ND)

Annual water quality reports from utilities in North Dakota

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

29.4%

5 of 17 assessed

Some impairment

Top Impairment Causes

  • 1

    FECAL COLIFORM

  • 2

    ESCHERICHIA COLI (E. COLI)

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

8

Active in the past 5 years

Measurements Recorded

1.4K

1,436 total readings

Most Measured

  • Physical
  • Inorganics, Major, Non-metals
  • Organics, Other

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

50.3cfs

May 14, 6:00 PM UTC

vs Long-Term Average

54%

Well below typical

Primary Streamgage

CANNONBALL RIVER AT SOLEN, ND

USGS site
06354050
Drainage area
4,170 sq mi
Long-term mean
93.4 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.

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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 Sioux County:F — Failing

High violation count or severe watershed conditions.

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 →

Sioux 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 Sioux County, North Dakota?
Sioux County, North Dakota has a drinking-water quality grade of N/A with a score of N/A/100, based on EPA SDWIS compliance data. Compliance data is currently unavailable. Watershed health, monitoring records, and streamflow snapshots are reported separately on this page.
Are there any water violations in Sioux County?
Violation data for Sioux County is not currently available. Health-based violations indicate instances where contaminant levels exceeded EPA Maximum Contaminant Levels (MCLs).
How healthy are the watersheds in Sioux County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 29.4% of Sioux County's 17 assessed water bodies are classified as impaired (5 impaired). The top reported causes are FECAL COLIFORM, ESCHERICHIA COLI (E. COLI). 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 Sioux County?
EPA's Water Quality Portal records 1,436 measurements from 8 monitoring sites in Sioux County over the past five years. The most frequently measured characteristic groups are Physical, Inorganics, Major, Non-metals, Organics, Other. 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 Sioux County right now?
Sioux County's primary USGS streamgage on the CANNONBALL RIVER has a pipeline snapshot of 50.3 cubic feet per second — 54% of the long-term mean of 93.4 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 Sioux County water compare to the North Dakota average?
Sioux County's SDWIS water quality score of N/A/100 is not available for comparison. 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 Sioux County?
Based on EPA SDWIS data, Sioux County has a water quality grade of N/A (N/A/100). Insufficient data is available to fully assess 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 Sioux County have clean drinking water?
Sioux County has no reported health-based drinking water violations according to EPA records. With a water quality score of N/A/100 and grade N/A, 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 is water quality measured?
WaterByCounty layers four federal datasets per county. The A–F drinking-water grade comes from EPA SDWIS (Safe Drinking Water Act compliance, 5-year violation lookback). The Watershed Health zone surfaces EPA ATTAINS §303(d) impairment data. The Monitoring zone summarizes EPA Water Quality Portal records. The Streamflow zone reports the latest USGS NWIS reading from the county's primary streamgage. Each is reported separately so you can see where the water is actually weakest.

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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