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Federal water data

County water report

Pennington County Water Report

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

Water grade

F

Water score

41.3

State rank

#39

of 63

Health violations

36

EPA SDWIS, 5-year lookback

Watershed impaired

Not reported

EPA ATTAINS coverage varies by state

Monitoring sites

91

30,106 recent measurements

Live streamflow

18%

CHEYENNE RIVER NEAR WASTA, SD

Water at a glance

Key Water Indicators for Pennington County

EPA SDWIS

Safety Grade

F

Score: 41.3 / 100

EPA SDWIS

Active Violations

36

5-year health-based lookback

EPA ATTAINS

Watershed Health

Not reported

Coverage varies by state

USGS NWIS

Streamflow Snapshot

18% of mean

CHEYENNE RIVER NEAR WASTA, SD

EPA WQP

Monitoring Sites

91

30,106 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.

41.3/100

Health violations

36

Health-based violations

Violations per 100K served

30.2

Population-normalized SDWIS rate

Editorial analysis

Understanding Pennington County’s Water

Drinking Water Quality Overview

EPA SDWIS

Pennington County's water systems carry a failing grade, scoring 41.3 out of 100. Over the past five years, EPA SDWIS records 36 health-based violations — a pattern that public water utilities are required to disclose and correct.

River & Streamflow Status

USGS NWIS

USGS NWIS gauge data (as of 2026-05-14T13:00:00.000-06:00) puts CHEYENNE RIVER at 66.8 cfs — well below its long-term average at 18% 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. Pennington County has extensive coverage with 91 active monitoring sites with 30,106 recent measurements on record. Predominant monitoring categories include organics, pesticide and organics, other. 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 Pennington County

Water Verdict

Pennington County receives a below-average water quality assessment with a grade of F and a score of 41.3 out of 100. Residents should review their utility's Consumer Confidence Report and may want to consider additional water filtration for drinking.

Violation Context

Pennington County has recorded 36 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 30.2 violations per 100,000 people served, this rate is high and signals significant water quality management issues.

Consumer Guidance

Pennington County has a Grade F compliance record with 36 health-based violations — among the highest levels in the country. Pennington County's drinking-water compliance score is 41.3 out of 100. The violation rate for Pennington County is 30.2 per 100,000 people served. Residents are strongly advised to use a certified NSF 58 reverse-osmosis filter or bottled water for all drinking and cooking until violations are corrected. Contacting the South Dakota Department of Environmental Quality or Health can expedite utility compliance action. With 91 active water-quality monitoring sites in Pennington County, data coverage is strong. A pipeline streamflow snapshot from the CHEYENNE RIVER gauge is also available on this page.

Regional Context

Pennington County has poorer water quality than the average county in South Dakota. Its water score is 15.5 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 Pennington County's water environment

Official EPA Resources for Pennington County

EPA How's My Waterway

Interactive watershed health data for Pennington County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Pennington County

Consumer Confidence Reports (SD)

Annual water quality reports from utilities in South Dakota

Past 5 years

Water Quality Monitoring

Monitoring Sites

91

Active in the past 5 years

Measurements Recorded

30K

30,106 total readings

Most Measured

  • Organics, Pesticide
  • Organics, Other
  • Physical

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

66.8cfs

May 14, 7:00 PM UTC

vs Long-Term Average

18%

Well below typical

Primary Streamgage

CHEYENNE RIVER NEAR WASTA, SD

USGS site
06423500
Drainage area
12,679 sq mi
Long-term mean
373 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 Pennington County:D — Poor

Elevated violations or significant watershed impairment.

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 Pennington County, South Dakota?
Pennington County, South Dakota has a drinking-water quality grade of F with a score of 41.3/100, based on EPA SDWIS compliance data. The county has 36 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 Pennington County?
Pennington County has 36 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 much water-quality monitoring happens in Pennington County?
EPA's Water Quality Portal records 30,106 measurements from 91 monitoring sites in Pennington County over the past five years. The most frequently measured characteristic groups are Organics, Pesticide, Organics, Other, Physical. 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 Pennington County right now?
Pennington County's primary USGS streamgage on the CHEYENNE RIVER has a pipeline snapshot of 66.8 cubic feet per second — 18% of the long-term mean of 373.18 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 Pennington County water compare to the South Dakota average?
Pennington County's SDWIS water quality score of 41.3/100 is lower than the South Dakota state average of 56.8. The average water quality grade across South Dakota is D, based on data from 63 counties with available SDWIS data.
Is tap water safe to drink in Pennington County?
Based on EPA SDWIS data, Pennington County has a water quality grade of F (41.3/100). 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 Pennington County have so many water violations?
Pennington County has 36 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 Pennington County rank for water quality in South Dakota?
Pennington County ranks #39 out of 63 counties in South Dakota by SDWIS water quality score (1 = best). With a score of 41.3/100, 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

Yankton County

South Dakota

F

41.3

Water score

Meade County

South Dakota

F

38.9

Water score

Edmunds County

South Dakota

F

38.8

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.

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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