waterbycounty
EPA SDWIS

Minnehaha County Water Quality

Minnehaha County, South Dakota

Water Grade

A

Water Score

70.4

Violations

2

State Rank

#29

of 63 (1 = best)

EPA SDWIS Compliance

Drinking Water Quality

Water Quality Grade

A

Based on EPA compliance history and violation data

Water Score

70.4/100

Higher = better quality

Health Violations

2

Health-based violations

Violation Rate

0.8%

Systems with violations

Water Advisory: Minnehaha County

Water Verdict

Minnehaha County receives a good water quality assessment with a grade of A and a score of 70.4 out of 100. While the water supply is generally safe, occasional monitoring gaps or minor contaminant detections may occur.

Violation Context

Minnehaha County has recorded 2 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 0.8 violations per 1,000 residents, this rate is relatively low compared to many U.S. counties.

Consumer Guidance

Tap water in Minnehaha County is generally safe to drink based on available data. Residents should still review their utility's annual Consumer Confidence Report for transparency on detected contaminants. With 2 recorded health violations, staying informed about utility communications and boil-water notices is especially important. For long-term peace of mind, request your utility's latest Consumer Confidence Report and consider independent water testing if you have specific health concerns.

Regional Context

Minnehaha County has better water quality than the average county in South Dakota. Its water score is 13.6 points higher than the state average, indicating stronger water system performance relative to neighboring counties.

Past 5 years

Water Quality Monitoring

Monitoring Sites

34

Active in the past 5 years

Measurements Recorded

3.0K

2,989 total readings

Most Measured

  • Physical
  • Nutrient
  • Microbiological

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

414cfs

May 14, 6:30 PM UTC

vs Long-Term Average

51%

Well below typical

Primary Streamgage

BIG SIOUX R AT NORTH CLIFF AVE AT SIOUX FALLS,SD

USGS site
06482020
Drainage area
4,662 sq mi
Long-term mean
813 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; "% of typical" compares the latest reading against that average.

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Frequently Asked Questions

What is the water quality in Minnehaha County, South Dakota?
Minnehaha County, South Dakota has a drinking-water quality grade of A with a score of 70.4/100, 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 live streamflow are reported separately on this page.
Are there any water violations in Minnehaha County?
Minnehaha 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 much water-quality monitoring happens in Minnehaha County?
EPA's Water Quality Portal records 2,989 measurements from 34 monitoring sites in Minnehaha County over the past five years. The most frequently measured characteristic groups are Physical, Nutrient, Microbiological. 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 Minnehaha County right now?
Minnehaha County's primary USGS streamgage on the BIG SIOUX R is currently reading 414 cubic feet per second — 51% of the long-term mean of 813.4 cfs. This is well below typical — often a signal of drought stress on source water. For genuine real-time data, visit waterdata.usgs.gov.
How does Minnehaha County water compare to the South Dakota average?
Minnehaha County's SDWIS water quality score of 70.4/100 is higher 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 Minnehaha County?
Based on EPA SDWIS data, Minnehaha County has a water quality grade of A (70.4/100). 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 Minnehaha County have clean drinking water?
Minnehaha County has 2 health-based drinking water violations according to EPA records. With a water quality score of 70.4/100 and grade 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 does Minnehaha County rank for water quality in South Dakota?
Minnehaha County ranks #29 out of 63 counties in South Dakota by SDWIS water quality score (1 = best). With a score of 70.4/100, 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

Codington County

South Dakota

B

64.1

Water score

Clay County

South Dakota

C

57.7

Water score

Brookings County

South Dakota

C

57.2

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 Logan Johnson, Founder & Data EditorUpdated Reviewed by Logan Johnson, Founder & Data Editor

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