County water report

Olmsted County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for Olmsted County, Minnesota.

Water grade

Water score

86.0

State rank

#32

of 87

Health violations

EPA SDWIS, 5-year lookback

Watershed impaired

Not reported

EPA ATTAINS coverage varies by state

Monitoring sites

120

39,693 recent measurements

Live streamflow

65%

SOUTH FORK ZUMBRO RIVER AT ROCHESTER, MN

Water at a glance

Key Water Indicators for Olmsted County

EPA SDWIS

Safety Grade

Score: 86.0 / 100

EPA SDWIS

Active Violations

5-year health-based lookback

EPA ATTAINS

Watershed Health

Not reported

Coverage varies by state

USGS NWIS

Streamflow Snapshot

65% of mean

SOUTH FORK ZUMBRO RIVER AT ROCHESTER, MN

EPA WQP

Monitoring Sites

120

39,693 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

86.0/100

Health violations

Health-based violations

Violations per 100K served

0.0

Population-normalized SDWIS rate

Data center water stress

Olmsted County has 1 facility in the DCWSI dataset.

ByCounty's DCWSI ranks this county #160 nationally by combining its water score with mapped data center density.

DCWSI

51.6

0-100 index

Facility count

0.0 density percentile

Discharge estimate

Not reported

EPA CWA fields where available

Water vs median

+36.0

Compared with US county median

Mapped facilities

Epic / Mayo Data Center
Rochester
OSM

See the Olmsted County data-center report Review methodology

Data Center Water Budget Calculator

Estimate daily water use for a hypothetical facility in Olmsted County.

Facility size: 100 MW

1 MW1,000 MW

Cooling type

Utilization: 70%

40%100%

799K gallons/dayHigh Impact

Your facility would use 53.5% of this county's industrial water baseline. Verify water rights and long-term drought projections before committing.

53.5% of county industrial baseline0.69 Mgal/day remaining headroom

Based on USGS 2020 water-use data and EPA-standard cooling intensity constants. Not a substitute for site-specific water rights analysis.

Editorial analysis

Understanding Olmsted County’s Water

Drinking Water Quality Overview

EPA SDWIS

Olmsted 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 large county.

River & Streamflow Status

USGS NWIS

USGS NWIS gauge data (as of 2026-05-14T13:15:00.000-05:00) puts SOUTH FORK ZUMBRO RIVER at 154.0 cfs — running somewhat below its historical average at 65% of mean. 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. Olmsted County has extensive coverage with 120 active monitoring sites with 39,693 recent measurements on record. Predominant monitoring categories include physical and organics, pesticide. 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 Olmsted County

Water Verdict

Olmsted County, Minnesota 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. The county's primary USGS gauge drains roughly 303 square miles of upstream watershed, giving local source waters a regional footprint. At the most recent USGS reading, local streamflow was below its historical mean at 64.6% — worth watching in drier seasons.

Violation Context

EPA SDWIS records for Olmsted County, Minnesota 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: 39,693 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 Olmsted County shows no recent health-based violations. No health-based violations have been recorded, placing Olmsted County in the top tier for drinking-water safety. Olmsted County's drinking-water compliance score is 86.0 out of 100. As a routine precaution, requesting your utility's annual Consumer Confidence Report each July gives you a full list of detected contaminants and their treatment levels. With 120 active water-quality monitoring sites in Olmsted County, data coverage is strong. A pipeline streamflow snapshot from the SOUTH FORK ZUMBRO RIVER gauge is also available on this page.

Regional Context

Olmsted County has better water quality than the average county in Minnesota. Its water score is 18.8 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.

Past 5 years

Water Quality Monitoring

Monitoring Sites

120

Active in the past 5 years

Measurements Recorded

40K

39,693 total readings

Most Measured

Physical
Organics, Pesticide
Nutrient

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

154cfs

May 14, 6:15 PM UTC

vs Long-Term Average

65%

Below typical

Primary Streamgage

SOUTH FORK ZUMBRO RIVER AT ROCHESTER, MN

USGS site: 05372995
Drainage area: 303 sq mi
Long-term mean: 239 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

Household size

3 people · ~225 gal/day

Filter type

Annual Total

$558

Monthly

$47

Water Bill

$558/yr

Filter Cost

$0/yr

Safety Grade for Olmsted County:B — Good

Minor violations; waterways mostly healthy.

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 →

Olmsted 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 Olmsted County, Minnesota?

Olmsted County, Minnesota 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 Olmsted County?

Olmsted 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 much water-quality monitoring happens in Olmsted County?

EPA's Water Quality Portal records 39,693 measurements from 120 monitoring sites in Olmsted County over the past five years. The most frequently measured characteristic groups are Physical, Organics, Pesticide, Nutrient. 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 Olmsted County right now?

Olmsted County's primary USGS streamgage on the SOUTH FORK ZUMBRO RIVER has a pipeline snapshot of 154 cubic feet per second — 65% of the long-term mean of 238.51 cfs. Flow is within typical range for this gauge. For the latest gauge feed, visit waterdata.usgs.gov.

How does Olmsted County water compare to the Minnesota average?

Olmsted County's SDWIS water quality score of 86.0/100 is higher than the Minnesota state average of 67.2. The average water quality grade across Minnesota is C, based on data from 87 counties with available SDWIS data.

Is tap water safe to drink in Olmsted County?

Based on EPA SDWIS data, Olmsted 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 Olmsted County have clean drinking water?

Olmsted 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 Olmsted County rank for water quality in Minnesota?

Olmsted County ranks #32 out of 87 counties in Minnesota 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

Anoka County

Minnesota

86.0

Water score

Benton County

Minnesota

86.0

Water score

Big Stone County

Minnesota

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.

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 May 14, 2026Reviewed by Evan Brooks, Data Editor

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