waterbycounty
Compiled federal source snapshot

Oregon Water Quality

Drinking water data for all 36 counties.

Avg SDWIS Compliance Index

42.4

Most Common Five-Year SDWIS Compliance Band

D

Counties with Data

36

of 36 total

County water atlas

Oregon water signals by county

A state-level 2.5D view across drinking-water compliance, watershed impairment, monitoring density, and streamflow snapshot context. Pin any county, switch layers, then use the lens controls to compare index ranges, recorded violation rates, or impaired watersheds without leaving the page.

Counties

36

Avg SDWIS index

42.4

Watersheds

0

ATTAINS counties

Monitoring

36

25 fresh USGS snapshots

State atlas layers combine EPA SDWIS health-based violations, EPA ATTAINS 303(d) impairment assessments, EPA Water Quality Portal monitoring sites, and representative USGS NWIS streamflow gauges. Streamflow values appear only for fresh pipeline snapshots, not as a continuously updated stream. County pages include the observation time and year.

Prepared by ByCounty Editorial TeamPublished by WaterByCounty

Multi-source coverage in Oregon

Beyond Drinking Water

EPA SDWIS

36/ 36

counties with drinking-water compliance data

622 health violations statewide (5yr)

EPA ATTAINS

—

No §303(d) assessments yet for Oregon

EPA WQP

3,790

monitoring sites across 36 counties

2,940,615 total readings (5yr window)

USGS NWIS

25

counties with a fresh pipeline snapshot

0 above25 below

State atlas notes

What stands out in Oregon

County water quality is not one number. The strongest read comes from comparing drinking-water compliance against watershed impairment, monitoring density, and streamflow context. Use these signals as a starting point, then open any county profile for source-level detail.

Compliance spread

Gilliam County has the highest value in the published state SDWIS Compliance Index table at 86.2/100, while Malheur County has the lowest at 8.5/100. That is a 77.7 point gap inside one state.

Zero health violations

5

3+ health violations

26

Monitoring hubs

Umatilla County404 sitesDouglas County292 sitesJackson County273 sites

Lowest flow reads

Coos County1%Wheeler County1%Grant County2%

Highest fresh streamflow pipeline snapshots: Jefferson County (77%, observation 2026), Sherman County (66%, observation 2026), Lane County (58%, observation 2026). These are source-data observations, not household tap-water conclusions.

All Oregon Counties

CountySDWIS Compliance Index
Gilliam County86.2
Jefferson County86.2
Union County86.2
Wallowa County86.2
Wheeler County86.2
Multnomah County69.8
Washington County67.8
Deschutes County60.1
Polk County52.7
Marion County51.2
Hood River County51.1
Linn County49.9
Umatilla County49.9
Klamath County42.4
Clackamas County39.6
Yamhill County38.7
Crook County38.4
Harney County36.8
Benton County36.2
Baker County35.0
Clatsop County34.8
Douglas County34.1
Lake County33.4
Tillamook County32.7
Lane County32.1
Morrow County31.9
Lincoln County31.5
Grant County23.9
Jackson County23.7
Josephine County19.0
Sherman County16.1
Wasco County13.9
Curry County13.8
Coos County13.4
Columbia County12.2
Malheur County8.5

Frequently Asked Questions

Which Oregon county has the highest SDWIS Compliance Index?
Gilliam County has the highest SDWIS Compliance Index in the published Oregon cohort at 86.2/100. This WaterByCounty relative comparison is not an EPA score and does not establish current conditions for a utility or address.
What does the Five-Year SDWIS Compliance Band mean?
The band is derived only from each county aggregation's recorded health-violation rate per 100,000 people served for the stated five-year source window. It is separate from the relative SDWIS Compliance Index and is not a current determination for a specific utility or address.
Which USGS streamflow records are shown across Oregon?
WaterByCounty has 25 fresh USGS pipeline snapshots in the published Oregon cohort. Each county page shows its observation timestamp and year. A pipeline snapshot is not a continuously updated reading or a tap-water safety measure.
Where can Oregon residents find current official information?
Review the applicable utility's Consumer Confidence Report, active notices, and the state drinking-water agency. WaterByCounty's county-level historical aggregations do not establish the current status of a specific utility, address, private well, or household plumbing system.
What does Water Quality Portal monitoring volume show in Oregon?
The published county records contain 2,940,615 results from 3,790 monitoring locations in the site's five-year aggregation. Monitoring volume does not by itself indicate better or worse water quality.

Data Sources

Drinking-water compliance data from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. The WaterByCounty SDWIS Compliance Index reflects the recorded rate and is not an EPA score.

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.

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