waterbycounty
EPA SDWIS

Multnomah County Water Quality

Multnomah County, Oregon

Water Grade

B

Water Score

66.8

Violations

21

State Rank

#9

of 36 (1 = best)

EPA SDWIS Compliance

Drinking Water Quality

Water Quality Grade

B

Based on EPA compliance history and violation data

Water Score

66.8/100

Higher = better quality

Health Violations

21

Health-based violations

Violation Rate

2.5%

Systems with violations

Water Advisory: Multnomah County

Water Verdict

Multnomah County receives a fair water quality assessment with a grade of B and a score of 66.8 out of 100. The water supply meets baseline federal standards, but there may be periods of elevated contaminant levels or infrastructure concerns worth monitoring.

Violation Context

Multnomah County has recorded 21 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 2.5 violations per 1,000 residents, this rate is relatively low compared to many U.S. counties.

Consumer Guidance

Tap water in Multnomah 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 21 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

Multnomah County has better water quality than the average county in Oregon. Its water score is 22.2 points higher than the state average, indicating stronger water system performance relative to neighboring counties.

Past 5 years

Water Quality Monitoring

Monitoring Sites

107

Active in the past 5 years

Measurements Recorded

29K

28,680 total readings

Most Measured

  • Organics, Pesticide
  • Physical
  • 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

17.5Kcfs

May 14, 6:45 PM UTC

vs Long-Term Average

54%

Well below typical

Primary Streamgage

WILLAMETTE RIVER AT PORTLAND, OR

USGS site
14211720
Drainage area
11,200 sq mi
Long-term mean
32.5K 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 Multnomah County, Oregon?
Multnomah County, Oregon has a drinking-water quality grade of B with a score of 66.8/100, based on EPA SDWIS compliance data. The county has 21 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 Multnomah County?
Multnomah County has 21 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 Multnomah County?
EPA's Water Quality Portal records 28,680 measurements from 107 monitoring sites in Multnomah County over the past five years. The most frequently measured characteristic groups are Organics, Pesticide, Physical, 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 Multnomah County right now?
Multnomah County's primary USGS streamgage on the WILLAMETTE RIVER is currently reading 17,500 cubic feet per second — 54% of the long-term mean of 32,501.13 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 Multnomah County water compare to the Oregon average?
Multnomah County's SDWIS water quality score of 66.8/100 is higher than the Oregon state average of 44.6. The average water quality grade across Oregon is D, based on data from 36 counties with available SDWIS data.
Is tap water safe to drink in Multnomah County?
Based on EPA SDWIS data, Multnomah County has a water quality grade of B (66.8/100). 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).
Why does Multnomah County have so many water violations?
Multnomah County has 21 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 Multnomah County rank for water quality in Oregon?
Multnomah County ranks #9 out of 36 counties in Oregon by SDWIS water quality score (1 = best). With a score of 66.8/100, it falls in the top 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

Washington County

Oregon

B

67.7

Water score

Deschutes County

Oregon

C

60.1

Water score

Linn County

Oregon

C

53.8

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

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