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Federal water data

County water report

Clark County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for Clark County, Washington.

Water grade

B

Water score

69.5

State rank

#12

of 39

Health violations

7

EPA SDWIS, 5-year lookback

Watershed impaired

Not reported

EPA ATTAINS coverage varies by state

Monitoring sites

31

29,407 recent measurements

Live streamflow

126%

COLUMBIA RIVER AT VANCOUVER, WA

Water at a glance

Key Water Indicators for Clark County

EPA SDWIS

Safety Grade

B

Score: 69.5 / 100

EPA SDWIS

Active Violations

7

5-year health-based lookback

EPA ATTAINS

Watershed Health

Not reported

Coverage varies by state

USGS NWIS

Streamflow Snapshot

126% of mean

COLUMBIA RIVER AT VANCOUVER, WA

EPA WQP

Monitoring Sites

31

29,407 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

B

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

69.5/100

Health violations

7

Health-based violations

Violations per 100K served

1.2

Population-normalized SDWIS rate

Editorial analysis

Understanding Clark County’s Water

Drinking Water Quality Overview

EPA SDWIS

Clark County earns a B grade for drinking water quality, scoring 69.5 out of 100. Over the past five years, EPA SDWIS records 7 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 2026-05-14T12:00:00.000-07:00) puts COLUMBIA RIVER at 245.0k cfs — flowing above its historical average at 126% 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. Clark County has moderate coverage with 31 active monitoring sites with 29,407 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 Clark County

Water Verdict

Clark County receives a fair water quality assessment with a grade of B and a score of 69.5 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

Clark County has recorded 7 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 1.2 violations per 100,000 people served, this rate is relatively low compared to many U.S. counties.

Consumer Guidance

Tap water in Clark County meets baseline safety standards, though the compliance record shows some violations worth watching. Clark County's drinking-water compliance score is 69.5 out of 100. The violation rate for Clark County is 1.2 per 100,000 people served. Running tap water for 30 seconds before drinking can reduce any localized lead exposure from household plumbing. Requesting your utility's most recent Consumer Confidence Report is the fastest way to identify which specific contaminants were flagged. With 31 active water-quality monitoring sites in Clark County, data coverage is strong. A pipeline streamflow snapshot from the COLUMBIA RIVER gauge is also available on this page.

Regional Context

Clark County has better water quality than the average county in Washington. Its water score is 10.2 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.

Contaminants & Resources

Key issues flagged in Clark County's water environment

Official EPA Resources for Clark County

EPA How's My Waterway

Interactive watershed health data for Clark County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Clark County

Consumer Confidence Reports (WA)

Annual water quality reports from utilities in Washington

Past 5 years

Water Quality Monitoring

Monitoring Sites

31

Active in the past 5 years

Measurements Recorded

29K

29,407 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

245.0Kcfs

May 14, 7:00 PM UTC

vs Long-Term Average

126%

Above typical

Primary Streamgage

COLUMBIA RIVER AT VANCOUVER, WA

USGS site
14144700
Drainage area
241,000 sq mi
Long-term mean
195.2K 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

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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 Clark County:C — Moderate

Some violations or watershed impairment detected.

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 Clark County, Washington?
Clark County, Washington has a drinking-water quality grade of B with a score of 69.5/100, based on EPA SDWIS compliance data. The county has 7 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 Clark County?
Clark County has 7 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 Clark County?
EPA's Water Quality Portal records 29,407 measurements from 31 monitoring sites in Clark 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 Clark County right now?
Clark County's primary USGS streamgage on the COLUMBIA RIVER has a pipeline snapshot of 245,000 cubic feet per second — 126% of the long-term mean of 195,227.27 cfs. Flow is within typical range for this gauge. For the latest gauge feed, visit waterdata.usgs.gov.
How does Clark County water compare to the Washington average?
Clark County's SDWIS water quality score of 69.5/100 is higher than the Washington state average of 59.3. The average water quality grade across Washington is D, based on data from 39 counties with available SDWIS data.
Is tap water safe to drink in Clark County?
Based on EPA SDWIS data, Clark County has a water quality grade of B (69.5/100). 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 Clark County have so many water violations?
Clark County has 7 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 Clark County rank for water quality in Washington?
Clark County ranks #12 out of 39 counties in Washington by SDWIS water quality score (1 = best). With a score of 69.5/100, 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

Chelan County

Washington

B

68.0

Water score

King County

Washington

A

71.1

Water score

Kitsap County

Washington

B

67.5

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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