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Federal water data

County water report

Lewis County Water Report

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

Water grade

D

Water score

49.9

State rank

#30

of 39

Health violations

11

EPA SDWIS, 5-year lookback

Watershed impaired

Not reported

EPA ATTAINS coverage varies by state

Monitoring sites

28

10,091 recent measurements

Live streamflow

No gauge

COWLITZ RIVER AT TOLEDO, WA

Water at a glance

Key Water Indicators for Lewis County

EPA SDWIS

Safety Grade

D

Score: 49.9 / 100

EPA SDWIS

Active Violations

11

5-year health-based lookback

EPA ATTAINS

Watershed Health

Not reported

Coverage varies by state

USGS NWIS

Streamflow Snapshot

No gauge

COWLITZ RIVER AT TOLEDO, WA

EPA WQP

Monitoring Sites

28

10,091 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

D

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

49.9/100

Health violations

11

Health-based violations

Violations per 100K served

16.8

Population-normalized SDWIS rate

Editorial analysis

Understanding Lewis County’s Water

Drinking Water Quality Overview

EPA SDWIS

Lewis County's drinking water received a D grade, scoring 49.9 out of 100. Over the past five years, EPA SDWIS records 11 health-based violations — a pattern that public water utilities are required to disclose and correct.

Monitoring Network

EPA WQP

EPA's Water Quality Portal (WQP) aggregates monitoring data from federal, state, and tribal agencies. Lewis County has moderate coverage with 28 active monitoring sites with 10,091 recent measurements on record. Predominant monitoring categories include physical and microbiological. 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 Lewis County

Water Verdict

Lewis County receives a below-average water quality assessment with a grade of D and a score of 49.9 out of 100. Residents should review their utility's Consumer Confidence Report and may want to consider additional water filtration for drinking.

Violation Context

Lewis County has recorded 11 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 16.8 violations per 100,000 people served, this rate is high and signals significant water quality management issues.

Consumer Guidance

Lewis County's drinking-water compliance is below average with a Grade D, indicating repeated or unresolved violations in the recent record. Lewis County's drinking-water compliance score is 49.9 out of 100. The violation rate for Lewis County is 16.8 per 100,000 people served. Residents are encouraged to use an NSF 53 or NSF 58-certified filter for drinking and cooking water until the underlying violations are resolved. Running tap water for 30 seconds before use and avoiding older lead-pipe connections can also reduce exposure risk. The current Consumer Confidence Report from your utility will specify the contaminants of concern. With 28 active water-quality monitoring sites in Lewis County, data coverage is strong. A pipeline streamflow snapshot from the COWLITZ RIVER gauge is also available on this page.

Regional Context

Lewis County has poorer water quality than the average county in Washington. Its water score is 9.4 points lower than the state average, suggesting more challenges with contamination control or infrastructure than 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 Lewis County's water environment

Official EPA Resources for Lewis County

EPA How's My Waterway

Interactive watershed health data for Lewis County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Lewis County

Consumer Confidence Reports (WA)

Annual water quality reports from utilities in Washington

Past 5 years

Water Quality Monitoring

Monitoring Sites

28

Active in the past 5 years

Measurements Recorded

10K

10,091 total readings

Most Measured

  • Physical
  • Microbiological
  • 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).

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Annual Total

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Monthly

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Water Bill

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Filter Cost

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Safety Grade for Lewis County:D — Poor

Elevated violations or significant watershed impairment.

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 Lewis County, Washington?
Lewis County, Washington has a drinking-water quality grade of D with a score of 49.9/100, based on EPA SDWIS compliance data. The county has 11 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 Lewis County?
Lewis County has 11 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 Lewis County?
EPA's Water Quality Portal records 10,091 measurements from 28 monitoring sites in Lewis County over the past five years. The most frequently measured characteristic groups are Physical, Microbiological, 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.
How does Lewis County water compare to the Washington average?
Lewis County's SDWIS water quality score of 49.9/100 is lower 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 Lewis County?
Based on EPA SDWIS data, Lewis County has a water quality grade of D (49.9/100). This indicates below-average compliance with significant violations. Residents may want to consider home water filtration or independent testing. 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 Lewis County have so many water violations?
Lewis County has 11 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 Lewis County rank for water quality in Washington?
Lewis County ranks #30 out of 39 counties in Washington by SDWIS water quality score (1 = best). With a score of 49.9/100, it falls in the bottom 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

Okanogan County

Washington

D

49.7

Water score

Thurston County

Washington

C

50.8

Water score

Walla Walla County

Washington

C

53.3

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.

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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