County water report

Snohomish County Water Report

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

Water grade

Water score

86.0

State rank

of 39

Health violations

EPA SDWIS, 5-year lookback

Watershed impaired

Not reported

EPA ATTAINS coverage varies by state

Monitoring sites

197

27,068 recent measurements

Live streamflow

No gauge

SNOHOMISH RIVER AT SNOHOMISH, WA

Water at a glance

Key Water Indicators for Snohomish 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

No gauge

SNOHOMISH RIVER AT SNOHOMISH, WA

EPA WQP

Monitoring Sites

197

27,068 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

Snohomish County has 4 facilities in the DCWSI dataset.

ByCounty's DCWSI ranks this county #37 nationally by combining its water score with mapped data center density.

DCWSI

78.7

0-100 index

Facility count

67.8 density percentile

Discharge estimate

Not reported

EPA CWA fields where available

Water vs median

+36.0

Compared with US county median

Named operators

CentersquareUnity Cable System

Mapped facilities

ATANDT LYNNWOOD
LYNNWOOD
EPA ECHO
Centersquare Lynnwood SE1
Lynnwood · Centersquare
OSM
Digital Fortress Lynnwood
Facility details limited
OSM
Norma Beach Cable Landing Station
Lynnwood · Unity Cable System
OSM

See the Snohomish County data-center report Review methodology

Data Center Water Budget Calculator

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

Facility size: 100 MW

1 MW1,000 MW

Cooling type

Utilization: 70%

40%100%

799K gallons/dayHigh Impact

Your facility would use 52.1% of this county's industrial water baseline. Verify water rights and long-term drought projections before committing.

52.1% of county industrial baseline0.73 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 Snohomish County’s Water

Drinking Water Quality Overview

EPA SDWIS

Snohomish 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.

Monitoring Network

EPA WQP

EPA's Water Quality Portal (WQP) aggregates monitoring data from federal, state, and tribal agencies. Snohomish County has extensive coverage with 197 active monitoring sites with 27,068 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 Snohomish County

Water Verdict

Snohomish County, Washington 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 1,714 square miles of upstream watershed, giving local source waters a regional footprint.

Violation Context

EPA SDWIS records for Snohomish County, Washington 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: 27,068 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 Snohomish County shows no recent health-based violations. No health-based violations have been recorded, placing Snohomish County in the top tier for drinking-water safety. Snohomish 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 197 active water-quality monitoring sites in Snohomish County, data coverage is strong. A pipeline streamflow snapshot from the SNOHOMISH RIVER gauge is also available on this page.

Regional Context

Snohomish County has better water quality than the average county in Washington. Its water score is 26.7 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

197

Active in the past 5 years

Measurements Recorded

27K

27,068 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).

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 Snohomish 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 →

Snohomish 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 Snohomish County, Washington?

Snohomish County, Washington 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 Snohomish County?

Snohomish 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 Snohomish County?

EPA's Water Quality Portal records 27,068 measurements from 197 monitoring sites in Snohomish 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 Snohomish County water compare to the Washington average?

Snohomish County's SDWIS water quality score of 86.0/100 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 Snohomish County?

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

Snohomish 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 Snohomish County rank for water quality in Washington?

Snohomish County ranks #8 out of 39 counties in Washington by SDWIS water quality score (1 = best). With a score of 86.0/100, 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

Asotin County

Washington

86.0

Water score

Columbia County

Washington

86.0

Water score

Douglas County

Washington

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.

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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