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Federal water data

County water report

San Juan County Water Report

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

Water grade

F

Water score

4.1

State rank

#37

of 39

Health violations

145

EPA SDWIS, 5-year lookback

Watershed impaired

Not reported

EPA ATTAINS coverage varies by state

Monitoring sites

9

45,662 recent measurements

Live streamflow

No gauge

Primary USGS station not mapped

Water at a glance

Key Water Indicators for San Juan County

EPA SDWIS

Safety Grade

F

Score: 4.1 / 100

EPA SDWIS

Active Violations

145

5-year health-based lookback

EPA ATTAINS

Watershed Health

Not reported

Coverage varies by state

USGS NWIS

Streamflow Snapshot

No gauge

Primary USGS gauge not mapped

EPA WQP

Monitoring Sites

9

45,662 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

F

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

4.1/100

Health violations

145

Health-based violations

Violations per 100K served

978.7

Population-normalized SDWIS rate

Editorial analysis

Understanding San Juan County’s Water

Drinking Water Quality Overview

EPA SDWIS

San Juan County's water systems carry a failing grade, scoring 4.1 out of 100. Over the past five years, EPA SDWIS records 145 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. San Juan County has limited coverage with 9 active monitoring sites with 45,662 recent measurements on record. Predominant monitoring categories include physical and not assigned. 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 San Juan County

Water Verdict

San Juan County receives a poor water quality assessment with a grade of F and a score of 4.1 out of 100. The water supply has documented quality issues. Residents are strongly encouraged to use filtered or bottled water for drinking and to stay informed about utility improvement plans.

Violation Context

San Juan County has recorded 145 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 978.7 violations per 100,000 people served, this rate is high and signals significant water quality management issues.

Consumer Guidance

San Juan County has a Grade F compliance record with 145 health-based violations — among the highest levels in the country. San Juan County's drinking-water compliance score is 4.1 out of 100. Residents are strongly advised to use a certified NSF 58 reverse-osmosis filter or bottled water for all drinking and cooking until violations are corrected. Contacting the Washington Department of Environmental Quality or Health can expedite utility compliance action. There are 9 active water-quality monitoring sites in San Juan County.

Regional Context

San Juan County has poorer water quality than the average county in Washington. Its water score is 55.2 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 San Juan County's water environment

Official EPA Resources for San Juan County

EPA How's My Waterway

Interactive watershed health data for San Juan County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for San Juan County

Consumer Confidence Reports (WA)

Annual water quality reports from utilities in Washington

Past 5 years

Water Quality Monitoring

Monitoring Sites

9

Active in the past 5 years

Measurements Recorded

46K

45,662 total readings

Most Measured

  • Physical
  • Not Assigned
  • 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

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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 San Juan County:F — Failing

High violation count or severe watershed conditions.

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 San Juan County, Washington?
San Juan County, Washington has a drinking-water quality grade of F with a score of 4.1/100, based on EPA SDWIS compliance data. The county has 145 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 San Juan County?
San Juan County has 145 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 San Juan County?
EPA's Water Quality Portal records 45,662 measurements from 9 monitoring sites in San Juan County over the past five years. The most frequently measured characteristic groups are Physical, Not Assigned, 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 San Juan County water compare to the Washington average?
San Juan County's SDWIS water quality score of 4.1/100 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 San Juan County?
Based on EPA SDWIS data, San Juan County has a water quality grade of F (4.1/100). 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 San Juan County have so many water violations?
San Juan County has 145 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 San Juan County rank for water quality in Washington?
San Juan County ranks #37 out of 39 counties in Washington by SDWIS water quality score (1 = best). With a score of 4.1/100, 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

Garfield County

Washington

F

3.6

Water score

Ferry County

Washington

F

2.0

Water score

Island County

Washington

F

8.2

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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