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County water report

Kauai County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for Kauai County, Hawaii.

Water grade

A

Water score

86.0

State rank

#1

of 4

Health violations

0

EPA SDWIS, 5-year lookback

Watershed impaired

Not reported

EPA ATTAINS coverage varies by state

Monitoring sites

38

8,514 recent measurements

Live streamflow

142%

Waimea River near Waimea, Kauai, HI

Water at a glance

Key Water Indicators for Kauai County

EPA SDWIS

Safety Grade

A

Score: 86.0 / 100

EPA SDWIS

Active Violations

0

5-year health-based lookback

EPA ATTAINS

Watershed Health

Not reported

Coverage varies by state

USGS NWIS

Streamflow Snapshot

142% of mean

Waimea River near Waimea, Kauai, HI

EPA WQP

Monitoring Sites

38

8,514 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

A

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

86.0/100

Health violations

0

Health-based violations

Violations per 100K served

0.0

Population-normalized SDWIS rate

Editorial analysis

Understanding Kauai County’s Water

Drinking Water Quality Overview

EPA SDWIS

Kauai 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 mid-sized county.

River & Streamflow Status

USGS NWIS

USGS NWIS gauge data (as of 2026-05-14T08:30:00.000-10:00) puts Waimea River at 182.0 cfs — flowing above its historical average at 142% 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. Kauai County has moderate coverage with 38 active monitoring sites with 8,514 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 Kauai County

Water Verdict

Kauai County 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.

Violation Context

Kauai County has recorded zero health-based violations, indicating no recent health-based violations in the reporting period. The violation rate is zero per 100,000 people served, which is the best possible outcome.

Consumer Guidance

The EPA compliance record for Kauai County shows no recent health-based violations. No health-based violations have been recorded, placing Kauai County in the top tier for drinking-water safety. Kauai 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 38 active water-quality monitoring sites in Kauai County, data coverage is strong. A pipeline streamflow snapshot from the Waimea River gauge is also available on this page.

Regional Context

Kauai County has better water quality than the average county in Hawaii. Its water score is 7.4 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

38

Active in the past 5 years

Measurements Recorded

8.5K

8,514 total readings

Most Measured

  • Physical
  • Microbiological
  • 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

182cfs

May 14, 6:30 PM UTC

vs Long-Term Average

142%

Well above typical

Primary Streamgage

Waimea River near Waimea, Kauai, HI

USGS site
16031000
Drainage area
57.63 sq mi
Long-term mean
128 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.

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Estimate Your Water Costs

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 Kauai 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.

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Kauai 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 Kauai County, Hawaii?
Kauai County, Hawaii 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 Kauai County?
Kauai 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 Kauai County?
EPA's Water Quality Portal records 8,514 measurements from 38 monitoring sites in Kauai County over the past five years. The most frequently measured characteristic groups are Physical, Microbiological, 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 Kauai County right now?
Kauai County's primary USGS streamgage on the Waimea River has a pipeline snapshot of 182 cubic feet per second — 142% of the long-term mean of 128.29 cfs. This is well above typical — often a signal of recent precipitation or storm runoff. For the latest gauge feed, visit waterdata.usgs.gov.
How does Kauai County water compare to the Hawaii average?
Kauai County's SDWIS water quality score of 86.0/100 is higher than the Hawaii state average of 78.6. The average water quality grade across Hawaii is B, based on data from 4 counties with available SDWIS data.
Is tap water safe to drink in Kauai County?
Based on EPA SDWIS data, Kauai 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 Kauai County have clean drinking water?
Kauai 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 Kauai County rank for water quality in Hawaii?
Kauai County ranks #1 out of 4 counties in Hawaii 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

Maui County

Hawaii

A

86.0

Water score

Honolulu County

Hawaii

A

71.9

Water score

Hawaii County

Hawaii

A

70.6

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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