Alaska Water Quality
Drinking water data for all 19 counties.
Avg SDWIS Compliance Index
14.0
Most Common Five-Year SDWIS Compliance Band
F
Counties with Data
19
of 19 total
County water atlas
Alaska water signals by county
A state-level 2.5D view across drinking-water compliance, watershed impairment, monitoring density, and streamflow snapshot context. Pin any county, switch layers, then use the lens controls to compare index ranges, recorded violation rates, or impaired watersheds without leaving the page.
Counties
19
Avg SDWIS index
14.0
Watersheds
7
ATTAINS counties
Monitoring
17
15 fresh USGS snapshots
State atlas layers combine EPA SDWIS health-based violations, EPA ATTAINS 303(d) impairment assessments, EPA Water Quality Portal monitoring sites, and representative USGS NWIS streamflow gauges. Streamflow values appear only for fresh pipeline snapshots, not as a continuously updated stream. County pages include the observation time and year.
Multi-source coverage in Alaska
Beyond Drinking Water
EPA SDWIS
19/ 19
counties with drinking-water compliance data
777 health violations statewide (5yr)
EPA ATTAINS
49.0%
avg impaired across 7 counties
16 of 22 assessed bodies impaired
EPA WQP
553
monitoring sites across 17 counties
116,399 total readings (5yr window)
USGS NWIS
15
counties with a fresh pipeline snapshot
11 above3 below
State atlas notes
What stands out in Alaska
County water quality is not one number. The strongest read comes from comparing drinking-water compliance against watershed impairment, monitoring density, and streamflow context. Use these signals as a starting point, then open any county profile for source-level detail.
Compliance spread
Anchorage Municipality has the highest value in the published state SDWIS Compliance Index table at 54.7/100, while Yukon-Koyukuk Census Area has the lowest at 0.3/100. That is a 54.4 point gap inside one state.
Zero health violations
0
3+ health violations
16
Watershed pressure
The atlas impairment layer points to counties where assessed water bodies are most likely to miss state quality standards. Assessment density varies, so compare the percentage with the number of assessed bodies on the county page.
Monitoring hubs
Highest fresh streamflow pipeline snapshots: Bethel Census Area (295%, observation 2026), Nome Census Area (273%, observation 2026), Kenai Peninsula Borough (237%, observation 2026). These are source-data observations, not household tap-water conclusions.
Highest SDWIS Compliance Index Values
#1
Anchorage Municipality
54.7
Band C, 19 recorded health-based violations
#2
North Slope Borough
47.1
Band C, 1 recorded health-based violations
#3
Fairbanks North Star Borough
42.0
Band D, 26 recorded health-based violations
#4
Sitka City and Borough
37.6
Band D, 2 recorded health-based violations
#5
Aleutians West Census Area
16.4
Band F, 8 recorded health-based violations
Lowest SDWIS Compliance Index Values
#1
Yukon-Koyukuk Census Area
0.3
Band F, 120 recorded health-based violations
#2
Northwest Arctic Borough
0.4
Band F, 149 recorded health-based violations
#3
Lake and Peninsula Borough
0.4
Band F, 36 recorded health-based violations
#4
Bethel Census Area
1.2
Band F, 147 recorded health-based violations
#5
Nome Census Area
1.6
Band F, 82 recorded health-based violations
All Alaska Counties
Frequently Asked Questions
Which Alaska county has the highest SDWIS Compliance Index?
What does the Five-Year SDWIS Compliance Band mean?
What does EPA ATTAINS report across Alaska?
Which USGS streamflow records are shown across Alaska?
Where can Alaska residents find current official information?
What does Water Quality Portal monitoring volume show in Alaska?
Data Sources
Drinking-water compliance data from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. The WaterByCounty SDWIS Compliance Index reflects the recorded rate and is not an EPA score.
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.