waterbycounty
Compiled federal source snapshot

Colorado Water Quality

Drinking water data for all 64 counties.

Avg SDWIS Compliance Index

37.7

Most Common Five-Year SDWIS Compliance Band

F

Counties with Data

64

of 64 total

County water atlas

Colorado 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

64

Avg SDWIS index

37.7

Watersheds

64

ATTAINS counties

Monitoring

64

39 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.

Prepared by ByCounty Editorial TeamPublished by WaterByCounty

Multi-source coverage in Colorado

Beyond Drinking Water

EPA SDWIS

64/ 64

counties with drinking-water compliance data

1,350 health violations statewide (5yr)

EPA ATTAINS

54.2%

avg impaired across 64 counties

3,398 of 6,496 assessed bodies impaired

EPA WQP

3,274

monitoring sites across 64 counties

1,316,109 total readings (5yr window)

USGS NWIS

39

counties with a fresh pipeline snapshot

1 above36 below

State atlas notes

What stands out in Colorado

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

Cheyenne County has the highest value in the published state SDWIS Compliance Index table at 86.2/100, while Otero County has the lowest at 0.3/100. That is a 85.9 point gap inside one state.

Zero health violations

7

3+ health violations

41

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.

Cheyenne County100.0%Prowers County100.0%Kiowa County90.9%

Monitoring hubs

San Juan County230 sitesEl Paso County210 sitesLa Plata County173 sites

Lowest flow reads

Teller County0%Las Animas County1%Archuleta County3%

Highest fresh streamflow pipeline snapshots: Boulder County (117%, observation 2026), Grand County (93%, observation 2026), Douglas County (91%, observation 2026). These are source-data observations, not household tap-water conclusions.

All Colorado Counties

CountySDWIS Compliance Index
Cheyenne County86.2
Crowley County86.2
Custer County86.2
Gilpin County86.2
Jackson County86.2
Mineral County86.2
San Juan County86.2
Denver County72.3
Arapahoe County70.7
Mesa County70.7
Broomfield County69.3
Adams County61.6
Jefferson County61.0
Weld County60.7
Douglas County58.0
Boulder County57.3
Summit County56.7
Grand County54.5
Eagle County54.3
Las Animas County53.8
Pitkin County53.3
El Paso County53.0
Moffat County49.3
Lake County47.7
Fremont County47.4
Larimer County47.4
Yuma County43.6
Montezuma County40.7
Chaffee County39.0
Archuleta County36.6
Elbert County35.4
Lincoln County34.3
Kit Carson County33.7
Saguache County29.6
Logan County28.9
Pueblo County27.2
Gunnison County27.0
Rio Blanco County26.5
Montrose County25.4
Morgan County24.5
La Plata County22.1
Routt County21.9
Garfield County21.5
Phillips County21.2
Conejos County18.8
Washington County18.7
Clear Creek County13.6
Alamosa County13.2
Delta County12.4
San Miguel County12.4
Sedgwick County11.9
Costilla County11.0
Hinsdale County9.4
Ouray County9.3
Rio Grande County8.4
Park County6.8
Teller County6.7
Huerfano County5.5
Dolores County3.4
Bent County3.1
Kiowa County2.5
Baca County0.9
Prowers County0.5
Otero County0.3

Frequently Asked Questions

Which Colorado county has the highest SDWIS Compliance Index?
Cheyenne County has the highest SDWIS Compliance Index in the published Colorado cohort at 86.2/100. This WaterByCounty relative comparison is not an EPA score and does not establish current conditions for a utility or address.
What does the Five-Year SDWIS Compliance Band mean?
The band is derived only from each county aggregation's recorded health-violation rate per 100,000 people served for the stated five-year source window. It is separate from the relative SDWIS Compliance Index and is not a current determination for a specific utility or address.
What does EPA ATTAINS report across Colorado?
Across 64 published Colorado county records with EPA ATTAINS data, 3,398 of 6,496 assessed water bodies are listed as impaired. This is a watershed assessment and does not describe finished household tap water.
Which USGS streamflow records are shown across Colorado?
WaterByCounty has 39 fresh USGS pipeline snapshots in the published Colorado cohort. Each county page shows its observation timestamp and year. A pipeline snapshot is not a continuously updated reading or a tap-water safety measure.
Where can Colorado residents find current official information?
Review the applicable utility's Consumer Confidence Report, active notices, and the state drinking-water agency. WaterByCounty's county-level historical aggregations do not establish the current status of a specific utility, address, private well, or household plumbing system.
What does Water Quality Portal monitoring volume show in Colorado?
The published county records contain 1,316,109 results from 3,274 monitoring locations in the site's five-year aggregation. Monitoring volume does not by itself indicate better or worse water quality.

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.

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