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EPA SDWIS

Caribou County Water Quality

Caribou County, Idaho

Water Grade

F

Water Score

36.7

Violations

2

State Rank

#16

of 44 (1 = best)

EPA SDWIS Compliance

Drinking Water Quality

Water Quality Grade

F

Based on EPA compliance history and violation data

Water Score

36.7/100

Higher = better quality

Health Violations

2

Health-based violations

Violation Rate

41.5%

Systems with violations

Water Advisory: Caribou County

Water Verdict

Caribou County receives a poor water quality assessment with a grade of F and a score of 36.7 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

Caribou County has recorded 2 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 41.5 violations per 1,000 residents, this rate is high and signals significant water quality management issues.

Consumer Guidance

Residents of Caribou County are advised to use filtered or bottled water for drinking and cooking until water quality improves. A reverse-osmosis or activated-carbon filter certified to remove the contaminants listed in the utility's Consumer Confidence Report is recommended. With 2 recorded health violations, staying informed about utility communications and boil-water notices is especially important. For long-term peace of mind, request your utility's latest Consumer Confidence Report and consider independent water testing if you have specific health concerns.

Regional Context

Caribou County has water quality close to the average county in Idaho. Its water score is within 4.1 points of the state average, meaning its overall water system performance is broadly representative of Idaho as a whole.

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

56.3%

358 of 636 assessed

Moderate concern

Top Impairment Causes

  • 1

    SEDIMENTATION/SILTATION

  • 2

    PHOSPHORUS, TOTAL

  • 3

    ESCHERICHIA COLI (E. COLI)

Source: EPA ATTAINS · Reporting cycle 2022

Impairment is determined under the Clean Water Act §303(d): a water body is impaired when it fails to meet state-defined quality standards for designated uses (drinking, recreation, aquatic life). Assessment coverage varies by state — counties without assessed water bodies are not shown.

Past 5 years

Water Quality Monitoring

Monitoring Sites

171

Active in the past 5 years

Measurements Recorded

11K

10,554 total readings

Most Measured

  • Physical
  • Biological, Counts
  • Biological, Fish

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).

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Frequently Asked Questions

What is the water quality in Caribou County, Idaho?
Caribou County, Idaho has a drinking-water quality grade of F with a score of 36.7/100, based on EPA SDWIS compliance data. The county has 2 health-based drinking water violations over the past 5 years. Watershed health, monitoring records, and live streamflow are reported separately on this page.
Are there any water violations in Caribou County?
Caribou County has 2 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 healthy are the watersheds in Caribou County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 56.3% of Caribou County's 636 assessed water bodies are classified as impaired (358 impaired). The top reported causes are SEDIMENTATION/SILTATION, PHOSPHORUS, TOTAL, ESCHERICHIA COLI (E. COLI). Impairment means the water body fails to meet state quality standards for at least one designated use — drinking water source, recreation, aquatic life, or fish consumption. Note: watershed impairment doesn't always translate to tap-water issues; treatment plants can remove most regulated contaminants.
How much water-quality monitoring happens in Caribou County?
EPA's Water Quality Portal records 10,554 measurements from 171 monitoring sites in Caribou County over the past five years. The most frequently measured characteristic groups are Physical, Biological, Counts, Biological, Fish. 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 Caribou County water compare to the Idaho average?
Caribou County's SDWIS water quality score of 36.7/100 is higher than the Idaho state average of 32.6. The average water quality grade across Idaho is F, based on data from 44 counties with available SDWIS data.
Is tap water safe to drink in Caribou County?
Based on EPA SDWIS data, Caribou County has a water quality grade of F (36.7/100). 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).
Does Caribou County have clean drinking water?
Caribou County has 2 health-based drinking water violations according to EPA records. With a water quality score of 36.7/100 and grade F, the county's drinking water has had some compliance issues but continues to be monitored. 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 Caribou County rank for water quality in Idaho?
Caribou County ranks #16 out of 44 counties in Idaho by SDWIS water quality score (1 = best). With a score of 36.7/100, it falls in the middle 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

Lincoln County

Idaho

F

35.8

Water score

Teton County

Idaho

F

35.7

Water score

Kootenai County

Idaho

F

35.5

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.

Watershed health and impaired-waterway data from the EPA ATTAINS Clean Water Act §303(d) assessments — state-reported, EPA-finalized.

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 Logan Johnson, Founder & Data EditorUpdated Reviewed by Logan Johnson, Founder & Data Editor

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