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County water report

Bonneville County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for Bonneville County, Idaho.

Water grade

D

Water score

44.7

State rank

#14

of 44

Health violations

29

EPA SDWIS, 5-year lookback

Watershed impaired

49.8%

422 water bodies assessed

Monitoring sites

43

6,749 recent measurements

Live streamflow

89%

SNAKE RIVER AB EAGLE ROCK NR IDAHO FALLS ID

Water at a glance

Key Water Indicators for Bonneville County

EPA SDWIS

Safety Grade

D

Score: 44.7 / 100

EPA SDWIS

Active Violations

29

5-year health-based lookback

EPA ATTAINS

Watershed Health

50% impaired

422 bodies assessed

USGS NWIS

Streamflow Snapshot

89% of mean

SNAKE RIVER AB EAGLE ROCK NR IDAHO FALLS ID

EPA WQP

Monitoring Sites

43

6,749 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

D

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

44.7/100

Health violations

29

Health-based violations

Violations per 100K served

24.4

Population-normalized SDWIS rate

Editorial analysis

Understanding Bonneville County’s Water

Drinking Water Quality Overview

EPA SDWIS

Bonneville County's drinking water received a D grade, scoring 44.7 out of 100. Over the past five years, EPA SDWIS records 29 health-based violations — a pattern that public water utilities are required to disclose and correct.

Watershed Conditions

EPA ATTAINS

Under the Clean Water Act §303(d), EPA ATTAINS tracks whether waterways meet quality standards for drinking, recreation, and aquatic life (reporting cycle: 2022). A substantial 49.8% of assessed waterways are impaired (210 of 422 water bodies) across Bonneville County's watersheds. The leading impairment causes are sedimentation/siltation and temperature. Impairment does not mean tap water is unsafe — it measures ambient waterway conditions upstream of treatment, not finished drinking water.

River & Streamflow Status

USGS NWIS

USGS NWIS gauge data (as of 2026-05-14T12:15:00.000-06:00) puts SNAKE RIVER AB EAGLE ROCK at 5.3k cfs — running somewhat below its historical average at 89% 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. Bonneville County has moderate coverage with 43 active monitoring sites with 6,749 recent measurements on record. Predominant monitoring categories include physical and biological, counts. 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 Bonneville County

Water Verdict

Bonneville County, Idaho receives a below-average water quality assessment with a grade of D and a score of 44.7 out of 100. Residents should review their utility's Consumer Confidence Report and may want to consider additional water filtration for drinking. Separately, EPA ATTAINS assessments cover 422 water bodies in the county's watershed, with 49.8% listed as impaired under the Clean Water Act — a source-water measure that is tracked independently of tap-water compliance. At the most recent USGS reading, local streamflow was below its historical mean at 89.4% — worth watching in drier seasons.

Violation Context

EPA SDWIS records for Bonneville County, Idaho show 29 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 24.4 violations per 100,000 people served, this rate is high and signals significant water quality management issues. For independent context, 6,749 water-quality monitoring results have been recorded across the county in the EPA Water Quality Portal over the past five years.

Consumer Guidance

Bonneville County's drinking-water compliance is below average with a Grade D, indicating repeated or unresolved violations in the recent record. Bonneville County's drinking-water compliance score is 44.7 out of 100. The violation rate for Bonneville County is 24.4 per 100,000 people served. Residents are encouraged to use an NSF 53 or NSF 58-certified filter for drinking and cooking water until the underlying violations are resolved. Running tap water for 30 seconds before use and avoiding older lead-pipe connections can also reduce exposure risk. The current Consumer Confidence Report from your utility will specify the contaminants of concern. Sedimentation/Siltation is the leading impairment cause in Bonneville County's watershed. With 43 active water-quality monitoring sites in Bonneville County, data coverage is strong. A pipeline streamflow snapshot from the SNAKE RIVER AB EAGLE ROCK gauge is also available on this page.

Regional Context

Bonneville County has better water quality than the average county in Idaho. Its water score is 12.1 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.

Contaminants & Resources

Key issues flagged in Bonneville County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    Sedimentation and siltation

    Impairment cause per EPA Clean Water Act §303(d) assessment

  • 2

    Elevated temperature

    Impairment cause per EPA Clean Water Act §303(d) assessment

  • 3

    Physical Substrate Habitat Alterations

    Impairment cause per EPA Clean Water Act §303(d) assessment

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for Bonneville County

EPA How's My Waterway

Interactive watershed health data for Bonneville County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Bonneville County

Consumer Confidence Reports (ID)

Annual water quality reports from utilities in Idaho

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

49.8%

210 of 422 assessed

Moderate concern

Top Impairment Causes

  • 1

    SEDIMENTATION/SILTATION

  • 2

    TEMPERATURE

  • 3

    PHYSICAL SUBSTRATE HABITAT ALTERATIONS

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

43

Active in the past 5 years

Measurements Recorded

6.7K

6,749 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).

Live USGS Streamgage

River & Stream Conditions

Current Discharge

5,270cfs

May 14, 6:15 PM UTC

vs Long-Term Average

89%

Below typical

Primary Streamgage

SNAKE RIVER AB EAGLE ROCK NR IDAHO FALLS ID

USGS site
13057155
Drainage area
9,533 sq mi
Long-term mean
5,897 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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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 Bonneville County:C — Moderate

Some violations or watershed impairment detected.

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 Bonneville County, Idaho?
Bonneville County, Idaho has a drinking-water quality grade of D with a score of 44.7/100, based on EPA SDWIS compliance data. The county has 29 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 Bonneville County?
Bonneville County has 29 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 Bonneville County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 49.8% of Bonneville County's 422 assessed water bodies are classified as impaired (210 impaired). The top reported causes are SEDIMENTATION/SILTATION, TEMPERATURE, PHYSICAL SUBSTRATE HABITAT ALTERATIONS. 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 Bonneville County?
EPA's Water Quality Portal records 6,749 measurements from 43 monitoring sites in Bonneville 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.
What's happening with rivers in Bonneville County right now?
Bonneville County's primary USGS streamgage on the SNAKE RIVER AB EAGLE ROCK has a pipeline snapshot of 5,270 cubic feet per second — 89% of the long-term mean of 5,897.46 cfs. Flow is within typical range for this gauge. For the latest gauge feed, visit waterdata.usgs.gov.
How does Bonneville County water compare to the Idaho average?
Bonneville County's SDWIS water quality score of 44.7/100 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 Bonneville County?
Based on EPA SDWIS data, Bonneville County has a water quality grade of D (44.7/100). 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).
Why does Bonneville County have so many water violations?
Bonneville County has 29 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 Bonneville County rank for water quality in Idaho?
Bonneville County ranks #14 out of 44 counties in Idaho by SDWIS water quality score (1 = best). With a score of 44.7/100, 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

Jerome County

Idaho

D

47.6

Water score

Minidoka County

Idaho

D

48.4

Water score

Bear Lake County

Idaho

D

48.5

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 and 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.

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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