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Federal water data

County water report

Bannock County Water Report

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

Water grade

C

Water score

53.8

State rank

#8

of 44

Health violations

9

EPA SDWIS, 5-year lookback

Watershed impaired

53.6%

360 water bodies assessed

Monitoring sites

61

4,559 recent measurements

Live streamflow

28%

PORTNEUF RIVER NR TYHEE ID

Water at a glance

Key Water Indicators for Bannock County

EPA SDWIS

Safety Grade

C

Score: 53.8 / 100

EPA SDWIS

Active Violations

9

5-year health-based lookback

EPA ATTAINS

Watershed Health

54% impaired

360 bodies assessed

USGS NWIS

Streamflow Snapshot

28% of mean

PORTNEUF RIVER NR TYHEE ID

EPA WQP

Monitoring Sites

61

4,559 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

C

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

53.8/100

Health violations

9

Health-based violations

Violations per 100K served

11.5

Population-normalized SDWIS rate

Editorial analysis

Understanding Bannock County’s Water

Drinking Water Quality Overview

EPA SDWIS

Bannock County's drinking water earned a C grade, scoring 53.8 out of 100. Over the past five years, EPA SDWIS records 9 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 53.6% of assessed waterways are impaired (193 of 360 water bodies) across Bannock County's watersheds. The leading impairment causes are phosphorus, total and sedimentation/siltation. 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 2026-05-14T12:00:00.000-06:00) puts PORTNEUF RIVER at 116.0 cfs — well below its long-term average at 28% of mean — low-flow conditions worth noting for water-dependent ecosystems. 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. Bannock County has extensive coverage with 61 active monitoring sites with 4,559 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 Bannock County

Water Verdict

Bannock County receives a below-average water quality assessment with a grade of C and a score of 53.8 out of 100. Residents should review their utility's Consumer Confidence Report and may want to consider additional water filtration for drinking.

Violation Context

Bannock County has recorded 9 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 11.5 violations per 100,000 people served, this rate is high and signals significant water quality management issues.

Consumer Guidance

Tap water in Bannock County meets baseline standards but the compliance record shows room for improvement, with a Grade C rating. Bannock County's drinking-water compliance score is 53.8 out of 100. The violation rate for Bannock County is 11.5 per 100,000 people served. Residents who are immunocompromised, pregnant, or have young children may benefit from using an NSF 53-certified filter. Contacting your local utility for the current Consumer Confidence Report will confirm which specific violations were recorded and whether they have been resolved. Phosphorus, Total is the leading impairment cause in Bannock County's watershed. With 61 active water-quality monitoring sites in Bannock County, data coverage is strong. A pipeline streamflow snapshot from the PORTNEUF RIVER gauge is also available on this page.

Regional Context

Bannock County has better water quality than the average county in Idaho. Its water score is 21.2 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 Bannock County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    Phosphorus (excess nutrients)

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

  • 2

    Sedimentation and siltation

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

  • 3

    E. coli (bacteria)

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

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for Bannock County

EPA How's My Waterway

Interactive watershed health data for Bannock County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Bannock County

Consumer Confidence Reports (ID)

Annual water quality reports from utilities in Idaho

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

53.6%

193 of 360 assessed

Moderate concern

Top Impairment Causes

  • 1

    PHOSPHORUS, TOTAL

  • 2

    SEDIMENTATION/SILTATION

  • 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

61

Active in the past 5 years

Measurements Recorded

4.6K

4,559 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

116cfs

May 14, 6:00 PM UTC

vs Long-Term Average

28%

Well below typical

Primary Streamgage

PORTNEUF RIVER NR TYHEE ID

USGS site
13075910
Drainage area
1,305 sq mi
Long-term mean
421 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.

Free tool

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 Bannock County:D — Poor

Elevated violations or significant watershed impairment.

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 Bannock County, Idaho?
Bannock County, Idaho has a drinking-water quality grade of C with a score of 53.8/100, based on EPA SDWIS compliance data. The county has 9 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 Bannock County?
Bannock County has 9 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 Bannock County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 53.6% of Bannock County's 360 assessed water bodies are classified as impaired (193 impaired). The top reported causes are PHOSPHORUS, TOTAL, SEDIMENTATION/SILTATION, 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 Bannock County?
EPA's Water Quality Portal records 4,559 measurements from 61 monitoring sites in Bannock 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 Bannock County right now?
Bannock County's primary USGS streamgage on the PORTNEUF RIVER has a pipeline snapshot of 116 cubic feet per second — 28% of the long-term mean of 420.74 cfs. This is well below typical — often a signal of drought stress on source water. For the latest gauge feed, visit waterdata.usgs.gov.
How does Bannock County water compare to the Idaho average?
Bannock County's SDWIS water quality score of 53.8/100 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 Bannock County?
Based on EPA SDWIS data, Bannock County has a water quality grade of C (53.8/100). This indicates moderate compliance. Some violations have been recorded but overall standards are maintained. 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 Bannock County have so many water violations?
Bannock County has 9 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 Bannock County rank for water quality in Idaho?
Bannock County ranks #8 out of 44 counties in Idaho by SDWIS water quality score (1 = best). With a score of 53.8/100, 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

Twin Falls County

Idaho

C

52.8

Water score

Ada County

Idaho

C

55.6

Water score

Gem County

Idaho

C

51.2

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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