waterbycounty
Federal water data

County water report

Sullivan County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for Sullivan County, New Hampshire.

Water grade

C

Water score

57.8

State rank

#1

of 10

Health violations

2

EPA SDWIS, 5-year lookback

Watershed impaired

50.0%

2 water bodies assessed

Monitoring sites

198

14,844 recent measurements

Live streamflow

107%

SUGAR RIVER AT WEST CLAREMONT, NH

Water at a glance

Key Water Indicators for Sullivan County

EPA SDWIS

Safety Grade

C

Score: 57.8 / 100

EPA SDWIS

Active Violations

2

5-year health-based lookback

EPA ATTAINS

Watershed Health

50% impaired

2 bodies assessed

USGS NWIS

Streamflow Snapshot

107% of mean

SUGAR RIVER AT WEST CLAREMONT, NH

EPA WQP

Monitoring Sites

198

14,844 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.

57.8/100

Health violations

2

Health-based violations

Violations per 100K served

8.2

Population-normalized SDWIS rate

Editorial analysis

Understanding Sullivan County’s Water

Drinking Water Quality Overview

EPA SDWIS

Sullivan County's drinking water earned a C grade, scoring 57.8 out of 100. Over the past five years, EPA SDWIS records 2 health-based violations — a small cluster that warrants attention.

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 50.0% of assessed waterways are impaired (1 of 2 water bodies) across Sullivan County's watersheds. The leading impairment causes are mercury - fish consumption advisory and ph. 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 2026-05-14T14:30:00.000-04:00) puts SUGAR RIVER at 457.0 cfs — near its historical average at 107% of mean flow. 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. Sullivan County has extensive coverage with 198 active monitoring sites with 14,844 recent measurements on record. Predominant monitoring categories include physical and nutrient. 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 Sullivan County

Water Verdict

Sullivan County receives a fair water quality assessment with a grade of C and a score of 57.8 out of 100. The water supply meets baseline federal standards, but there may be periods of elevated contaminant levels or infrastructure concerns worth monitoring.

Violation Context

Sullivan County has recorded 2 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 8.2 violations per 100,000 people served, this rate is high and signals significant water quality management issues.

Consumer Guidance

Tap water in Sullivan County meets baseline standards but the compliance record shows room for improvement, with a Grade C rating. Sullivan County's drinking-water compliance score is 57.8 out of 100. The violation rate for Sullivan County is 8.2 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. Mercury - Fish Consumption Advisory is the leading impairment cause in Sullivan County's watershed. With 198 active water-quality monitoring sites in Sullivan County, data coverage is strong. A pipeline streamflow snapshot from the SUGAR RIVER gauge is also available on this page.

Regional Context

Sullivan County has better water quality than the average county in New Hampshire. Its water score is 24.6 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 Sullivan County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    Mercury - Fish Consumption Advisory

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

  • 2

    pH imbalance

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

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for Sullivan County

EPA How's My Waterway

Interactive watershed health data for Sullivan County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Sullivan County

Consumer Confidence Reports (NH)

Annual water quality reports from utilities in New Hampshire

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

50.0%

1 of 2 assessed

Moderate concern

Top Impairment Causes

  • 1

    MERCURY - FISH CONSUMPTION ADVISORY

  • 2

    PH

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

198

Active in the past 5 years

Measurements Recorded

15K

14,844 total readings

Most Measured

  • Physical
  • Nutrient
  • Inorganics, Major, Non-metals

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

457cfs

May 14, 6:30 PM UTC

vs Long-Term Average

107%

Near typical

Primary Streamgage

SUGAR RIVER AT WEST CLAREMONT, NH

USGS site
01152500
Drainage area
269 sq mi
Long-term mean
426 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 Sullivan 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.

Try the full calculator →

Improve your water quality at home

Berkey filters remove 99.9%+ of contaminants from tap water.

Shop Berkey →

Sponsored

Test your tap water

Tap Score provides professional mail-in water testing.

Get Tested →

Frequently Asked Questions

What is the water quality in Sullivan County, New Hampshire?
Sullivan County, New Hampshire has a drinking-water quality grade of C with a score of 57.8/100, 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 streamflow snapshots are reported separately on this page.
Are there any water violations in Sullivan County?
Sullivan 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 Sullivan County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 50.0% of Sullivan County's 2 assessed water bodies are classified as impaired (1 impaired). The top reported causes are MERCURY - FISH CONSUMPTION ADVISORY, PH. 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 Sullivan County?
EPA's Water Quality Portal records 14,844 measurements from 198 monitoring sites in Sullivan County over the past five years. The most frequently measured characteristic groups are Physical, Nutrient, Inorganics, Major, Non-metals. 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 Sullivan County right now?
Sullivan County's primary USGS streamgage on the SUGAR RIVER has a pipeline snapshot of 457 cubic feet per second — 107% of the long-term mean of 426.04 cfs. Flow is within typical range for this gauge. For the latest gauge feed, visit waterdata.usgs.gov.
How does Sullivan County water compare to the New Hampshire average?
Sullivan County's SDWIS water quality score of 57.8/100 is higher than the New Hampshire state average of 33.2. The average water quality grade across New Hampshire is F, based on data from 10 counties with available SDWIS data.
Is tap water safe to drink in Sullivan County?
Based on EPA SDWIS data, Sullivan County has a water quality grade of C (57.8/100). 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).
Does Sullivan County have clean drinking water?
Sullivan County has 2 health-based drinking water violations according to EPA records. With a water quality score of 57.8/100 and grade C, 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 Sullivan County rank for water quality in New Hampshire?
Sullivan County ranks #1 out of 10 counties in New Hampshire by SDWIS water quality score (1 = best). With a score of 57.8/100, 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

Cheshire County

New Hampshire

C

51.2

Water score

Coos County

New Hampshire

D

49.9

Water score

Hillsborough County

New Hampshire

D

41.5

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

Explore more data for Sullivan County

Property TaxCost of LivingCrime RateIncomeHealthSchoolsDisaster RiskWeatherCounty Score