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County water report

Barnstable County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for Barnstable County, Massachusetts.

Water grade

A

Water score

71.5

State rank

#4

of 14

Health violations

2

EPA SDWIS, 5-year lookback

Watershed impaired

Not reported

EPA ATTAINS coverage varies by state

Monitoring sites

1,135

90,691 recent measurements

Live streamflow

114%

HERRING RIVER AT NORTH HARWICH, MA

Water at a glance

Key Water Indicators for Barnstable County

EPA SDWIS

Safety Grade

A

Score: 71.5 / 100

EPA SDWIS

Active Violations

2

5-year health-based lookback

EPA ATTAINS

Watershed Health

Not reported

Coverage varies by state

USGS NWIS

Streamflow Snapshot

114% of mean

HERRING RIVER AT NORTH HARWICH, MA

EPA WQP

Monitoring Sites

1,135

90,691 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

A

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

71.5/100

Health violations

2

Health-based violations

Violations per 100K served

0.3

Population-normalized SDWIS rate

Editorial analysis

Understanding Barnstable County’s Water

Drinking Water Quality Overview

EPA SDWIS

Barnstable County earns an A grade for drinking water quality, scoring 71.5 out of 100. Over the past five years, EPA SDWIS records 2 health-based violations — a small cluster that warrants attention.

River & Streamflow Status

USGS NWIS

USGS NWIS gauge data (as of 2026-05-14T14:45:00.000-04:00) puts HERRING RIVER at 11.1 cfs — flowing above its historical average at 114% 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. Barnstable County has extensive coverage with 1,135 active monitoring sites with 90,691 recent measurements on record. Predominant monitoring categories include nutrient and physical. 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 Barnstable County

Water Verdict

Barnstable County, Massachusetts receives a good water quality assessment with a grade of A and a score of 71.5 out of 100. While the water supply is generally safe, occasional monitoring gaps or minor contaminant detections may occur. The county's primary USGS gauge drains roughly 9 square miles of upstream watershed, giving local source waters a regional footprint. At the most recent USGS reading, local streamflow was running above its historical mean at 113.6%.

Violation Context

EPA SDWIS records for Barnstable County, Massachusetts show 2 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 0.3 violations per 100,000 people served, this rate is relatively low compared to many U.S. counties. This compliance record sits alongside an unusually deep monitoring archive: 90,691 water-quality results have been logged across the county in the EPA Water Quality Portal over the past five years.

Consumer Guidance

Tap water in Barnstable County earns a Grade A overall with a small number of isolated health violations in the recent record. Barnstable County's drinking-water compliance score is 71.5 out of 100. The violation rate for Barnstable County is 0.3 per 100,000 people served. These violations were likely resolved quickly; Grade A reflects a strong multi-year compliance trend. Reviewing the most recent Consumer Confidence Report will show exactly which systems were affected and what corrective action was taken. With 1,135 active water-quality monitoring sites in Barnstable County, data coverage is strong. A pipeline streamflow snapshot from the HERRING RIVER gauge is also available on this page.

Regional Context

Barnstable County has water quality close to the average county in Massachusetts. Its water score is within 2.4 points of the state average, meaning its overall water system performance is broadly representative of Massachusetts as a whole.

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 Barnstable County's water environment

Official EPA Resources for Barnstable County

EPA How's My Waterway

Interactive watershed health data for Barnstable County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Barnstable County

Consumer Confidence Reports (MA)

Annual water quality reports from utilities in Massachusetts

Past 5 years

Water Quality Monitoring

Monitoring Sites

1,135

Active in the past 5 years

Measurements Recorded

91K

90,691 total readings

Most Measured

  • Nutrient
  • Physical
  • Organics, Other

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

11.1cfs

May 14, 6:45 PM UTC

vs Long-Term Average

114%

Above typical

Primary Streamgage

HERRING RIVER AT NORTH HARWICH, MA

USGS site
01105880
Drainage area
9.4 sq mi
Long-term mean
9.77 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 Barnstable 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 Barnstable County, Massachusetts?
Barnstable County, Massachusetts has a drinking-water quality grade of A with a score of 71.5/100, 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 Barnstable County?
Barnstable 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 much water-quality monitoring happens in Barnstable County?
EPA's Water Quality Portal records 90,691 measurements from 1,135 monitoring sites in Barnstable County over the past five years. The most frequently measured characteristic groups are Nutrient, Physical, Organics, Other. 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 Barnstable County right now?
Barnstable County's primary USGS streamgage on the HERRING RIVER has a pipeline snapshot of 11.1 cubic feet per second — 114% of the long-term mean of 9.77 cfs. Flow is within typical range for this gauge. For the latest gauge feed, visit waterdata.usgs.gov.
How does Barnstable County water compare to the Massachusetts average?
Barnstable County's SDWIS water quality score of 71.5/100 is higher than the Massachusetts state average of 69.1. The average water quality grade across Massachusetts is C, based on data from 14 counties with available SDWIS data.
Is tap water safe to drink in Barnstable County?
Based on EPA SDWIS data, Barnstable County has a water quality grade of A (71.5/100). This indicates good to excellent water quality with strong SDWIS compliance. 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 Barnstable County have clean drinking water?
Barnstable County has 2 health-based drinking water violations according to EPA records. With a water quality score of 71.5/100 and grade A, 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 Barnstable County rank for water quality in Massachusetts?
Barnstable County ranks #4 out of 14 counties in Massachusetts by SDWIS water quality score (1 = best). With a score of 71.5/100, 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

Essex County

Massachusetts

A

70.4

Water score

Middlesex County

Massachusetts

B

68.0

Water score

Hampshire County

Massachusetts

B

67.5

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.

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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