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Federal water data

County water report

Warren County Water Report

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

Water grade

B

Water score

64.1

State rank

#6

of 21

Health violations

3

EPA SDWIS, 5-year lookback

Watershed impaired

100.0%

3 water bodies assessed

Monitoring sites

120

25,280 recent measurements

Live streamflow

83%

Delaware River at Riegelsville NJ

Water at a glance

Key Water Indicators for Warren County

EPA SDWIS

Safety Grade

B

Score: 64.1 / 100

EPA SDWIS

Active Violations

3

5-year health-based lookback

EPA ATTAINS

Watershed Health

100% impaired

3 bodies assessed

USGS NWIS

Streamflow Snapshot

83% of mean

Delaware River at Riegelsville NJ

EPA WQP

Monitoring Sites

120

25,280 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

B

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

64.1/100

Health violations

3

Health-based violations

Violations per 100K served

4.1

Population-normalized SDWIS rate

Editorial analysis

Understanding Warren County’s Water

Drinking Water Quality Overview

EPA SDWIS

Warren County earns a B grade for drinking water quality, scoring 64.1 out of 100. Over the past five years, EPA SDWIS records 3 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 large majority — 100.0% — of assessed waterways are impaired (3 of 3 water bodies) across Warren County's watersheds. The leading impairment causes are ddt in fish tissue and pcbs in fish tissue. 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 2026-05-14T15:00:00.000-04:00) puts Delaware River at 10.6k cfs — running somewhat below its historical average at 83% 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. Warren County has extensive coverage with 120 active monitoring sites with 25,280 recent measurements on record. Predominant monitoring categories include physical and organics, pcbs. 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 Warren County

Water Verdict

Warren County receives a fair water quality assessment with a grade of B and a score of 64.1 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

Warren County has recorded 3 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 4.1 violations per 100,000 people served, this rate is moderate and suggests recurring water quality challenges.

Consumer Guidance

Tap water in Warren County scores well above average for drinking-water safety. Warren County's drinking-water compliance score is 64.1 out of 100. With 3 recorded health violations, the water supply is generally reliable. The violation rate for Warren County is 4.1 per 100,000 people served. Households with infants, pregnant individuals, or immunocompromised members may want to use an NSF 53-certified pitcher filter as a low-cost precaution. Ddt in Fish Tissue is the leading impairment cause in Warren County's watershed. With 120 active water-quality monitoring sites in Warren County, data coverage is strong. A pipeline streamflow snapshot from the Delaware River gauge is also available on this page.

Regional Context

Warren County has better water quality than the average county in New Jersey. Its water score is 8.4 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 Warren County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    Ddt in Fish Tissue

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

  • 2

    Pcbs in Fish Tissue

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

  • 3

    Chlordane in Fish Tissue

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

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for Warren County

EPA How's My Waterway

Interactive watershed health data for Warren County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Warren County

Consumer Confidence Reports (NJ)

Annual water quality reports from utilities in New Jersey

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

100.0%

3 of 3 assessed

High concern

Top Impairment Causes

  • 1

    DDT IN FISH TISSUE

  • 2

    PCBS IN FISH TISSUE

  • 3

    CHLORDANE IN FISH TISSUE

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

120

Active in the past 5 years

Measurements Recorded

25K

25,280 total readings

Most Measured

  • Physical
  • Organics, PCBs
  • Nutrient

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

10.6Kcfs

May 14, 7:00 PM UTC

vs Long-Term Average

83%

Below typical

Primary Streamgage

Delaware River at Riegelsville NJ

USGS site
01457500
Drainage area
6,328 sq mi
Long-term mean
12.7K 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 Warren 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 Warren County, New Jersey?
Warren County, New Jersey has a drinking-water quality grade of B with a score of 64.1/100, based on EPA SDWIS compliance data. The county has 3 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 Warren County?
Warren County has 3 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 Warren County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 100.0% of Warren County's 3 assessed water bodies are classified as impaired (3 impaired). The top reported causes are DDT IN FISH TISSUE, PCBS IN FISH TISSUE, CHLORDANE IN FISH TISSUE. 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 Warren County?
EPA's Water Quality Portal records 25,280 measurements from 120 monitoring sites in Warren County over the past five years. The most frequently measured characteristic groups are Physical, Organics, PCBs, Nutrient. 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 Warren County right now?
Warren County's primary USGS streamgage on the Delaware River has a pipeline snapshot of 10,600 cubic feet per second — 83% of the long-term mean of 12,741.67 cfs. Flow is within typical range for this gauge. For the latest gauge feed, visit waterdata.usgs.gov.
How does Warren County water compare to the New Jersey average?
Warren County's SDWIS water quality score of 64.1/100 is higher than the New Jersey state average of 55.7. The average water quality grade across New Jersey is D, based on data from 21 counties with available SDWIS data.
Is tap water safe to drink in Warren County?
Based on EPA SDWIS data, Warren County has a water quality grade of B (64.1/100). 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 Warren County have clean drinking water?
Warren County has 3 health-based drinking water violations according to EPA records. With a water quality score of 64.1/100 and grade B, 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 Warren County rank for water quality in New Jersey?
Warren County ranks #6 out of 21 counties in New Jersey by SDWIS water quality score (1 = best). With a score of 64.1/100, 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

Ocean County

New Jersey

B

63.0

Water score

Mercer County

New Jersey

B

62.3

Water score

Middlesex County

New Jersey

C

61.7

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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