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Federal water data

County water report

Sussex County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for Sussex County, Delaware.

Water grade

C

Water score

55.6

State rank

#3

of 3

Health violations

34

EPA SDWIS, 5-year lookback

Watershed impaired

64.3%

238 water bodies assessed

Monitoring sites

211

87,538 recent measurements

Live streamflow

43%

NANTICOKE RIVER NEAR BRIDGEVILLE, DE

Water at a glance

Key Water Indicators for Sussex County

EPA SDWIS

Safety Grade

C

Score: 55.6 / 100

EPA SDWIS

Active Violations

34

5-year health-based lookback

EPA ATTAINS

Watershed Health

64% impaired

238 bodies assessed

USGS NWIS

Streamflow Snapshot

43% of mean

NANTICOKE RIVER NEAR BRIDGEVILLE, DE

EPA WQP

Monitoring Sites

211

87,538 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.

55.6/100

Health violations

34

Health-based violations

Violations per 100K served

9.9

Population-normalized SDWIS rate

Editorial analysis

Understanding Sussex County’s Water

Drinking Water Quality Overview

EPA SDWIS

Sussex County's drinking water earned a C grade, scoring 55.6 out of 100. Over the past five years, EPA SDWIS records 34 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 large majority — 64.3% — of assessed waterways are impaired (153 of 238 water bodies) across Sussex County's watersheds. The leading impairment causes are nutrients and habitat assessment. 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 2026-05-14T14:15:00.000-04:00) puts NANTICOKE RIVER at 40.2 cfs — well below its long-term average at 43% 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. Sussex County has extensive coverage with 211 active monitoring sites with 87,538 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 Sussex County

Water Verdict

Sussex County receives a fair water quality assessment with a grade of C and a score of 55.6 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

Sussex County has recorded 34 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 9.9 violations per 100,000 people served, this rate is high and signals significant water quality management issues.

Consumer Guidance

Tap water in Sussex County meets baseline standards but the compliance record shows room for improvement, with a Grade C rating. Sussex County's drinking-water compliance score is 55.6 out of 100. The violation rate for Sussex County is 9.9 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. Nutrients is the leading impairment cause in Sussex County's watershed. With 211 active water-quality monitoring sites in Sussex County, data coverage is strong. A pipeline streamflow snapshot from the NANTICOKE RIVER gauge is also available on this page.

Regional Context

Sussex County has poorer water quality than the average county in Delaware. Its water score is 10.5 points lower than the state average, suggesting more challenges with contamination control or infrastructure than 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 Sussex County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    Nutrient pollution

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

  • 2

    Habitat Assessment

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

  • 3

    Enterococcus bacteria

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

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for Sussex County

EPA How's My Waterway

Interactive watershed health data for Sussex County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Sussex County

Consumer Confidence Reports (DE)

Annual water quality reports from utilities in Delaware

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

64.3%

153 of 238 assessed

High concern

Top Impairment Causes

  • 1

    NUTRIENTS

  • 2

    HABITAT ASSESSMENT

  • 3

    ENTEROCOCCUS

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

211

Active in the past 5 years

Measurements Recorded

88K

87,538 total readings

Most Measured

  • Physical
  • Nutrient
  • Inorganics, Major, 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

40.2cfs

May 14, 6:15 PM UTC

vs Long-Term Average

43%

Well below typical

Primary Streamgage

NANTICOKE RIVER NEAR BRIDGEVILLE, DE

USGS site
01487000
Drainage area
75.4 sq mi
Long-term mean
94.7 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 Sussex 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 Sussex County, Delaware?
Sussex County, Delaware has a drinking-water quality grade of C with a score of 55.6/100, based on EPA SDWIS compliance data. The county has 34 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 Sussex County?
Sussex County has 34 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 Sussex County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 64.3% of Sussex County's 238 assessed water bodies are classified as impaired (153 impaired). The top reported causes are NUTRIENTS, HABITAT ASSESSMENT, ENTEROCOCCUS. 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 Sussex County?
EPA's Water Quality Portal records 87,538 measurements from 211 monitoring sites in Sussex County over the past five years. The most frequently measured characteristic groups are Physical, Nutrient, Inorganics, Major, 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 Sussex County right now?
Sussex County's primary USGS streamgage on the NANTICOKE RIVER has a pipeline snapshot of 40.2 cubic feet per second — 43% of the long-term mean of 94.65 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 Sussex County water compare to the Delaware average?
Sussex County's SDWIS water quality score of 55.6/100 is lower than the Delaware state average of 66.1. The average water quality grade across Delaware is C, based on data from 3 counties with available SDWIS data.
Is tap water safe to drink in Sussex County?
Based on EPA SDWIS data, Sussex County has a water quality grade of C (55.6/100). 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 Sussex County have so many water violations?
Sussex County has 34 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 Sussex County rank for water quality in Delaware?
Sussex County ranks #3 out of 3 counties in Delaware by SDWIS water quality score (1 = best). With a score of 55.6/100, it falls in the bottom 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

Kent County

Delaware

C

56.8

Water score

New Castle County

Delaware

A

86.0

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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