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Federal water data

County water report

Ontario County Water Report

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

Water grade

F

Water score

29.0

State rank

#40

of 57

Health violations

64

EPA SDWIS, 5-year lookback

Watershed impaired

Not reported

EPA ATTAINS coverage varies by state

Monitoring sites

5

1,079 recent measurements

Live streamflow

437%

CANANDAIGUA OUTLET AT CHAPIN NY

Water at a glance

Key Water Indicators for Ontario County

EPA SDWIS

Safety Grade

F

Score: 29.0 / 100

EPA SDWIS

Active Violations

64

5-year health-based lookback

EPA ATTAINS

Watershed Health

Not reported

Coverage varies by state

USGS NWIS

Streamflow Snapshot

437% of mean

CANANDAIGUA OUTLET AT CHAPIN NY

EPA WQP

Monitoring Sites

5

1,079 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

F

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

29.0/100

Health violations

64

Health-based violations

Violations per 100K served

71.4

Population-normalized SDWIS rate

Editorial analysis

Understanding Ontario County’s Water

Drinking Water Quality Overview

EPA SDWIS

Ontario County's water systems carry a failing grade, scoring 29.0 out of 100. Over the past five years, EPA SDWIS records 64 health-based violations — a pattern that public water utilities are required to disclose and correct.

River & Streamflow Status

USGS NWIS

USGS NWIS gauge data (as of 2026-05-14T13:30:00.000-05:00) puts CANANDAIGUA OUTLET at 709.0 cfs — running significantly above its long-term average at 437% 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. Ontario County has limited coverage with 5 active monitoring sites with 1,079 recent measurements on record. Predominant monitoring categories include organics, pesticide and organics, other. 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 Ontario County

Water Verdict

Ontario County receives a poor water quality assessment with a grade of F and a score of 29.0 out of 100. The water supply has documented quality issues. Residents are strongly encouraged to use filtered or bottled water for drinking and to stay informed about utility improvement plans.

Violation Context

Ontario County has recorded 64 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 71.4 violations per 100,000 people served, this rate is high and signals significant water quality management issues.

Consumer Guidance

Ontario County has a Grade F compliance record with 64 health-based violations — among the highest levels in the country. Ontario County's drinking-water compliance score is 29.0 out of 100. The violation rate for Ontario County is 71.4 per 100,000 people served. Residents are strongly advised to use a certified NSF 58 reverse-osmosis filter or bottled water for all drinking and cooking until violations are corrected. Contacting the New York Department of Environmental Quality or Health can expedite utility compliance action. There are 5 active water-quality monitoring sites in Ontario County. A pipeline streamflow snapshot from the CANANDAIGUA OUTLET gauge is also available on this page.

Regional Context

Ontario County has poorer water quality than the average county in New York. Its water score is 11.1 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 Ontario County's water environment

Official EPA Resources for Ontario County

EPA How's My Waterway

Interactive watershed health data for Ontario County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Ontario County

Consumer Confidence Reports (NY)

Annual water quality reports from utilities in New York

Past 5 years

Water Quality Monitoring

Monitoring Sites

5

Active in the past 5 years

Measurements Recorded

1.1K

1,079 total readings

Most Measured

  • Organics, Pesticide
  • Organics, Other
  • Inorganics, Minor, 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

709cfs

May 14, 6:30 PM UTC

vs Long-Term Average

437%

Well above typical

Primary Streamgage

CANANDAIGUA OUTLET AT CHAPIN NY

USGS site
04235000
Drainage area
195 sq mi
Long-term mean
162 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

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Annual Total

$558

Monthly

$47

Water Bill

$558/yr

Filter Cost

$0/yr

Safety Grade for Ontario County:F — Failing

High violation count or severe watershed conditions.

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 Ontario County, New York?
Ontario County, New York has a drinking-water quality grade of F with a score of 29.0/100, based on EPA SDWIS compliance data. The county has 64 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 Ontario County?
Ontario County has 64 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 Ontario County?
EPA's Water Quality Portal records 1,079 measurements from 5 monitoring sites in Ontario County over the past five years. The most frequently measured characteristic groups are Organics, Pesticide, Organics, Other, Inorganics, Minor, 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 Ontario County right now?
Ontario County's primary USGS streamgage on the CANANDAIGUA OUTLET has a pipeline snapshot of 709 cubic feet per second — 437% of the long-term mean of 162.13 cfs. This is well above typical — often a signal of recent precipitation or storm runoff. For the latest gauge feed, visit waterdata.usgs.gov.
How does Ontario County water compare to the New York average?
Ontario County's SDWIS water quality score of 29.0/100 is lower than the New York state average of 40.1. The average water quality grade across New York is D, based on data from 57 counties with available SDWIS data.
Is tap water safe to drink in Ontario County?
Based on EPA SDWIS data, Ontario County has a water quality grade of F (29.0/100). This indicates below-average compliance with significant violations. Residents may want to consider home water filtration or independent testing. 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 Ontario County have so many water violations?
Ontario County has 64 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 Ontario County rank for water quality in New York?
Ontario County ranks #40 out of 57 counties in New York by SDWIS water quality score (1 = best). With a score of 29.0/100, 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

Seneca County

New York

F

28.8

Water score

Steuben County

New York

F

28.0

Water score

Delaware County

New York

F

30.9

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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