County water report

St. Lawrence County Water Report

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

Water grade

Water score

68.6

State rank

of 57

Health violations

EPA SDWIS, 5-year lookback

Watershed impaired

Not reported

EPA ATTAINS coverage varies by state

Monitoring sites

74,002 recent measurements

Live streamflow

No gauge

ST. LAWRENCE R AT CORNWALL ONT NR MASSENA NY

Water at a glance

Key Water Indicators for St. Lawrence County

EPA SDWIS

Safety Grade

Score: 68.6 / 100

EPA SDWIS

Active Violations

5-year health-based lookback

EPA ATTAINS

Watershed Health

Not reported

Coverage varies by state

USGS NWIS

Streamflow Snapshot

No gauge

ST. LAWRENCE R AT CORNWALL ONT NR MASSENA NY

EPA WQP

Monitoring Sites

74,002 recent readings

Source: EPA SDWIS · Safe Drinking Water Information System

Drinking Water Compliance

Compliance grade

Based on EPA SDWIS compliance history.

Water score

Higher scores indicate cleaner recent compliance records.

68.6/100

Health violations

Health-based violations

Violations per 100K served

1.6

Population-normalized SDWIS rate

Data center water stress

St. Lawrence County has 1 facility in the DCWSI dataset.

ByCounty's DCWSI ranks this county #1060 nationally by combining its water score with mapped data center density.

DCWSI

41.2

0-100 index

Facility count

0.0 density percentile

Discharge estimate

Not reported

EPA CWA fields where available

Water vs median

+18.6

Compared with US county median

Named operators

Clarkson University

Mapped facilities

Old Main
Clarkson University
OSM

See the St. Lawrence County data-center report Review methodology

Data Center Water Budget Calculator

Estimate daily water use for a hypothetical facility in St. Lawrence County.

Facility size: 100 MW

1 MW1,000 MW

Cooling type

Utilization: 70%

40%100%

799K gallons/dayModerate Impact

Your facility would use 8.8% of this county's industrial water baseline — manageable but worth monitoring against drought trends.

8.8% of county industrial baseline8.32 Mgal/day remaining headroom

Based on USGS 2020 water-use data and EPA-standard cooling intensity constants. Not a substitute for site-specific water rights analysis.

Editorial analysis

Understanding St. Lawrence County’s Water

Drinking Water Quality Overview

EPA SDWIS

St. Lawrence County earns a B grade for drinking water quality, scoring 68.6 out of 100. Over the past five years, EPA SDWIS records 1 health-based violation — a single incident worth monitoring.

Monitoring Network

EPA WQP

EPA's Water Quality Portal (WQP) aggregates monitoring data from federal, state, and tribal agencies. St. Lawrence County has moderate coverage with 46 active monitoring sites with 74,002 recent measurements on record. Predominant monitoring categories include physical and organics, pesticide. 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 St. Lawrence County

Water Verdict

St. Lawrence County, New York receives a fair water quality assessment with a grade of B and a score of 68.6 out of 100. The water supply meets baseline federal standards, but there may be periods of elevated contaminant levels or infrastructure concerns worth monitoring. The county's primary USGS gauge drains roughly 298,800 square miles of upstream watershed, giving local source waters a regional footprint.

Violation Context

EPA SDWIS records for St. Lawrence County, New York show 1 health-based violation, meaning a water system experienced at least one exceedance of federal contaminant limits or treatment requirements. At 1.6 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: 74,002 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 St. Lawrence County scores well above average for drinking-water safety. St. Lawrence County's drinking-water compliance score is 68.6 out of 100. With 1 recorded health violation, the water supply is generally reliable. The violation rate for St. Lawrence County is 1.6 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. With 46 active water-quality monitoring sites in St. Lawrence County, data coverage is strong. Live streamflow monitoring from the ST. LAWRENCE R gauge is also available on this page.

Regional Context

St. Lawrence County has better water quality than the average county in New York. Its water score is 28.5 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 St. Lawrence County's water environment

Official EPA Resources for St. Lawrence County

EPA How's My Waterway

Interactive watershed health data for St. Lawrence County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for St. Lawrence County

Consumer Confidence Reports (NY)

Annual water quality reports from utilities in New York

Past 5 years

Water Quality Monitoring

Monitoring Sites

Active in the past 5 years

Measurements Recorded

74K

74,002 total readings

Most Measured

Physical
Organics, Pesticide
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).

Free tool

Estimate Your Water Costs

Water Cost Estimate

Household size

3 people · ~225 gal/day

Filter type

Annual Total

$558

Monthly

$47

Water Bill

$558/yr

Filter Cost

$0/yr

Safety Grade for St. Lawrence 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.

Try the full calculator →

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Frequently Asked Questions

What is the water quality in St. Lawrence County, New York?

St. Lawrence County, New York has a drinking-water quality grade of B with a score of 68.6/100, based on EPA SDWIS compliance data. The county has 1 health-based drinking water violation over the past 5 years. Watershed health, monitoring records, and streamflow snapshots are reported separately on this page.

Are there any water violations in St. Lawrence County?

St. Lawrence County has 1 health-based drinking water violation 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 St. Lawrence County?

EPA's Water Quality Portal records 74,002 measurements from 46 monitoring sites in St. Lawrence County over the past five years. The most frequently measured characteristic groups are Physical, Organics, Pesticide, 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.

How does St. Lawrence County water compare to the New York average?

St. Lawrence County's SDWIS water quality score of 68.6/100 is higher 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 St. Lawrence County?

Based on EPA SDWIS data, St. Lawrence County has a water quality grade of B (68.6/100). 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 St. Lawrence County have clean drinking water?

St. Lawrence County has 1 health-based drinking water violation according to EPA records. With a water quality score of 68.6/100 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 St. Lawrence County rank for water quality in New York?

St. Lawrence County ranks #7 out of 57 counties in New York by SDWIS water quality score (1 = best). With a score of 68.6/100, 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

Monroe County

New York

68.6

Water score

Nassau County

New York

68.8

Water score

Chemung County

New York

69.5

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.

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 May 14, 2026Reviewed by Evan Brooks, Data Editor

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