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County water report

Weld County Water Report

Drinking-water compliance, watershed health, monitoring records, and river conditions for Weld County, Colorado.

Water grade

C

Water score

55.2

State rank

#16

of 64

Health violations

37

EPA SDWIS, 5-year lookback

Watershed impaired

48.9%

188 water bodies assessed

Monitoring sites

119

51,240 recent measurements

Live streamflow

47%

SOUTH PLATTE RIVER AT FORT LUPTON, CO.

Water at a glance

Key Water Indicators for Weld County

EPA SDWIS

Safety Grade

C

Score: 55.2 / 100

EPA SDWIS

Active Violations

37

5-year health-based lookback

EPA ATTAINS

Watershed Health

49% impaired

188 bodies assessed

USGS NWIS

Streamflow Snapshot

47% of mean

SOUTH PLATTE RIVER AT FORT LUPTON, CO.

EPA WQP

Monitoring Sites

119

51,240 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.

55.2/100

Health violations

37

Health-based violations

Violations per 100K served

10.3

Population-normalized SDWIS rate

Editorial analysis

Understanding Weld County’s Water

Drinking Water Quality Overview

EPA SDWIS

Weld County's drinking water earned a C grade, scoring 55.2 out of 100. Over the past five years, EPA SDWIS records 37 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 substantial 48.9% of assessed waterways are impaired (92 of 188 water bodies) across Weld County's watersheds. The leading impairment causes are arsenic and escherichia coli (e. coli). 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 2026-05-14T13:00:00.000-06:00) puts SOUTH PLATTE RIVER at 190.0 cfs — well below its long-term average at 47% 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. Weld County has extensive coverage with 119 active monitoring sites with 51,240 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 Weld County

Water Verdict

Weld County receives a fair water quality assessment with a grade of C and a score of 55.2 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

Weld County has recorded 37 health-based violations, indicating multiple instances where federal contaminant limits or treatment requirements were not met. At 10.3 violations per 100,000 people served, this rate is high and signals significant water quality management issues.

Consumer Guidance

Residents of Weld County should be aware that arsenic has been identified as a watershed impairment cause, and drinking-water compliance is at a C-grade level. Weld County's drinking-water compliance score is 55.2 out of 100. Long-term low-level arsenic exposure is a health concern; an NSF 58-certified reverse-osmosis filter is the most effective point-of-use option for arsenic removal. Reviewing your utility's Consumer Confidence Report will show whether treated water meets the EPA's 10 ppb MCL. The violation rate for Weld County is 10.3 per 100,000 people served. With 119 active water-quality monitoring sites in Weld County, data coverage is strong. A pipeline streamflow snapshot from the SOUTH PLATTE RIVER gauge is also available on this page.

Regional Context

Weld County has better water quality than the average county in Colorado. Its water score is 16.5 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 Weld County's water environment

Watershed Impairment Causes (EPA ATTAINS)

  • 1

    Arsenic

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

  • 2

    E. coli (bacteria)

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

  • 3

    Copper

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

Source: EPA ATTAINS · Reporting cycle 2022

Official EPA Resources for Weld County

EPA How's My Waterway

Interactive watershed health data for Weld County

EPA ECHO: Drinking Water Systems

Search water utilities and violation records for Weld County

Consumer Confidence Reports (CO)

Annual water quality reports from utilities in Colorado

Clean Water Act §303(d)

Watershed Health

Impaired Water Bodies

48.9%

92 of 188 assessed

Moderate concern

Top Impairment Causes

  • 1

    ARSENIC

  • 2

    ESCHERICHIA COLI (E. COLI)

  • 3

    COPPER

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

119

Active in the past 5 years

Measurements Recorded

51K

51,240 total readings

Most Measured

  • Nutrient
  • Physical
  • Organics, Pesticide

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

190cfs

May 14, 7:00 PM UTC

vs Long-Term Average

47%

Well below typical

Primary Streamgage

SOUTH PLATTE RIVER AT FORT LUPTON, CO.

USGS site
06721000
Drainage area
5,043 sq mi
Long-term mean
408 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 Weld 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 Weld County, Colorado?
Weld County, Colorado has a drinking-water quality grade of C with a score of 55.2/100, based on EPA SDWIS compliance data. The county has 37 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 Weld County?
Weld County has 37 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 Weld County?
EPA ATTAINS assessments under Clean Water Act §303(d) indicate 48.9% of Weld County's 188 assessed water bodies are classified as impaired (92 impaired). The top reported causes are ARSENIC, ESCHERICHIA COLI (E. COLI), COPPER. 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 Weld County?
EPA's Water Quality Portal records 51,240 measurements from 119 monitoring sites in Weld County over the past five years. The most frequently measured characteristic groups are Nutrient, Physical, Organics, Pesticide. 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 Weld County right now?
Weld County's primary USGS streamgage on the SOUTH PLATTE RIVER has a pipeline snapshot of 190 cubic feet per second — 47% of the long-term mean of 408.48 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 Weld County water compare to the Colorado average?
Weld County's SDWIS water quality score of 55.2/100 is higher than the Colorado state average of 38.7. The average water quality grade across Colorado is F, based on data from 64 counties with available SDWIS data.
Is tap water safe to drink in Weld County?
Based on EPA SDWIS data, Weld County has a water quality grade of C (55.2/100). 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 Weld County have so many water violations?
Weld County has 37 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 Weld County rank for water quality in Colorado?
Weld County ranks #16 out of 64 counties in Colorado by SDWIS water quality score (1 = best). With a score of 55.2/100, 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

Montezuma County

Colorado

C

54.6

Water score

Boulder County

Colorado

C

56.1

Water score

Jefferson County

Colorado

C

54.0

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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