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City of Monroe

What EPA’s and CDC’s records show in this utility’s water: nitrate, arsenic and other regulated chemicals; lead and copper; and violations since 2016, with the certification that handles each result.

Serves
723 people
Connections
343
Water source
Surface water
Based in
Harrisburg, OR
County
Benton
Owner
Local government
The ZIP code it serves

97456

The short answer

2 results are above EPA’s legal limit, and 1 more is above the health goal. The worst: Total trihalomethanes (TTHM), above the legal limit. 27 health-based violations since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2017 to 2025.

Total trihalomethanes (TTHM), haloacetic acids (HAA5), nitrate and arsenic: Oregon’s yearly averages per water system, as CDC’s Environmental Public Health Tracking Network publishes them, 2020 to 2023, with EPA’s 2012 to 2019 file for earlier years.

Chromium (total), fluoride and uranium: EPA’s compliance monitoring file, samples taken from July 5, 2012 to March 13, 2019. Newer results are in the utility’s annual water quality report.

Above the legal limit2

Total trihalomethanes (TTHM)

Forms or is added in treatment

Above the legal limit

98.3ppb

Highest yearly average, 2020 to 2023

2023 average: 60.4 ppb

Averaged by year, the highest was 98.3 ppb, in 2021, above EPA’s legal limit of 80 ppb. In 2023, the latest year on file, it averaged 60.4 ppb. EPA recorded violations for total trihalomethanes (TTHM) at this utility in 2020, 2021, 2022, 2025 and 2026. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 84.8 ppb, in 2019, and EPA recorded a violation in 2019.

What handles it

  • NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
  • NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”

Haloacetic acids (HAA5)

Forms or is added in treatment

Above the legal limit

57.9ppb

Highest yearly average, 2020 to 2023

2023 average: 21 ppb

Averaged by year, the highest was 57.9 ppb, in 2020, below EPA’s legal limit of 60 ppb. In 2023, the latest year on file, it averaged 21 ppb. EPA judges this limit at each sampling point, and recorded violations for haloacetic acids (HAA5) at this utility in 2020, 2021 and 2022. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 53.1 ppb, in 2019.

What handles it

No certification claim covers this compound yet.

Above the health goal1

Lead

Comes from pipes, often your own

Above the health goal

1.5ppb

90th percentile, 2023 to 2025

In the latest period, 9 in 10 homes sampled were at or below 1.5 ppb, below EPA’s action level of 15 ppb. The action level drops to 10 ppb on Nov. 1, 2027. EPA’s health goal for lead is zero.

What handles it

Below EPA’s limits1

Nitrate

Comes from the source

Below EPA’s limits

2.0ppm

Highest yearly average, 2020 to 2023

2023: not found

Averaged by year, the highest was 2.0 ppm, in 2022, below EPA’s legal limit of 10 ppm. In 2023, the latest year on file, it wasn’t found.

What handles it

  • NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
  • NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”
4 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Arsenic
  • Chromium (total)
  • Fluoride
  • Uranium

What handles it

A certification covers specific claims, not a whole standard. Look for these claims on the certifier’s listing, not the box. Wording varies a little: NSF writes “Lead Reduction,” WQA just “Lead.”

  • NSF/ANSI 53

    Claims: Trihalomethanes (TTHM) Reduction, Lead Reduction

    For: Total trihalomethanes (TTHM), Lead

    Other certifiers’ wording: VOC Reduction

  • NSF/ANSI 58

    Claims: Trihalomethanes (TTHM) Reduction, Lead Reduction

    For: Total trihalomethanes (TTHM), Lead

At the tap, or for the whole house?

Lead and copper usually come from pipes and fixtures inside or near your home. A whole-house system sits where water enters, so it cannot catch what your own plumbing adds after it. For those, the filter that counts is the one at the tap. How whole-house systems compare.

Filters with those claims on a certifier’s listing

Disclosure: TapBuff earns a commission if you buy through some links on this page. It does not change which standard or filter we name. As an Amazon Associate, TapBuff earns from qualifying purchases. How TapBuff makes money

Compare five-year costs

The best water filters for lead, ranked

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2026 to June 30, 20260.093 MG/LArchived
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2026 to March 31, 20260.098 MG/LArchived
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2025 to Dec. 31, 20250.096 MG/LArchived
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2025 to Sept. 30, 20250.084 MG/LArchived
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2025 to June 30, 20250.081 MG/LArchived
Total Haloacetic Acids (HAA5)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2022 to Dec. 31, 20220.061 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2022 to Sept. 30, 20220.088 MG/LResolved
Total Haloacetic Acids (HAA5)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2022 to Sept. 30, 20220.07 MG/LResolved
Total Haloacetic Acids (HAA5)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2022 to June 30, 20220.07 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2022 to June 30, 20220.092 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2022 to March 31, 20220.095 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2022 to March 31, 20220.099 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2021 to Dec. 31, 20210.1 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2021 to Sept. 30, 20210.09 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2021 to Sept. 30, 20210.096 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2021 to June 30, 20210.1 MG/LResolved
Total Haloacetic Acids (HAA5)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2021 to June 30, 20210.066 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2021 to June 30, 20210.095 MG/LResolved
Total Haloacetic Acids (HAA5)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2021 to March 31, 20210.063 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2021 to March 31, 20210.11 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2020 to Dec. 31, 20200.097 MG/LResolved
Total Haloacetic Acids (HAA5)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2020 to Dec. 31, 20200.063 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2020 to Sept. 30, 20200.094 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2020 to June 30, 20200.083 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2020 to March 31, 20200.089 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2019 to Dec. 31, 20190.086 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2019 to Sept. 30, 20190.081 MG/LResolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 53 monitoring or reporting violations not shown.

What this report can’t tell you

  • Everything else. Total trihalomethanes (TTHM), haloacetic acids (HAA5), nitrate and arsenic results here are Oregon’s yearly averages as CDC publishes them, from 2020 on, with EPA’s national file for 2012 to 2019. Chromium (total), fluoride and uranium come from EPA’s file alone, which ends in 2019. City of Monroe’s own annual report, which it must send you every year, has newer results for those and the contaminants this page does not show.

  • Your own plumbing. Lead results are the 90th percentile across homes the utility samples. Your home’s service line, solder and fixtures decide yours. A certified lab test is the only way to know.

  • What it means for your health. This page reports what the records show and EPA’s limits and goals; it is not medical advice. If you are worried about a health effect, talk to a doctor or your local health department.

  • Anything after the latest data. SDWIS data is from 2026 Q3; UCMR 5 didn’t sample this utility; CDC’s yearly averages for Oregon cover 2020 to 2023; EPA’s compliance samples are from July 5, 2012 to March 13, 2019.

Testing your own tap

City of Monroe’s results are for the water it sends out. What your own service line, solder and fixtures add shows up only in a test of your tap, by a lab Oregon certifies.

The 3 labs Oregon certifies closest to the area City of Monroe serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Pacific Water Analytics

    Eugene, OR · about 21 miles

    Certified for bacteria

    (541) 321-6698

  • Eurofins Corvallis

    Corvallis, OR · about 22 miles

    Certified for bacteria, nitrate

    (360) 757-1400

  • Analytical Laboratory Group

    Eugene, OR · about 23 miles

    Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics

    (541) 485-8404

Oregon State University Extension Well Water Program: Nitrate screening of well water at many of its groundwater education events. The screening is free. Water Testing Guidance for Private Wells, OSU Well Water Program.

All 91 certified labs for Oregon

Sources

PWSID OR4100540. Rebuilt from EPA data on Oct. 18, 2026.

Also in Benton County

All Oregon utilities

What to do next