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Town of Larkspur

What EPA’s and Colorado’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
275 people
Connections
109
Water source
Groundwater
Based in
Larkspur, CO
County
Douglas
Owner
Local government
The ZIP code it serves

80118

The short answer

2 results are above the health goal. The worst: Lead, above the health goal. 8 health-based violations since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2020 to 2026.

Uranium, fluoride, total trihalomethanes (TTHM), chromium (total), arsenic, haloacetic acids (HAA5) and nitrate: Colorado’s own results, samples taken from March 11, 2020 to Aug. 3, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the health goal2

Lead

Comes from pipes, often your own

Above the health goal

0.5ppb

90th percentile, 2026

In the latest period, 9 in 10 homes sampled were at or below 0.5 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

Uranium

Comes from the source

Above the health goal

0.78ppb

Highest yearly average, 2020 to 2023

2023 average: 0.5 ppb

Averaged by year, the highest was 0.78 ppb, in 2021: below EPA’s legal limit of 30 ppb, but above its health goal of zero. Its highest single sample was 2.0 ppb. In 2023, the latest year on file, its four samples averaged 0.5 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 1.6 ppb, in 2012.

What handles it

Below EPA’s limits3

Fluoride

Forms or is added in treatment

Below EPA’s limits

1.2ppm

Highest yearly average, 2020 to 2025

2025, one sample: 1.2 ppm

Averaged by year, the highest was 1.2 ppm, in 2020, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 1.3 ppm. In 2025, the latest year on file, its one sample was 1.2 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 1.2 ppm, in 2017.

What handles it

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

5.0ppb

Highest yearly average, 2020 to 2026

Averaged by year, the highest was 5.0 ppb, in 2026, below EPA’s legal limit of 80 ppb. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 6.1 ppb, in 2015.

What handles it

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

Chromium (total)

Comes from the source

Below EPA’s limits

2.0ppb

Highest yearly average, 2020 to 2025

Averaged by year, the highest was 2.0 ppb, in 2025, below EPA’s legal limit of 100 ppb. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.5 ppb, in 2019.

What handles it

3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Arsenic
  • Haloacetic acids (HAA5)
  • Nitrate

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.”

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
Combined Radium (-226 and -228)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2023 to Dec. 31, 20236.0 PCI/LResolved
Combined Radium (-226 and -228)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2023 to Sept. 30, 20235.9 PCI/LResolved
Combined Radium (-226 and -228)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2023 to June 30, 20236.6 PCI/LResolved
Combined Radium (-226 and -228)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2023 to March 31, 20236.3 PCI/LResolved
Combined Radium (-226 and -228)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2019 to March 31, 20197.0 PCI/LResolved
Combined Radium (-226 and -228)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2018 to Dec. 31, 20186.6 PCI/LResolved
Combined Radium (-226 and -228)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2018 to Sept. 30, 20186.8 PCI/LResolved
Combined Radium (-226 and -228)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2018 to June 30, 20186.8 PCI/LResolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 32 monitoring or reporting violations not shown.

What this report can’t tell you

  • Everything else. Uranium, fluoride, total trihalomethanes (TTHM), chromium (total), arsenic, haloacetic acids (HAA5) and nitrate results here are Colorado’s own from 2020 on, with EPA’s national file for 2012 to 2019. Town of Larkspur’s own annual report, which it must send you every year, has 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; Colorado’s results run from March 11, 2020 to Aug. 3, 2026.

Testing your own tap

Town of Larkspur’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 Colorado certifies.

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

  • El Paso County Health Department

    Colorado Springs, CO · about 22 miles

    Certified for bacteria, nitrate, minerals and other inorganics

  • Colorado Department of Health & Environment

    Denver, CO · about 36 miles

    Certified for bacteria

  • SGS North America, Inc. - Denver

    Denver, CO · about 41 miles

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

All 54 certified labs for Colorado

Sources

PWSID CO0118030. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Douglas County

All Colorado utilities

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