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Resort Improvement District #1

What EPA’s and California’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
803 people
Connections
642
Water source
Surface water
Based in
Whitethorn, CA
County
Humboldt
Owner
Local government
Hardness
Varies by source
The ZIP code it serves

95589

The short answer

3 results are above the health goal. The worst: Arsenic, above the health goal. No health-based violations on file since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2007 to 2026.

Arsenic, total trihalomethanes (TTHM), haloacetic acids (HAA5), nitrate, fluoride and chromium (total): California’s own results, samples taken from Jan. 14, 2020 to June 30, 2026, with EPA’s 2012 to 2019 file for earlier years.

Uranium: EPA’s compliance monitoring file, samples taken from March 12, 2019 to Nov. 5, 2019. Newer results are in the utility’s annual water quality report.

Above the health goal3

Arsenic

Comes from the source

Above the health goal

3.7ppb

Highest yearly average, 2020 to 2025

2025: not found

Averaged by year, the highest was 3.7 ppb, in 2020: below EPA’s legal limit of 10 ppb, but above its health goal of zero. In 2025, the latest year on file, it wasn’t found in any of its six samples. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 6.3 ppb, in 2017.

What handles it

  • NSF/ANSI 58 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
  • NSF/ANSI 53 look for “Arsenic (Pentavalent)<=50 ppb Reduction”

Lead

Comes from pipes, often your own

Above the health goal

1.8ppb

90th percentile, 2024 to 2026

In the latest period, 9 in 10 homes sampled were at or below 1.8 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

0.52ppb

Highest yearly average, 2019

Averaged by year, the highest was 0.52 ppb, in 2019: below EPA’s legal limit of 30 ppb, but above its health goal of zero. Its highest single sample was 1.5 ppb. That is the only year on file.

What handles it

Below EPA’s limits4

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

52.9ppb

Highest yearly average, 2020 to 2026

2026 average: 15.5 ppb

Averaged by year, the highest was 52.9 ppb, in 2022, below EPA’s legal limit of 80 ppb. In 2026, the latest year on file, its two samples averaged 15.5 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 8.8 ppb, 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

Below EPA’s limits

29.3ppb

Highest yearly average, 2020 to 2026

2026, one sample: 24 ppb

Averaged by year, the highest was 29.3 ppb, in 2022, below EPA’s legal limit of 60 ppb. In 2026, the latest year on file, its one sample was 24 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 45 ppb, in 2019.

What handles it

No certification claim covers this compound yet.

Nitrate

Comes from the source

Below EPA’s limits

1.9ppm

Highest sample; found in 62 of 126

2026 average: 0.16 ppm

The highest sample, in 2024, was 1.9 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, its eight samples averaged 0.16 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 2.3 ppm, in 2018.

What handles it

  • NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
  • NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.18ppm

Highest yearly average, 2020 to 2025

2025 average: 0.12 ppm

Averaged by year, the highest was 0.18 ppm, in 2020, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.37 ppm. In 2025, the latest year on file, its six samples averaged 0.12 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.24 ppm, in 2014.

What handles it

One compound tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Chromium (total)

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: Arsenic (Pentavalent)<=50 ppb Reduction, Lead Reduction

    For: Arsenic, Lead

    Other certifiers’ wording: Arsenic (III) (50 ppb influent level)

  • NSF/ANSI 58

    Claims: Arsenic (Pentavalent)<=50 ppb Reduction, Lead Reduction, Uranium

    For: Arsenic, Lead, Uranium

    Other certifiers’ wording: Arsenic (Pentavalent)<=300 ppb Reduction; Arsenic (V) (300 ppb influent level)

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 reverse osmosis systems, ranked

The best water filters for lead, ranked

Hardness

Soft to very hard depending on the source, 7.5 to 280 mg/L (0.4 to 16.4 grains per gallon), across 15 sampling points, 2019 to 2025.

Hardness is calcium and magnesium. EPA sets no limit for it: it shows up as scale on fixtures and in water heaters, and as soap that won’t lather. USGS calls water above 60 mg/L moderately hard, above 120 hard and above 180 very hard.

Softeners compared, salt includedSoftener or salt-free conditioner?California water hardness, utility by utility

Violations since 2016

No health-based violations on file with EPA since 2016. There is 1 monitoring or reporting violation: a sample missed, late or not reported.

What this report can’t tell you

  • Everything else. Arsenic, total trihalomethanes (TTHM), haloacetic acids (HAA5), nitrate, fluoride and chromium (total) results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Uranium comes from EPA’s file alone, which ends in 2019. Resort Improvement District #1’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; California’s results run from Jan. 14, 2020 to June 30, 2026; EPA’s compliance samples are from March 12, 2019 to Nov. 5, 2019.

Testing your own tap

Resort Improvement District #1’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 California certifies.

The 3 labs California certifies closest to the area Resort Improvement District #1 serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Humboldt County Public Health Laboratory

    Eureka, CA · about 53 miles

    Certified for bacteria

    (707) 268-2179

  • Microbac Laboratories, Inc. - Arcata

    Arcata, CA · about 59 miles

    Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, organic chemicals, disinfection byproducts

    (707) 822-4649

  • Alpha Analytical Laboratories, Inc. - Ukiah

    Ukiah, CA · about 74 miles

    Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, organic chemicals, disinfection byproducts, radioactivity

    (707) 468-0401

All 145 certified labs for California

Sources

PWSID CA1210022. Rebuilt from EPA data on Oct. 18, 2026.

Also in Humboldt County

All California utilities

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