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Del Oro Traver District

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
657 people
Connections
199
Water source
Groundwater
Based in
Chico, CA
County
Tulare
Owner
Private
Hardness
Very hard
The ZIP code it serves

93673

The short answer

1 result is above EPA’s legal limit, 1 more is above the limit’s level with no violation recorded, and 1 more is above the health goal. The worst: Nitrate, above the legal limit. 4 health-based violations since 2016.

What handles it

What was found

Nitrate, arsenic, fluoride, total trihalomethanes (TTHM), chromium (total) and haloacetic acids (HAA5): California’s own results, samples taken from Feb. 10, 2020 to June 2, 2026, with EPA’s 2012 to 2019 file for earlier years.

Uranium: EPA’s compliance monitoring file, samples taken from April 3, 2013 to May 6, 2015. Newer results are in the utility’s annual water quality report.

Above the legal limit1

Nitrate

Comes from the source

Above the legal limit

14.4ppm

Highest sample; found in 130 of 130

2026 average: 10.4 ppm

From 2023 to 2026, at least 25 samples were above EPA’s legal limit of 10 ppm, the highest 14.4 ppm in 2025. The next sample at the same point, within 30 days, kept the average above the limit for 16; two came back under and seven have no follow-up sample on file within 30 days. In 2026, the latest year on file, its 23 samples averaged 10.4 ppm. EPA recorded violations for nitrate at this utility in 2023 and 2024. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 24.3 ppm, in 2017.

What handles it

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

Above the limit’s level, no violation recorded1

Uranium

Comes from the source

Above the limit’s level, no violation

71.5ppb

Highest yearly average, 2013 to 2015

Averaged by year, the highest was 71.5 ppb, in 2015, about 2.4 times EPA’s legal limit of 30 ppb. That was also the latest year on file. EPA judges this limit on running averages at each sampling point, and recorded no violation for uranium at this utility from 2012 to 2019. Results like these with no violation often include water sampled before treatment or blending; the utility’s annual report says what reaches the tap.

What handles it

Above the health goal1

Arsenic

Comes from the source

Above the health goal

0.52ppb

Highest yearly average, 2022 to 2025

Averaged by year, the highest was 0.52 ppb, in 2025: below EPA’s legal limit of 10 ppb, but above its health goal of zero. Its highest single sample was 2.1 ppb. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 2.4 ppb, in 2016.

What handles it

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

Below EPA’s limits2

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.15ppm

Highest yearly average, 2022 to 2025

Averaged by year, the highest was 0.15 ppm, in 2025, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 0.17 ppm. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.13 ppm, in 2013.

What handles it

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

3.0ppb

Highest yearly average, 2023 to 2026

Averaged by year, the highest was 3.0 ppb, in 2026, below EPA’s legal limit of 80 ppb. Its highest single sample was 8.2 ppb. That was also the latest year on file.

What handles it

  • NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
  • NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Chromium (total)
  • Haloacetic acids (HAA5)
  • Lead

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: Nitrate/Nitrite (30 ppm challenge), Arsenic (Pentavalent)<=50 ppb Reduction

    For: Nitrate, Arsenic

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

  • NSF/ANSI 58

    Claims: Nitrate/Nitrite Reduction, Uranium, Arsenic (Pentavalent)<=50 ppb Reduction

    For: Nitrate, Uranium, Arsenic

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

At the tap, or for the whole house?

These come with the water itself, so a whole-house system certified for the same claims treats every tap and shower. A filter at the tap treats drinking water for much less. 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

Hardness

Very hard, typically 244 mg/L (14.2 grains per gallon), across 2 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 at 14.2 grains per gallon, salt includedSoftener or salt-free conditioner?California water hardness, utility by utility

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleAug. 1, 2024 to Aug. 31, 202411 MG/LArchived
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleJune 1, 2024 to June 30, 202413 MG/LArchived
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleFeb. 1, 2024 to Feb. 29, 202410.5 MG/LArchived
NitrateA sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single SampleNov. 1, 2023 to Nov. 30, 202311.1 MG/LArchived
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record.

What this report can’t tell you

  • Everything else. Nitrate, arsenic, fluoride, total trihalomethanes (TTHM), chromium (total) and haloacetic acids (HAA5) 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. Del Oro Traver District’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 Feb. 10, 2020 to June 2, 2026; EPA’s compliance samples are from April 3, 2013 to May 6, 2015.

Testing your own tap

Del Oro Traver District’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 Del Oro Traver District serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Fruit Growers Laboratory, Inc.

    Visalia, CA · about 9 miles

    Certified for bacteria

    (559) 734-9473

  • Sierra Dairy Laboratory

    Tulare, CA · about 18 miles

    Certified for bacteria

    (559) 686-2070

  • BSK Associates

    Fresno, CA · about 23 miles

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

    (559) 497-2888

All 145 certified labs for California

Sources

PWSID CA5400553. Rebuilt from EPA data on Oct. 18, 2026.

Also in Tulare County

All California utilities

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