Latest state-required Yorba Linda Water District report lists contaminant levels in water supply

State law requires water agencies with more than 10,000 service connections to produce a report every three years if any water quality measurements exceed specific “public health goal” levels or “maximum contaminant level” goals.

Public health goal levels are set by the state Office of Environmental Health Hazard Assessment and maximum contaminant level goals by the federal Environmental Protection Agency. They're not enforceable, and agencies aren't required to take action to meet them.

The elected directors of the Yorba Linda Water District, with some 25,000 connections in Yorba Linda and parts of Placentia, Brea and Anaheim, reviewed the 12-page 2019 report for 2016-2018 at a July 23 meeting.

According to the report, the district “is in full compliance with all state and federal drinking water standards,” and the district's “top priority is protecting public health.”

The report notes four contaminants above public health goal levels or maximum contaminant level goals – arsenic, copper, gross alpha and uranium – but all four are well below maximum contaminant levels.

Arsenic in one district well “slightly exceeds” the 10 parts per billion maximum contaminant level at 10.5 parts per billion over a three-year average. When operating, the well's water is blended with water from other wells under a plan approved by a state agency.

The result is an arsenic level of about 3.1 parts per billion, which is above the public health goal level of 0.004 parts per billion but below the enforceable maximum contaminant level.

Estimated cost to meet the public health goal level is $10.7 million, adding $35.55 to monthly bills, the report states.

Copper is not found in the district's well or imported water but usually results from a chemical reaction of the district's water with household plumbing fixtures containing copper or brass.

The district tests representative water taps for copper every three years, with 2018 results showing 90 percent of samples taken from inside homes at 0.5 milligrams per liter, above the 0.3 milligrams per liter public health goal but below the 1.3 milligrams per liter action level.

Gross alpha is the total of radionuclides (natural occurring radium, radon, uranium and thorium). The federal maximum contaminant level goal is 0, with the state level set at 15 pico-Curies per liter. The district's average is 2.6 pico-Curies per liter.

Uranium is naturally occurring or results from runoff from areas with mining operations. The public health goal level is 0.43 pico-Curies per liter, with a maximum contaminant level of 20 pico-Curies per liter. The district's average is 8.0 pico-Curies per liter.

Estimated cost to meet the public health goal level is $13.1 million, adding $43.34 to monthly bills, the report states.

The report notes: “The effectiveness of the treatment processes to provide any significant reduction in contaminant levels at already low values is uncertain.”