By Shawn Raymundo
Councilmembers voted Tuesday, Sept. 3, to accept the city’s latest public health report on San Juan’s drinking water, which was found to contain certain contaminants while still meeting state and federal government standards.
The state-mandated Domestic Water Public Health Goals Report presented to the council as part of a public hearing concluded that while some of city’s drinking water was found to contain constituents like arsenic, coliform bacteria and uranium at various times in the past few years, their levels were significantly below maximum allowable limits and didn’t pose a public health risk.
Based on those findings, the city is not recommending the implementation of any additional treatment process options as such endeavors would be costly to San Juan’s ratepayers who could be looking at an increase of $35 to $70 in their monthly water bills, according to the city.
Cities throughout the state are required to regularly test their drinking water. Agencies that detect one or more contaminants that exceed the Public Health Goal (PHG) are required to submit a report every three years to the California State Water Resources Control Board.
According to the state’s Office of Environmental Health Hazard Assessment, the PHG “is the level of a chemical contaminant in drinking water that does not pose a significant risk to health.”
The U.S. EPA’s maximum standards for how much of a contaminant is allowed in drinking water is called the Maximum Contaminant Level Goals.
According to the city’s findings, 0.0023 milligrams per liter of arsenic was detected in water imported from the Metropolitan Water District of Southern California (MET) in 2015, exceeding the PHG for arsenic, which is set at 0.000004 milligrams per liter. The maximum allowable level of arsenic is 0.01 milligrams per liter.
“Arsenic is most commonly found in water sources as a result of natural leaching from soils,” the city states. “Arsenic consumed over a long period of time above the Maximum Contaminant Level may cause cancer and other noncancerous effects on humans, including cardiovascular, immunological, and neurological effects.
From 2014 to 2018, uranium was detected in various water supplies including MET, the Northwest Open Space and the Groundwater Recovery Plant. The PGH for uranium is .43 picocuries per liter while its Maximum Containment Level is 20 picocuries per liter.
A picocurie is a measurement of radioactivity.
Water from MET contained an average of 1.8 picocuries per liter and ranged from 3 picocuries per liter to non-detection. At the open space, the city detected an average of 4.26 picocuries per liter, ranging from 4.5 to 4.2 picocuries per liter. The city detected an average of 1.2 picocuries at the recovery plant and ranged from 2 picocuries per liter to non-detection.
“Uranium occurs naturally in the ground and dissolves into groundwater supplies,” the city states. “The natural radioactivity results from well water passing through deposits of naturally occurring radioactive materials. Uranium consumed over a long period of time above the Maximum Contaminant Level may cause cancer.”
As for coliform bacteria, the city found such contaminants between 2014 and 2018. Coliform bacteria has a PHG of 0% positive samples per month and a Maximum Contaminant Level of 5% positive samples of all samples per month.
From 2014 to 2018, 55 of the city’s 60 monthly sample collections tested positive for coliform bacteria. The highest percentage found in 2014 and 18 were 2% and 1.9%, respectively. The city’s monthly test sample for September 2016 revealed 16.7 % coliform bacteria, prompting a mandated public notification process.
“So the remedy for that was that we had to report it to the citizenry, we had to mail out a report to everybody, we had to flush the system and the following day we got results. We resolved the issue,” Public Works & Utilities Director Steve May explained at the council meeting. “We’re not sure what caused that … but it was resolved within a 24-hour period and we didn’t have to do a boil-water period or anything like that.”
According to the city, coliform bacteria is not generally considered harmful, but when samples test positive for it, an investigation is needed to find the cause of the potential problem and follow up sampling must done.
“It is not at all unusual for a system to have an occasional positive sample,” the city states. “It is difficult, if not impossible, to ensure that a system will never get a positive sample.”
The city said it’s already taken steps the Division of Drinking Water prescribes to treat coliform bacteria. To take additional steps to remove arsenic, the city could treat the water with an ion exchange, which it says is the lowest cost alternative option, or with reverse osmosis.
The cost for an ion exchange treatment for arsenic would cost the city approximately $5 million a year while the reverse osmosis system would cost roughly $10 million a year. Such practices to treat uranium, the city notes, is already being done at the MET’s treatment plant and city’s groundwater plant.
“Additional treatment options would add between $35 and $70 per month to the average household water bill,” the city states. “The cost of treating the City’s water to provide any significant reduction of these already low values, with no evidence that further treatment would provide any public health benefits, would be impractical and infeasible.”
Shawn Raymundo is the city editor for The Capistrano Dispatch. He graduated from Arizona State University with a bachelor’s degree in Global Studies. Before joining Picket Fence Media, he worked as the government accountability reporter for the Pacific Daily News in the U.S. territory of Guam. Follow him on Twitter @ShawnzyTsunami and follow The Dispatch @CapoDispatch.