LEWISTON – Drinking water exceeded federal standards for a cancer causing chemical, according to a study released by the city this week.
Water quality testing at four areas in Lewiston showed elevated levels of haloacetic acid in May, September and November of last year. The level had dropped back to safe standards, according to tests run on March 28.
The increased levels prompted the city to switch water treatment methods in March, according to David Jones, public services director.
Lewiston’s drinking water was being treated with chlorine until March. Chlorine can react with organic matter – including algae, bacteria and viruses – to create haloacetic acid. The EPA considers 60 parts of haloacetic acid in 1 billion parts of water to be a cancer risk.
Tests showed levels at 61.8 parts-per-billion in May 2005, 72 parts-per-billion in September and 62 parts-per-billion in November.
Lewiston’s new treatment method injects ammonia into the water, creating a new compound called a chloramine. The new compound is a longer lasting disinfectant that lets the city use less, reducing the amount of byproducts – including haloacetic acids, Jones said.
Lewiston began using chloraminated water in March. Haloacetic acid levels were at 52 parts-per-billion by March 28, just below EPA standards.
“We expect them to get even lower, although they will never go down to zero,” Jones said. “Although, 52 parts-per-billion is pretty close to zero.”
Jones said this is the first time the city has had elevated levels for chemical byproducts. The EPA requires them to notify water users if the average level goes beyond standards for a year. He was hoping switching to chloraminated water would reduce the haloacetic acid levels even lower by March 28.
The city is scheduled to begin mailing notices to Lewiston water users warning them of the haloacetic acid levels. Jones said the city also planned to post notice at City Hall and at the Lewiston Public Library.