INSIDE
District considers treatment options

By Meg Olson

A new regimen of testing the Point Roberts water supply has discovered potentially carcinogenic organic compounds at levels higher than allowed under federal clean water standards.

“We haven’t failed the standard yet but I know we will,” district manager Dan Bourks told water district commissioners at their September 9 meeting. Bourks said testing for trihalomethanes and haloacetic acids, had started in early 2004, and the district was over the maximum contaminant level for two quarters in a row.

In 1974 the federal Environmental Protection Agency (EPA) started looking at chemical compounds that appear in water as byproducts of disinfection to determine their effect on human health. Trihalomethanes and haloacetic acids are formed when chlorine used for disinfection interacts with natural organic matter. Other chemical disinfectants, like ozone, produce different byproducts that may also impact human health. “This isn’t uncommon in an unfiltered surface source,” Bourks explained, adding filtration to remove the organic matter, such as algae and decaying plant material, would dramatically reduce the problem.
After 20 years researching the effect of disinfection byproducts on laboratory animals EPA publications stated while the agency could not “conclude there is a causal link between exposure to chlorinated surface water and cancer, these studies have suggested an association, albeit small, between bladder, rectal, and colon cancer and exposure to chlorinated surface water.” As a result in 1998 the agency put limits on disinfection products in drinking water. “In sum, EPA believes the weight-of-evidence presented by the available epidemiological studies on chlorinated drinking water and toxicological studies on individual disinfection byproducts support a potential hazard concern and warrant regulatory action at this time,” the rules state. The EPA website warns that “some people who drink water containing trihalomethanes in excess of EPA’s standard over many years may experience problems with their liver, kidneys, or central nervous systems, and may have an increased risk of getting cancer,” and link haloacetic acids to increased cancer risk.

Small water systems like Point Roberts were required to start monitoring disinfection byproducts in December 2003 and reporting their results to the state department of health (DOH), which enforces EPA regulations. “I’ll be working with the department of health,” Bourks said. “We’ll need to take measures to reduce levels. I don’t know what we can do in the short term without filtering it.”

In a letter to Bourks at the end of July DOH engineer Jolyn Leslie suggested disinfection improvements now underway would likely help to reduce the level of disinfection byproducts by keeping the water moving more, which lowers the level of organic matter that would react with the chlorine. “We’re working with them to better understand the system and make some changes to bring those numbers down,” she said.
Leslie had also suggested monitoring incoming levels from Canada to compare with the local water supply, which is rechlorinated by state law. Bourks said incoming water was “right on the edge of the standard” while samples that were chlorinated again on the Point exceeded it. “We’ll be doing more samples and running an analysis of the system to see where we can make changes,” he said.

Leslie said if the district did not get the levels of disinfection byproducts under the maximum allowable contaminant level by the end of the year, they would be in violation of state and federal drinking water standards and would need to notify their customers and develop a plan to remedy the situation, which she added the district was already working on.

Commissioner Sue Johnson asked if concerned water district customers could remove the disinfection byproducts from their water using a home charcoal filtration unit, such as a Brita filter. Bourks said they could and he would be researching other home filtration systems water users could rely on until the district and their supplier, the Greater Vancouver Regional District, add filtration to their treatment systems. “A solution for us would be an activated charcoal pre-reservoir filter,” suggested commissioner Arthur Wilkowski.

Johnson pointed out that it was the tests that were new, not the presence of the disinfection byproducts in the water. “We might have had it for 15 years,” she said. Bourks agreed and pointed out that at low levels such as were present in the Point Roberts water supply, there was no conclusive evidence of ill effects in laboratory animals. “You have to be ingesting large quantities,” he said. Epidemiological studies continue to try and quantify the cumulative effect, if any, of low levels on humans.

“It’s not a calamity. The system is evolving and regulations are changing,” Wilkowski said. “It’s not cause for alarm but part of continuing efforts to make our water cleaner and cleaner, safer and safer.”