Just a little toxic

Despite water treatment, Boulder Creek tests above standards for arsenic levels

Boulder Creek
Photo by Cecelia Gilboy

When scientists tested arsenic levels at 38 sites along Boulder Creek over six months in 2011, every sample contained arsenic levels at least 10 times above the applicable state standard. Low levels of arsenic are unavoidable in Boulder Creek and other Colorado drinking water sources, city and state officials say, and trying to reduce current arsenic levels to meet state standards for drinking and fishing water would be too costly.

Arsenic is a naturally occurring element that can be carried into water by natural processes, like erosion, and human activities, like mining and agriculture.

“Arsenic is a carcinogen at low levels,” says Andrew Ross, groundwater quality coordinator at the Water Quality Control Division at the Colorado Department of Public Health and Environment. “At high levels, it’s an acute poison.”

In April, the Colorado Water Quality Commission will hold a hearing on relaxing arsenic standards for 13 rivers and river basins around the state. The commission already adopted a temporary modification, effective Dec. 31, for one segment of Boulder Creek, located just downstream of the city.

“Segment Nine is designated as drinking water supply,” says Bret Linenfelser, water quality and environmental services coordinator for the City of Boulder. That segment’s arsenic standard is set — until 2021 — at “current condition” instead of a numerical value.

Segment Nine became a problem when the 75th Street Wastewater Treatment Facility needed to renew its permit. Its effluent contained arsenic at levels over 18 times higher than the applicable arsenic standard — on its good days. The city couldn’t hope to comply with the standard in time, so they proposed the “temporary modification” to the water quality commission.

The 75th Street water treatment facility achieves “minimal” arsenic removal, according to Linenfelser’s testimony to the water quality commission in support of the temporary modification. But the minute water leaves the facility, it begins accumulating arsenic again. A couple miles downstream, tests show even higher arsenic levels than those found when the water entered the facility.

“Yes we do see the level of arsenic increase below the city of Boulder wastewater treatment facility [WWTF],” Linenfelser clarified in a follow-up email to Boulder Weekly. “Although we do not know the cause for sure we assume it is from runoff from lands downstream of the WWTF (which is mostly open space and agriculture).”

“We know there’s elevated arsenic in the Front Range, which we think came from pesticide levels,” Ross says.

Agriculture isn’t the only industry contributing arsenic to waterways. Ten large corporations have Industrial Wastewater Discharge Permits issued by the City of Boulder. When Linenfelser and his colleagues tested samples of effluent from six of the companies allowed to discharge into Boulder Creek, a pharmaceutical company’s effluent had a markedly higher arsenic content than any other dischargers — about 154 times higher than the applicable state arsenic standard. That company is one of four pharmaceutical companies that have permits to discharge their wastewater into Boulder Creek.

“Our opinion is that it doesn’t play a role,” Linenfelser says. “Their concentration may be elevated compared to others, but the amount of flow from one particular industry is a very small portion.”

“Our picture of the arsenic in Colorado is pretty limited,” Ross says. “I don’t think anything’s increasing, but that’s just based on what we know today.”

Asked if the current levels are safe, Ross responds, “I honestly don’t know.”

The current standard for drinking- and fishing-water was calculated to result in cancer to one in 1 million people of average weight who drink average amounts of water. When meeting this standard emerged as a statewide problem, a workgroup was created.

“Boulder believes that the workgroup process is the most productive avenue,” reads the city’s response to questions from the commission about their plan to eliminate the need for a temporary modification. But the workgroup effort has been slow.

“It was delayed because there were quite a bit of different opinions about how we should move forward,” says Sarah Johnson, standards unit manager at the Colorado Water Quality Division. “Dischargers and entities who have large sewage treatment plants, like the City of Boulder, have one set of issues, and construction dewatering projects have a different set of concerns.”

The water quality division’s new proposal promises that “no effluent limitation shall require an ‘end-of-pipe’ discharge level more restrictive than” three parts per billion, which is 150 time greater than the state water and fish standard, though still less than the national drinking water standard, which is 10 parts per billion. But dis chargers with permits by June 2013, like the pharmaceutical company whose effluent was found to contain arsenic exceeding that level, will have “current condition” as their standard until 2021.

Does the standard have to be changed? When an engineering consulting firm was hired to provide the city with an independent evaluation, their memo concluded that the current standard “may be achievable with the use of multiple treatment processes.”

“I think it’s possible to adopt new technologies,” Linenfelser says, but “it would cost multiple millions of dollars to even try.”

But it’s unlikely Colorado waters will be treated with any of those new technologies.

“I don’t think so,” Johnson says. “Our proposal is to make things more lenient.”

Respond: letters@boulderweekly.com