Lead treatments in Denver water

Peter Haynes

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Six years after Denver Water detected elevated lead in tap water at some homes, state health officials have ordered the injection of a dangerous chemical into water supplies to slow lead-pipe corrosion, but there is some push back.

The chemical, orthophosphate, would harm humans and hurt the wildlife of the South Platte River Basin in Denver, worsening algae blooms and increasing the cost of cleaning wastewater, Denver Water claims. Utility officials propose solving the problem with a different chemical to lower the acidity of drinking water, combined with increased replacement of old lead plumbing.

This disagreement has escalated into a legal fight, with Denver’s Metro Wastewater Reclamation District, Aurora and the Greenway Foundation battling the Colorado Department of Public Health and Environment in state court, potentially delaying action to deal with the problem.

No amount of lead in water is healthy, according to the U.S. Centers for Disease Control and Prevention, and even low levels can hurt children, slowing growth, impairing hearing and digestion, shortening attention spans and stunting academic achievement. CDPHE director Larry Wolk, a pediatrician, says removing lead from metro Denver tap water is an immediate top priority.

Denver Water officials have known at least since 2012 about the lead contamination, caused mostly by an estimated 58,000 lead pipelines between water mains and homes that are expensive to replace. In 2012, tap-water tests in homes showed that lead levels exceeded a federal health “action level” limit of 15 parts per billion, set in the early 1990s under the Safe Drinking Water Act. CDPHE records show 13 percent of tap-water samples taken that year contained lead at levels above the limit as high as 57 ppb.

The legal fight erupted after CDPHE officials on March 20 ordered Denver Water to inject orthophosphate. The CDPHE directed Denver Water to conduct a study. This took two years. Upon completion in 2017, CDPHE officials said they reviewed the results over six months — a study that concluded orthophosphate is the most effective method, reducing lead in tap water by 74 percent compared with a 50 percent reduction from using caustic chemicals to lower the acidity of drinking water.

CDPHE officials this week told The Denver Post they have invited Metro Wastewater, Aurora and the Greenway Foundation to forgo their legal fight in favor of working together to protect people and the environment. For months, the CDPHE has encouraged Denver Water to work with them to evaluate water treatment options, but the agency has “not seen anything in writing about moving forward,” state officials said in an email.

“If these parties continue their litigation and we are forced to fight this out in court,” the officials wrote, “we will vigorously defend our decision.”