For the third time in three years, a ruptured underground pipe discharged contaminated water from the defunct Cotter Corp. uranium mill near Cañon City.

But the spill, which took place Nov. 5, was five to 10 times larger than the previous discharges.

Warren Smith, a spokesman for the Colorado Department of Public Health and Environment, said the company reported 4,000 to 9,000 gallons of water tainted with uranium and molybdenum spilled onto the ground. Spills in November 2010 and 2012 were under 1,000 gallons, incident reports show.

None of the contamination from the spills escaped the property, and the on-site collection system worked as designed, Smith said.

“There was nothing negligent about this. It was just a leaky pipe,” Smith said. “Because no water left the property, no member of the public was exposed, and therefore there was no public health risk.”

However, Travis Stills, a lawyer for Colorado Citizens Against Toxic Waste, said that’s not good enough.

“What we’re seeing out there is kind of a routine setup where the first serious freeze every fall, there’s a spill,” Stills said. “The CDPHE says, ‘No problem,’ then the same thing happens a year later. It’s an indifference to the fact that groundwater is very important to the use of people in that area. It’s used for orchards, drinking water, ranching — the list goes on.”

Water from the Cotter site is collected in lined containment pits where it evaporates, leaving a toxic sludge that includes uranium and molybdenum. Smith said that since the pipe was buried, cold weather may not have been a factor in the rupture.

Representatives from Cotter did not return phone calls for comment. The company excavated and repaired the broken pipe the day after the Nov. 5 spill, according to the incident report.

Cañon City councilwoman Pat Freda — who represents the Lincoln Park neighborhood, which is less than a mile from the Cotter site — said she finds the fact that spills occurred in three of the past four years disturbing.

“As I understand it, this equipment is pretty old and decrepit and should be completely reworked,” she said. ” I think that when you have this pattern of release, … this tells you something is not right out there and needs to be taken very, very seriously.”

The Cold War-era uranium-processing mill operated until 1979. The property was declared a Superfund disaster site in 1984.

A local citizens advisory group, of which Freda is a member, was recently formed to work with the Environmental Protection Agency and other stakeholders to formulate a plan on how best to clean up the site.

“To me that’s what this all comes down to: This needs to be fixed once and for all,” Freda said.

Austin Briggs: 303-954-1729, abriggs@denverpost.com and twitter.com/ austinbriggs10