Denver Water is fighting a push by a global mining giant to increase by 43 times Colorado’s limit for molybdenum pollution of streams, including headwaters of the Colorado River above Denver’s drinking-water reservoir.
Freeport-McMoRan subsidiary Climax Molybdenum has asked the Colorado Department of Public Health and Environment to relax the water quality limit for molybdenum in streams used for domestic water statewide to 9,000 parts per billion from 210 ppb. It also wants the limits for waterways tapped for agricultural irrigation raised to 1,000 ppb from 160 ppb.
The change could cut water-treatment costs at the company’s open-pit Climax Mine above Leadville, where the company produced about 16 million pounds of molybdenum in 2016, down from 23 million pounds in 2015.
Climax has submitted studies the company helped fund using rats to justify raising state limits.
But Denver Water says the research isn’t sound.
“The standard proposed by Climax based on studies it completed on laboratory animals do not appear to adequately extrapolate to human health impacts,” said Tom Roode, the utility’s chief of operations and maintenance. “While the increased discharge may save costs at the mine, it has the potential to increase treatment costs at Denver Water’s treatment plants.”
Denver’s water treatment plants lack the capacity to remove molybdenum, which in trace amounts can be healthy. While data on human toxicity is limited, chronic ingestion of molybdenum can cause diarrhea, stunted growth, infertility, low birth weights and gout, and can also affect the lungs, kidneys and liver.
“Our position is that the molybdenum standard should be based on sound science quantifying human health impacts,” Roode said.
At the mine atop Fremont Pass, Climax discharges molybdenum into Tenmile Creek, which flows into Dillon Reservoir. That water moves through a tunnel under mountains to the South Platte River and then flows to Foothills and Marston treatment plant intake systems near the Strontia Springs Reservoir southwest of Denver. Denver relies on the South Platte watershed for 80 percent of the water it provides to 1.4 million people.
The Environmental Protection Agency currently does not regulate molybdenum under the federal Safe Drinking Water Act, but federal officials have considered regulating it in the future.
Climax sent a statement to CDPHE saying its proposal “is not based on any intent or need to increase molybdenum in Climax discharges, and in particular, Climax does not intend to change its mining or water treatment process in a manner that would cause an increase in the historical discharge of molybdenum into Tenmile Creek.”
CDPHE water quality staffers had not made a recommendation on the issue, to be decided by state water quality control commissioners in December. CDPHE chief Larry Wolk and water quality division director Pat Pfaltzgraff, through a spokesman, declined to discuss the issue.
State health staffers apparently have drafted recommendations for commissioners but this draft could not be made public, water quality division spokeswoman Meghan Trubee said.
Climax representatives referred queries to Freeport-McMoRan’s corporate spokesman Eric Kinneberg.
“The current Colorado Molybdenum Standards were based on inadequate studies that did not meet appropriate guidelines nor peer-review processes, but were all that were available at the time the existing regulations were established,” Kinneberg said in an email.
Silvery gray, molybdenum is found in oxidized rock and is used to harden steel. Demand increased during World War I with molybdenum put in armor plating for tanks and heavy artillery howitzer guns
Freeport-McMoRan also owns and operates the Henderson molybdenum mine near the base of Berthoud Pass in Clear Creek County and a mill in Grand County. Built in the 1970s, the Henderson mine discharges molybdenum into the west fork of Clear Creek, but that flow is treated at a plant where the Urad mine site is being reclaimed.
Climax officials had planned to close the Henderson mine and mill, which employ 320 workers, but recently with molybdenum prices rising officials announced they’ll extend operations to 2026.
The Climax Mine above Leadville opened in 1918 and closed in 1987. Freeport-McMoRan reopened it in 2012. It employs 355 workers.
The studies Climax submitted, based on feeding molybdenum hydrate to rats and concluding higher limits would be safe, were conducted in Europe by the International Molybdenum Association to help inform government regulatory agencies. Freeport-McMoRan is the world’s largest producer of molybdenum and contributed to the funding for those studies.
EPA officials overseeing CDPHE protection of water quality have been notified of the Climax proposal. EPA spokesman Rich Mylott said the agency “will be submitting comments to the water quality control commission,” but he declined to state the agency’s position.
The local authorities along Colorado River headwaters initially opposed the push to allow increased molybdenum discharges, Grand County county commissioner Rich Cimino said in an interview this week. But Climax officials asked them to reconsider.
“They asked us to relook at the scientific study they’ve done,” Cimino said. “We agreed to do that.”
Most Grand County residents are on well water, he said. “We are concerned about the environment, agriculture. We would prefer to have the molybdenum as low as possible.”
