Climax asks for third extension on molybdenum
A giant open-pit mine that discharges molybdenum at levels up to 14 times higher than a state limit into a mountain creek above Denver’s drinking water supply reservoir is asking for a third extension of a “temporary” lifting of that health limit.
Nobody’s objecting. Denver Water says by the time water reaches 1.4 million residents, molybdenum contamination doesn’t exceed a federal health advisory level.
If granted next week by Colorado Department of Public Health and Environment water quality commissioners, the extension through 2020 would give Climax Molybdenum greater flexibility above Dillon Reservoir at the Climax Mine on Fremont Pass. Molybdenum is used to harden steel and for petroleum-industry lubricants.
Climax also is lobbying the CDPHE to change the statewide limit for molybdenum pollution of streams, which would ease the its wastewater-cleaning burden. Climax has submitted industry-backed studies, not yet peer-reviewed, supporting a relaxation of Colorado’s limits to 9,000 parts per billion (ppb) from 210 ppb for streams used to supply drinking water and to 1,000 ppb from 160 ppb for streams used for irrigating pastures and food crops.
This tussle over molybdenum pollution reflects widening challenges governments face in protecting
Pollution reduced by dilution
Tenmile Creek carries water contaminated with molybdenum down from the Climax Mine into Denver’s drinking water supply in Dillon Reservoir. State health officials say they’re aware of molybdenum levels as high as 3,000 parts per billion, 14 times higher than a state limit that they’ve suspended “temporarily” since 2014. and the environment against water contaminants that aren’t regulated — yet which scientists have found may be harmful. Among these are the perfluorinated chemicals from firefighting foam that have poisoned groundwater south of Colorado Springs and at dozens of other sites nationwide.
The Environmental Protection Agency has set unenforceable health advisory levels for some unregulated contaminants, including a 40 ppb limit for molybdenum (a concentration in drinking water “not expected to cause any adverse non-carcinogenic effects for a lifetime of exposure,”) in addition to drinking wacomment. ter regulations covering more than 90 contaminants such as lead. There’s no federal drinking water regulation for molybdenum.
The EPA must at least identify and list unregulated contaminants.
The U.S. Agency for Toxic Substances and Disease Registry (ATSDR) has determined that ingesting no more than 45 micrograms of molybdenum a day is OK for adults but that most American adults ingest 76 to 109 micrograms. Longterm exposure of rats and mice to molybdenum dust has been shown to cause damage to the nasal cavity and lungs. Animal studies also found molybdenum at high levels can impair repeople production, the kidneys and lungs. However, U.S. authorities haven’t classified molybdenum as a carcinogen.
For Climax, a subsidiary of the $46 billion global mining company FreeportMcMoRan, removing all molybdenum from wastewater could add hundreds of million of dollars in costs for an operation that employs about 400 workers.
By relaxing limits temporarily, CDPHE officials already have allowed elevated molybdenum pollution. “The (water quality control) division is aware of molybdenum levels in Tenmile Creek that range from below detection limits to nearly 3,000 ppb,” agency spokeswoman Meghan Trubee said in a written response to emailed queries.
These spikes could continue.
CDPHE officials did not raise any health concerns.
A Freeport-McMoRan spokesman on Wednesday didn’t respond to queries.
Denver Water opposes the request to weaken Colorado’s limit statewide, but would accept a another extension of a temporary modification for the area around the mine, utility spokeswoman Stacy Chesney said in an email.
“We have not seen numbers up at 40 ppb. Based on the last 10 years of data at our facilities and within our water distribution system, the concentrations are well below the health advisory levels,” Chesney wrote. Typically, tap water in Denver homes contains molybdenum at levels less than 5 ppb, she wrote.
Giving Climax an extension to comply with Colorado’s 210 ppb limit also would mean agricultural water users and towns such as Frisco, which sometimes draws water from wells along the Tenmile Creek, could face increased molybdenum pollution.
Yet a coalition of mountain water users, in documents submitted to the CDPHE, does not oppose extending a suspension of the state limit — as long as “there are assurances that Climax is working on trying to address the observed spikes in molybdenum experienced in Tenmile Creek” over the next few years.
“The temporary modification would allow existing conditions, so periodic spikes up to 2,000 ppb,” said attorney Steve Bushong, a former aquatic scientist representing some of the downstream communities.
“The water is not directly used for drinking water without significant dilution, except for any domestic wells and Frisco’s diversion points,” Bushong said. “Even if we did not accept the temporary modification, Climax would get time to come into compliance. Most of the stakeholders have had a good relationship with Climax, so that weighs into it, too. In short, everyone wants the right molybdenum standard long-term, while recognizing it might take a while to get there. Meanwhile, we want Climax using the delay to try to fix the spikes.”
Frisco’s attorney didn’t respond to requests for The state molybdenum pollution limit of 210 ppb is based on studies done elsewhere decades ago. The CDPHE and EPA haven’t conducted their own studies. The industry studies involved feeding molybdenum hydrate to rats and concluded higher limits would be safe for people. These were done in Europe by the International Molybdenum Association. Freeport-McMoRan helped fund those studies.
CDPHE water commissioners in 2014 granted Climax Molybdenum a “temporary modification” of the state limit after the Climax Mine reopened following a 25-year closure. The commissioners granted extensions in 2015 and 2017 through 2018.
EPA officials recently indicated their agency would support weakening the state limit to a level as high as 11,000 ppb. Initially, CDPHE staff scientists opposed the push to weaken the 210 ppb statewide limit.
Denver Water’s treatment plants cannot remove molybdenum. Changing the state limit to allow molybdenum pollution at 9,000 ppb would cost utility ratepayers up to $600 million for expansion of a treatment plant, utility officials have said.
State officials rescheduled a December molybdenum hearing for 2019, to give more time for the industry-financed studies to move through a peer-review process and for the ATSDR to determine how much is too much for people.