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Climax mine seeks more lenient molybdenum standards for streams feeding Denver's water supply

CDPHE wants to determine health impacts first
Posted at 2:09 AM, Dec 01, 2017
and last updated 2017-12-01 04:26:47-05

DENVER – One of Colorado’s largest mining operations wants to discharge more molybdenum into a stream which feeds into Denver’s water supply.

The Climax mine, between Copper Mountain and Leadville, discharges into Ten Mile Creek, which flows into Dillon Reservoir.

Dillon provides more than a third of the water used by 1.4 million people served by Denver Water.

Molybdenum Standards

State health officials say molybdenum is not a “regulated contaminant.”

But there is a Colorado basic water quality standard.

The current molybdenum standard is 210 parts per billion.

Climax Molybdenum Company wants that changed to 9,000 parts per billion.

The state health department’s Water Quality Division is recommending that the Water Quality Commission not revise standards until the Agency for Toxic Substances and Disease Registry, (ATSDR) a federal public health agency, evaluates industry sponsored studies to determine a level of molybdenum that adequately protects human health.

According to documents obtained by Denver7, EPA takes the position that a “molybdenum table value standard of 10,000 parts per billion would be protective of the water supply use classification and consistent with Clean Water Act requirements.”

There is no maximum contaminant limit for molybdenum, but the HAL (Health Advisory Levels) published by the EPA Office of Drinking Water are 40 parts per billion on a lifetime basis and 80 parts per billion on a 1-day and 10-day basis.

Expensive changes

Denver Water argues that until the Human Health Advisory standard for molybdenum is changed, the Commission should not increase the molybdenum (streams) standard.

Doing so could be very expensive.

The water provider said it does not have the ability to remove molybdenum at existing water treatment plants, and that it would cost in the range of $480 to $600 million to upgrade the Foothills and Marston Water Treatment Plants to meet (HAL) Health Advisory Levels.


Residents who live and work in the Dillon Reservoir area say all the talk about molybdenum is raising more questions.

When asked what he knows about molybdenum, Jason Ward, a shift manager at a Peppino’s Pizza & Subs replied, “Absolutely nothing, can’t even spell it.”

But Ward said it’s eye-opening to learn that Climax wants to change the standard from 210 parts per billion to 9,000 ppb.

“That’s a pretty big jump,” he said.

Fishing guide Matt Weiler told Denver7 that the mine is beneficial.

“Molybdenum is used to harden steel,” he said, “the steel we use in everyday applications for our cars and boat trailers.”

But Weiler added that water quality is important too.

“As I put it, my co-workers, my trout, need clean water,” he said.

Weiler said he’s noticed a distinct lack of fish in certain steams near other mines in the area.

He said he can’t help but wonder what might happen if Climax is allowed to discharge more molybdenum into Ten Mile Creek.

“It throws that big question mark up,” he said.

Health officials believe a final toxicological profile for molybdenum may be available as early as 2018.

They say right now, “nothing has changed,” and that a final decision on Climax’s request may not be made until November of 2019.