Climax mine can now release higher levels of molybdenum into local water sources
Colorado Water Quality Control Commission raises standards following Climax mine request; new standards should not pose health risk
Hugh Carey/The Colorado Sun
This summer, the Colorado Water Quality Control Commission voted to double the limit of molybdenum Climax mine is allowed to release into local water sources. The new standards go into effect next week.
What has changed about the standards?
The Colorado Water Quality Control Commission, a body of governor-appointed representatives that sets water quality standards for the state, ruled to adopt a water quality standards change that revised the molybdenum “table value standard” (the amount of molybdenum allowed in streams around the state) from 210 micrograms per liter to 530 micrograms per liter.
The amount of molybdenum allowed in Blue River segment 14 鈥� also known as lower Tenmile Creek above the Dillon Reservoir, near Climax mine 鈥� was revised to match this new standard.
During a hearing in June, the asked for the old limit, set in 2010, to be increased based on new data. On Aug. 21, the commission decided on 530 micrograms per liter, with an effective date of Dec. 31.
The number was decided upon via a formula that takes into account the reference dose (maximum acceptable oral dose of a toxic substance, below which there should not be adverse non cancer health effects from a lifetime of exposure, set by the Environmental Protection Agency), an average adult’s bodyweight, the percentage of the reference dose allocated to exposure via water intake, average daily water intake and a sub-chronic to chronic uncertainty factor.
Support Local Journalism
The commission increased the acceptable reference dose from 0.03 to 0.06 milligrams per kilogram per day using data from the Agency for Toxic Substances and Disease Registry’s The commission also updated the relative source contribution from 20% to 80% of a person’s daily molybdenum intake, and daily water intake was updated from two to 2.4 liters per day.
The U.S. Environmental Protection Agency reviewed the commission’s new molybdenum standard to ensure it stayed in alignment with the Clean Water Act, which requires states to submit revised water quality standards for review. The Environmental Protection Agency approved the molybdenum water quality standards changes in an official letter on Nov. 25.
What is molybdenum and why are its levels in water regulated?
Molybdenum is a chemical element and mineral that has uses both in the human body and in manufacturing. Molybdenum is used to make cast iron, stainless steel, biofuels, solar panels, catalysts, lubricants and pigments.
Molybdenum is found naturally in several food sources, including legumes, whole grains, nuts, beef liver, leafy vegetables and milk. In the United States, it is recommended that adults consume 45 micrograms of molybdenum in their daily diet. However, too much molybdenum can be harmful.
Climax mine, run by Climax Molybdenum Company, is a major molybdenum mine located in in Lake and Summit Counties, 13 miles northeast of Leadville. The mine began shipments in 1915, and continues to mine molybdenum today, with brief hiatuses over the years.
The mine has the capacity to produce approximately 30 million pounds of molybdenum per year, according to the Climax Molybdenum Company’s parent company
The process of mining for molybdenum naturally releases some molybdenum that would flow into nearby water sources if not for regulation processes that Climax Molybdenum Company is required to conduct to protect people, plants, animals and the environment from potential overexposure.
Too much molybdenum in one’s body can cause kidney and liver damage, reproductive and developmental effects and anemia if ingested orally, according to studies reviewed by the Molybdenum can also cause lung problems and nasal cavity damage if inhaled.
But for healthy people not regularly exposed to molybdenum in the air and soil (like miners), molybdenum toxicity is rare because the kidneys typically handle the process of excreting excess amounts. A bigger concern about molybdenum in water is that it can be toxic to certain animals, particularly cattle and sheep.
The recognized tolerable upper intake level unlikely to cause harmful effects for most adults is 2,000 micrograms per day, according to the . To achieve this amount, a person would need to drink nearly four liters of water filled with the new maximum allowable amount of molybdenum.
Background on regulation of Climax mine’s molybdenum
In August 2010, the commission revised the molybdenum table value standard to 210 micrograms per milliliter based on the 0.03 milligrams per kilogram-day “dietary reference intake” value that was derived by the Institute of Medicine (now known as the National Academy of Medicine), a nonprofit, non-governmental organization. The Institute of Medicine’s recommendation was based on a that focused on the impact of dietary molybdenum on fertility and reproduction in female rats.
At the time, the commission was reviewing a proposal to adopt a table value standard of 35 micrograms per liter to align with the 0.005 milligrams per kilogram-day reference dose in the
The reason given for the higher standard was that livestock do not drink directly from lower Tenmile Creek above Dillon Reservoir.
What does this mean for Eagle County and its neighbors?
Most Eagle County residents and visitors do not need to dwell on the increased allowable instream molybdenum standards, as Climax mine’s molybdenum does not have very much of a direct impact on Eagle County’s water sources. Current measurements of the molybdenum levels in Eagle County’s water show very low levels.
The main body of water affected by the mine is Tenmile Creek, which flows from Copper 撸先生 Resort to the Dillon Reservoir in Summit County. “The impact is primarily in Tenmile Creek. It’s not on our side of it. But we do get some infiltration,” said Dick Cleveland, Eagle River Water & Sanitation District board chair during its Dec. 5 meeting.
