Utah has emerged as one of the nation's biggest releasers of toxic materials, jumping from 17th in 2005 all the way to fourth in the latest inventory from the Environmental Protection Agency, which includes data from 2015.

Utah trails only Alaska, Nevada and Texas.

This rise in the rankings isn't because Utah companies are unleashing more material loaded with lead or chlorine — the overall amount of toxic material released remained relatively steady. But the United States as a whole has seen a decrease over the past decade, causing Utah to climb in the national rankings as other states cut their totals.

Donna Spangler, a spokeswoman for the state Department of Environmental Quality, called the Toxic Release Inventory rankings "misleading" because the reports tend to overemphasize the releases produced by mining operations — and, in Utah, that means the Kennecott copper mine.

The EPA's inventory is built to track certain hazardous substances that could be discharged by large industrial sources. The figures are self-reported and take into account discharges into the air or water, as well as hazards stored in landfills or tailings piles and waste shipped off-site for storage or treatment.

According to the Toxic Release Inventory, 178 Utah facilities reported releasing 229.2 million pounds of potentially hazardous substances in 2015. Heavy metals — lead, copper and zinc compounds — were the top three substances released in Utah, followed by hydrochloric acid and chlorine.

While 1.8 million pounds of these toxins were shipped off-site for disposal in 2015, the vast majority were disposed of on-site. According to the EPA, 8.3 million pounds of Utah's releases went into the air, 110,000 pounds were discharged into a waterway, and 218.8 million pounds were stored or disposed of in an on-site landfill or some similar arrangement.

The overwhelming majority of Utah's releases come from Kennecott. The mine reportedly generated 208.1 million pounds of releases in 2015, or 91 percent of the state's total. The Utah copper mine is the second-largest source of toxic releases in the country, according to the EPA.

A metals mine in Alaska, which reported more than 500 million pounds of releases in 2015, ranks as the largest source.

Kyle Bennett, a spokesman for Rio Tinto Kennecott, said the company's toxic release can be explained by the nature ofthe operation.

A lot of the material surrounding the ore Kennecott mines contains naturally occurring trace metals such as lead and zinc, which have been detected in airborne dust in the Salt Lake City area. If Kennecott moves this unwanted material, called overburden, while digging for ore, then it reports the trace metals as a release.

"We're a large mine, and the amount of material — we can move approximately half a million tons of overburden per day," Bennett said. "For every one ton of ore, we release less than one ounce of lead … it is the sheer amount we're moving that makes that add up."

Consequently, he said, Kennecott's releases — and therefore Utah's overall totals — have remained relatively consistent during the past decade. The exception, Bennett said, came in 2013, when Kennecott's mine ran into a layer of rock that contained unusually high concentrations of lead and other metals.

That year Utah's total was 525.5 million pounds. The state has averaged just over 200 million pounds per year since 2005.

Bennett said he does not believe Kennecott's releases pose a threat to the health of Utahns, but he said the company is committed to reporting its releases to the public.

"It is important for people to have access to data and information," he said. "We are committed to maximum transparency."

Utah's second-largest source of toxic releases, US Magnesium, has followed the national trend more closely. The Tooele County company has cut its emissions significantly, though the majority of those reductions took place more than a decade ago.

Tom Tripp, the company's technical services manager, said the reductions were a result of new pollution controls installed in 1990 and 2001.

In 1987, US Magnesium captured 85 percent of the chlorine it produced, and released 15 percent. Today, the company captures more than 99 percent of its chlorine, Tripp said, "so we've made pretty good improvement."

Chlorine emissions make up the large majority of the releases US Magnesium reports to the EPA. In 2000, before the 2001 installation of additional emission controls, US Magnesium reported releasing nearly 44 million pounds of toxic materials. In 2002, the company was down to less than 15 million pounds. The company reported just under 6 million pounds of releases in 2015.

Tripp attributed the reductions primarily to technological advances.

The Bonanza Power Plant, located near Vernal and owned and operated by the Deseret Power Electric Cooperative, and EnergySolutions, a hazardous waste handler located in Tooele County, round out the state's top four sources of toxic releases, according to the EPA. Those sources contributed 2.3 million pounds, and 2.2 million pounds, to the state's total releases in 2015, respectively. Multiple attempts to reach either company for comment were unsuccessful.

Francisco Kjolseth | The Salt Lake Tribune Nearly 6- months ahead of schedule, top-to-bottom access within the Bingham Canyon Mine returns with the opening of KennecottÕs new 150 ft wide mine access ramp. On Wednesday, Nov. 6, 2013, mine operators granted access to see the progress that has been made with 14 million tons of material removed so far following the 150 million ton slide that shut down operations for 17 days.
Al Hartmann | The Salt Lake Tribune Trucks continue roll with ore beneath the western wall of Bingham Canyon Mine that has had small movements and caused a small slide in the center of the photo. Kennicott uses sophisticated monitoring and detection systems in additional to hundreds of trained eyes in its everyday operation to scan and detect movement and keep people safe. State of the art GroundProbe slope stability radars, prisms and other systems are used to detect movement in the walls of the Bingham Canyon Mine.