This is an archived article that was published on sltrib.com in 2016, and information in the article may be outdated. It is provided only for personal research purposes and may not be reprinted.
State regulators are calling for more study of Lake Powell and sections of the San Juan River in light of unusual test results that may or may not be tied to last summer's Gold King Mine spill.
Two sections of the San Juan River were added to the state's list of "impaired" waters in the latest state water quality report. Those portions of the river were found to have concentrations of aluminum, cadmium, copper, iron, lead and mercury that exceeded state water quality standards on at least two occasions last fall.
The state also added portions of Lake Powell to the list a move that greatly increased the overall percentage of freshwater lake acreage deemed as impaired, said Walt Baker, director of the Utah Division of Water Quality (DWQ). In the state report, released this week, 71 percent of Utah's freshwater lakes did not meet the water quality standards for their designated uses, which include providing drinking water, recreation or wildlife habitat.
The overages in the San Juan River were detected by the Environmental Protection Agency while the feds were sampling the river to evaluate the fallout from the Gold King Mine blowout upriver, and are possibly related to the Aug. 5 incident, said Erica Gaddis, assistant director of the DWQ.
Gaddis said the department had feared this spring's runoff could dislodge even more contamination and flush it downstream, but so far, the division hasn't found evidence of that. And though portions of Lake Powell are listed as impaired, it's unlikely that it's related to the Gold King Mine, Gaddis said.
Water directly downstream of the mine saw decreased pH levels becoming more acidic immediately following the Gold King spill in August, but Lake Powell has had unusually high pH readings a situation that itself is a mystery.
Now, the division's scientists are also wondering where the estimated 880,000 pounds of heavy metals released during the August 2016 Gold King Mine incident ended up.
The common thought, Gaddis said, is that the metals were deposited in sediment somewhere upstream, on the Animas River in Colorado and that they remained there, waiting for high river flows to flush them out.
It's possible that those metals are already making their way downstream, she said, and increased river flow could be diluting the metals so that concentrations remain below the state's screening values.
The potential for further contamination pushed the state to develop a long-term monitoring plan for the San Juan and Lake Powell, the likely final resting place for all that sediment, should it make its way farther down the river.
As part of that plan, the state has installed devices on the river capable of measuring the amount of sediment in the water in real-time. That data is available to the public at water data.usgs.gov.
It's not yet clear how the amount of mobilized sediment correlates to the concentration of metals in the river. Gaddis said it could take another year for the DWQ to create a working model that will be used to issuing warnings when the river may be contaminated.
Gaddis said she does not believe any drinking water systems are at risk for contamination, though the state is monitoring some nearby systems just in case. The recreational use of the river is more concerning, she said, though the data so far suggest the river is safe for boating.
The primary concern, Gaddis said, is aquatic life. The state is also watching aquatic life in the region to determine whether metals in the river, or in the river's sediment, are potentially harming fish or other creatures that live in the river. Gaddis said the DWQ has yet to see direct evidence of metals poisoning.
The long-term monitoring plan is anticipated to cost $1.2 million altogether, Gaddis said. So far the EPA has offered Utah $645,000 related to the Gold King Mine spill. Gaddis said the state intends to apply all of that money to its monitoring initiatives.
The state also intends to sue the EPA for its role in the Gold King Mine incident. Wade Fairway, an assistant Utah attorney general, told lawmakers during a Tuesday interim legislative meeting that his office was still in the process of hiring outside legal counsel to assist with the suit.
Meanwhile, Gaddis said, the DWQ has begun to turn its attention to the chronic effect of mining in the Bonita Peak Mining District in Colorado and on the San Juan River and its tributaries. The Gold King Mine alone, she said, could have released between 500 million and 850 million gallons of contaminated water over the past decade, and it's just one of 48 old mines in the Bonita district.
The EPA proposed making the entire Bonita district a superfund site this past April.
Gaddis said there is reason to believe that the metals and other contaminants leaked from those old mines over the course of history ended up in Lake Powell. The U.S. Geological Survey collected sediment cores from Lake Powell in 2010, she said, and demonstrated a clear pattern of increasing metals in the sediment. The DWQ is talking with the USGS about taking additional cores, perhaps later this year, to determine whether that trend has continued.
The DWR is also currently studying sediment contamination, Gaddis said, in order to develop standards for the acceptable amount of heavy metals in sediment. The state currently has no such standards, Gaddis said, which could be used to evaluate whether future sediment samples indicate the presence of an environmental hazard.
The division will also be digging into Lake Powell's pH problem.
Over the course of four years, 10 water samples from Lake Powell registered a pH above 9 an alkalinity similar to baking soda or sea water, according to the USGS. These samples were collected from seven separate locations, on five unique dates, Gaddis said. The highest reading, she said, was 9.6, and the lake has registered a below-standard pH only once in that time period.
"We don't know what's causing that," Gaddis said. "We'll be looking into the causes."