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Federal agency examining sediment from Aztec reservoir
Water conference focuses on mine spill and its effects
FARMINGTON — The U.S. Geological Survey is analyzing sediment removed from an Aztec city reservoir to help analyze the lingering impacts of the Gold King Mine spill.
The reservoir was built in 1947 and has not had its sediment removed since then.
Hydrologist and geochemist Johanna Blake described the U.S.G.S. work at the reservoir during a presentation at the third annual Conference on Environmental Conditions of the Animas and San Juan Watersheds today at the Henderson Fine Arts Center at San Juan College.
The conference focuses on water quality and began after the Gold King Mine spill of August 2015.
“The Gold King Mine spill kind of opened up a lot of eyes as to what could be happening in these watersheds,” Blake said during the conference.
The Gold King Mine spill was not the first mine spill into the Animas River. In addition to mine contamination, Blake said historical uranium mining and processing in Durango, Colorado, as well as wildfires could impact water and sediments in the Animas River watershed.
The Animas River is the sole source of drinking water for the city of Aztec. Aztec has multiple reservoirs, but they are all fed by the river.
The city drained the reservoir in the fall for dredging, and Blake said she took her last measurement about a week ago.
“We’re still in the infancy of this,” she said.
The U.S.G.S. hopes the study of sediments will help scientists understand metal contamination over time in the Animas and San Juan rivers, potential impacts to the drinking water treatment process, and what options are available to protect water quality, according to the presentation abstract.
Blake said the study involved digging four trenches and taking samples from those trenches. She said there was between 120 and 150 centimeters of sediment at different points in the reservoir.
Blake was one of more than a dozen people who delivered a presentation during the conference today.
EPA scientist says mine spill sediments no longer in river watersheds
Kathleen Sullivan, a senior researcher in the National Exposure Research Laboratory of the U.S. Environmental Protection Agency’s Office of Research and Development, said the water quality in the rivers has improved since the Gold King Mine spill. She said samples taken in 2017 showed historic low levels of metal concentrations. That was based on 15 years of data.
Sullivan said the majority of heavy metals from the Gold King Mine spill that were deposited in the Farmington area were washed out during the 2015 monsoon storms.
Weeks after the Gold King Mine spill, northwest New Mexico saw heavy rains that caused flooding and prompted declarations of a state of emergency.
However, Sullivan said the majority of the heavy metals from the spill were deposited in the Animas River between Silverton and Durango, Colorado. She said that sediment was likely washed out of the watershed during the spring runoff in 2016.
The conference continues Thursday.
Hannah Grover covers government for The Daily Times. She can be reached at 505-564-4652 or via email at firstname.lastname@example.org.