ELKO – Mining is more than just moving dirt, it also can be about moving water.
Progressive Leadership Alliance of Nevada and Great Basin Resource Watch hope to continue a conversation on how pit lakes will affect the water tables throughout the state. Last year PLAN released a hydrology study on the impacts of mining on the Humboldt River drainage basin and the group commissioned a follow-up report.
Tom Myers, who has a doctorate in hydrology and hydrogeology, produced both reports. He presented them in July at Great Basin College.
Last year’s study identified the deficits to the river basin’s water caused by mining: the pumping or dewatering in the pits and underground mines, the pit lakes, and the loss of water through evaporation.
“The question is how do you make up those deficits,” Myers told the Free Press during an interview July 6 before his presentation.
He said there has never been enough data to measure where the water is going once a pit lake forms in or near a river basin.
“There’s now enough data since Lone Tree stopped dewatering at the end of 2006,” he said.
He has data from gauges covering a 32-mile reach along the river, and the data stretches back into the 1940s.
“I was able to take a look at that and to show a very significant change in the flow relations along the river,” he said. “From the mid ‘90s to the mid 2000s there was almost no water loss between the upstream and the downstream gauge, whereas after 2006 there’s a huge loss and it’s a lot more than what would have happened prior to dewatering.”
Myers said a river in an arid area naturally loses water. He said he had to put together data spanning decades to determine any effect of mine dewatering.
“Basically about 40 percent of the water that enters the reach is lost since 2007, whereas prior to that it was more like 19 percent,” he said. “Since 1940 there has never been that kind of loss, so you can say what are the different conditions on the system?”
Myers said the main different condition is the formation of a pit lake at Newmont Mining Corp.’s Lone Tree site. While the mine was in operation it was dewatering the pit. The company pumped 780,000 acre feet to dewater at Lone Tree, Myers said. While it was operating the mine discharged the water back into the river, so there was no “observable loss.”
However, now that the mining has stopped, the water is collecting in the pit rather than moving toward the river, Myers said.
He said the concern is that Lone Tree is the first of at least six mines that will eventually close in the future.
John Hadder, director of Great Basin Resource Watch, said he is concerned about the water in the pit lake not being used.
Ellen Moore, PLAN mining justice organizer, said her group commissioned the two reports to begin a conversation with lawmakers, regulating agencies and the mining industry.
“The end result (of the studies) is to contribute to a discussion about something that we think, based on the data and the research, is currently a problem and is going to continue to be a problem in the future and that we feel like is currently not being adequately addressed,” she said.
Both PLAN and Great Basin Resource Watch would like to see the mines reclaim their pits. They said if the mines had to reclaim their pits, they could design them with reclamation — and possibly recreation — in mind.
After the first report was published last year, Mary Korpi, who was the Newmont director of external relations in 2015, said the company has done several studies on the effect of the pit lake. She said Lone Tree’s pit continues to fill with water and it will take about 60 to 70 years for it to reach equilibrium.
While the pit is filling with water, the highwalls can be “inherently unstable,” so the pit would not be suitable for recreation, Korpi said in 2015. However, once the lake reaches equilibrium, it could be used as a “water source reservoir if approved through the regulatory framework of the State Engineer,” she said.
Hadder said wanting reclamation doesn’t mean he wants to see them filled in with dirt. He said he thinks the pit lakes that form should be usable by the public, whether as a recreation area or possibly a fishery or other uses.
“What’s really important here is the water,” he said.