Growing concerns over the medium and long term impacts of open-pit gold mining on Nevada’s water were validated earlier this month when Dr. Tom Myers presented his third report on the effects of mine dewatering and pit lake formation on Humboldt River flows. PLAN traveled to Elko and Lovelock to share the findings of the most recent study with residents and impacted farmers. Read local news report from the meetings in the Elko Daily Free Press and Lovelock Review-Miner.
Read Dr. Myers’ full report and presentation on what happens to ground water after mining ends and the pit lake fills with water, or check out our summary below.
Open-pit gold mining impacts our water –
even after production, profits and jobs are gone
While the mine is in operation:
- Over the course of a decade, companies carrying out open pit mining drain the aquifer of groundwater that took hundreds or thousands of years to accumulate. This quick suck significantly lowers the water table.
- Mining companies claim they put more than half of the water back into the basin, but this is not the same as leaving water underground, in storage. Dewatering forces us to use the water now, instead of planning for the future.
FACT: Since 1991, 3.9 million acre feet of water was pumped from open pits in the Humboldt River Basin. One acre foot, or 326,000 gallons, is enough water for a family of four for one year. That means mines have pumped enough water to support 3.9 million Nevada families.
Immediately after mining ends:
- Water pumping ends and the giant pits begin to fill up with ground water. This causes a slow suck of the water table over the course of decades. The slow suck results in a decrease in the water table and less water in the river. Increased flows while a mine is in production is due to water being pumped from the pit and discharged to the river.
- Data from Newmont’s Lone Tree pit lake shows significant water loss in the Humboldt river since the company stopped dewatering the mine in 2007.
FACT: Since 2007, the water being wasted to fill up the Lone Tree pit could have supplied nearly 9,000 families for 20 years (176,00 af between 2007 – 2016).
For the foreseeable future:
- A pit lake lasts forever, so that means water lost to evaporation off the pit lake will also be eternal.
- 10,000 acre feet a year are lost to evaporation – the mining industry might say this number is insignificant, but we believe mining companies should not be allowed to waste any water, no matter the amount.
FACT: In 18 years, we will have lost 180,000 acre feet of water to evaporation – the same amount Las Vegas wants to pump from Northern Nevada.
Now consider the medium to long-term impact of dozens of open pit mines scattered across the state. Is open-pit gold mining the most sustainable and responsible use of our precious water?
Recommendations to protect our future:
- Require that pit lakes are reclaimed for post-mining beneficial use.
- Demand enforceable water quality regulations on pit lake water.
- Require the mining industry apply for water rights on evaporative losses from pit lakes.
- Reform “temporary” water permits for mine dewatering to require companies to regularly justify water use as compared to other demands. Currently, these “temporary” permits for mining are valid for decades, but are not even calculated in overall water allocations.