Dewatering

Great Basin Mine Watch

Dewatering Issues


Containing 570,000 acre-feet of groundwater when full, Barrick's Goldstrike Pit will be the largest pit lake in the region and larger than any other human made lake in Nevada.	Dewatering in the Humboldt River watershed (see map below), will create a deficit of 5,000,000 acre-feet, which would require more than 30 years of the entire flow of the river to fill.

The pit lake at the Yerington Mine has more than 40,000 acre-feet of water in it. It sits within 1/3 mile from the Walker River and may be drawing water from that river.	Infiltration basins, such as these at South Pipeline, are a necessary means of returning the water removed from aquifers for mining to the aquifers.

At least 16 mines in the Humboldt River basin extended below the water table. Five mines alone will create a 5,000,000 acre-foot deficit in the basin when they close by 2015. Mitigating the damages from dewatering is Great Basin Mine Watch's highest priority.

Dewatering is the process of removing groundwater from around a mine that extends below the water table. Throughout the Humboldt River basin, the mining industry will cause a deficit of 5,000,000 acre-feet of water; it will require at least two centuries to recover. Streams and springs will be affected, some being totally dried for decades.

Pit lakes form when the dewatering wells stop pumping. In the Humboldt River basin, there will be approximately 1,500,000 acre-feet of water in pit lakes. See the following map. The future water quality of these lakes is uncertain, but will likely be poor. Nevada does not regulate the quality in the lakes so long as they do not degrade surrounding groundwater. In other words, the state allows a huge water resource to go unprotected.

The Humboldt River basin contains more than a dozen mines which will fill with water when dewatering ceases.

Last updated on April 16, 2003