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Water level in Butte's Berkeley Pit has not risen after year of pumping

Posted at 7:25 PM, Sep 17, 2020
and last updated 2020-09-18 15:01:11-04

For the past year, the toxic water from Butte’s Berkeley Pit has been treated, cleaned, and pumped out into Blacktail Creek. As a result, the water in the pit has not risen even an inch.

“We can reassure this community that management of the pit is completely possible,” said Mark Thompson, vice president of environmental affairs at Montana Resources.

The water has not risen above 5,356 feet since last September, keeping it below the protective water level of 5,410 feet.


“It’s been going great, it’s been a great project, things are functioning as anticipated,” said Thompson.

Montana Resources has been pumping water from the pit to the settling pond and treating. The water is then taken to the polishing plant owned by Atlantic Richfield for a final cleaning before it pumped into the confluence of Silver Bow and Blacktail Creek.

“The water gets tortured pretty, the pH is adjusted up to neutralize the acid, remove the metals and at the polish plant it’s adjusted back down to normal pH of creek water,” said Thompson.

With more than a billion gallons of water already pumping into this creek at this point, the Berkeley Pit has managed to stay just over 50 feet below the protective water level. Now they do plan to try to lower the water level in the pit, but they’re going to take their time and it’s going to happen slowly.

“Dropping the water too fast, if you do it slowly, it can be a lot safer, but if you drop it too fast that’s when you can run into some problems,” said Thompson.

The water in the pit rises an average of about 6 feet per year.