Source: Montana Public Radio October 1, 2019

This week, for the first time ever, once toxic water from the Berkeley Pit, the abandoned open pit copper mine in Butte, is being treated and released into the headwaters of the Clark Fork River.

It’s Monday afternoon and I’m standing on the banks of Silver Bow Creek in the center of Butte with Ron Halsey, an operations manager for Atlantic Richfield. We’re watching an endless rush of clear water cascade through a man-made rock wall into the stream, which is one of the headwaters of the Clark Fork River. “Seeing the water come out of the rocks there, and having discharge to the creek has been …the best part of the day so far,” Halsey says.

He’s in high spirits because while there’s no official ribbon cutting, or pomp and circumstance, we’re witnessing an historic milestone in Butte’s Superfund clean up.

Thirty seven years ago, Atlantic Richfield, a former oil company now owned by BP, abandoned the Berkeley Pit and allowed the former open-pit copper mine to start flooding with acidic, heavy metal laden mine water.

Now, with a green light from the Environmental Protection Agency, treated water from the Berkeley Pit is being released into Silver Bow Creek for the first time. “Today we’re discharging about six million gallons per day, or about 5,000 gpm, gallons per minute,” Halsey says. That sounds like a lot, but the Berkeley Pit currently holds about 50 billion gallons of toxic water. Left to its own devices it would keep flooding, and eventually breach the bedrock and contaminate Butte’s aquifer and creeks.

But under Superfund requirements, the two companies in charge of the Pit are legally required to prevent that from happening. Last year, Atlantic Richfield and Montana Resources, which owns the active copper mine next door, launched a pilot project to start managing the Pit well before it reaches that so-called “critical level”. Ron Halsey says, “The combination of Montana Resources pumping water from the Pit, and then us treating it and discharging it, is the proof that we can actually hold the water level steady in the Pit.”…

According to Atlantic Richfield, the water being released into the creek is continuously monitored and sampled every day. If there’s ever an issue with quality or flow, they can adjust or stop it as needed. Tim Hilmo, a project manager with Atlantic Richfield, says the company believes that putting clean water into the stream will have beneficial effects on the watershed…

So far, the discharge of treated Berkeley Pit water into Silver Bow Creek has been regarded in Butte as a positive and long awaited step forward.

If everything stays on track, Atlantic Richfield plans to ramp up to 10 million gallons per day over the next few weeks. The company is still in discussions with EPA and Montana Resources about building an additional water treatment plant to draw the level of toxic water in the Berkeley Pit down further.