Butte-Silver Bow and Montana Resources are proposing to pump additional water from Silver Lake to increase flows in Blacktail and Silver Bow creeks.
Under the terms of a draft Water Service Agreement between Montana Resources and Butte-Silver Bow, which administers the Silver Lake Water System on behalf of the county's citizens, water for in-stream flows for Butte's creeks would be increased from a maximum flow of 3 million gallons a day to some 7 million gallons a day. The increase would bring a maximum average annual volume of 2.15 million gallons per day.
The increased flows will benefit the Butte watershed, the community and Superfund activity in the Clark Fork Basin, say Mark Thompson, Montana Resources' environmental officer, and Jon Sesso, Butte-Silver Bow's Superfund coordinator.
None of the additional Silver Lake water would be used industrially. But augmenting stream flows could help assure that water being discharged from the Berkeley Pit, via the Horseshoe Bend treatment plant and the new polishing plant built by Atlantic Richfield, meets aquatic-insect survival tests.
"The water from the polishing plant has to meet metals standards right from the pipe (with no dilution from water in creek)," Thompson said, "and it does." But the additional water could help with the-so-called "wet test," which measures the survival of aquatic life in the form of Daphnia magna, a water flea.
Currently, Sesso said, the Butte area has instream-flow rights to 3 million gallons a day, dating from the restoration work on Silver Bow Creek in the mid-2000s. But the additional water could be key to the county's hopes for restoring the cutthroat trout fishery in Blacktail Creek.
"Blacktail is our most critical resource," Sesso said. "We consider a minimum flow of 10 million gallons a day as what we need for the health of critters and the health of the stream. Some days, it will hit 10 million gallons a day and more on its own. Other days, it gets really low, and that's when this water would come into play."
Temperature is as important a factor to stream health as the size of the flow, and cold, pure Silver Lake water will be beneficial both ways.
In 2017 and again in 2019, in a pilot program, the state Natural Resources Damage Program purchased Silver Lake water to increase flows and lower temperatures in Warm Springs Creek and the Upper Clark Fork River — critical habitat for the endangered bull trout.
While it is certainly possible that those tests spurred some in Butte to think that the Silver Lake water should be deployed closer to home, Sesso says he believes there is enough water for both uses.
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"Absolutely there is," he said.
Joe Griffin, a hydrogeologist who once supervised the Butte Hill cleanup plans for the state Department of Environmental Quality, is now on the technical advisory committee of the Clark Fork Coalition. He's not so sanguine about the amount of water available, and believes the Warm Springs Creek and Clark Fork bull-trout protection should take priority. "Long term, I think it's the most important" use of the water, he said.
Under the terms of the proposed deal, Montana Resources would pay a one-time $300,000 fee which goes into a trust fund designed to cover any major repairs the Silver Lake system might need. Also, it would pay $178,000 per year in quarterly payments to Butte-Silver Bow for the value of the in-stream flows. As written the agreement is for four years with a two-year renewal option.
MR has also agreed to cover costs associated with the necessary filings with the state Department of Natural Resources and Conservation; will pay operating and maintenance costs — and will pay for the pumping of all Silver Lake water that is brought to the Butte Hill.
The increased flows would also be helpful to the Butte Metro Sewer in helping with water-quality compliance.
Sister Mary Jo McDonald led a class-action group that sued Dennis Washington over Silver Lake water in 1990. In 1996, the group prevailed, and the people of Butte took ownership of the system.
On Tuesday, McDonald expressed cautious support for the potential agreement.
"This proposal, at this point, seems like a good thing for Butte, if this water comes into the system at Texas Avenue. It's the water that can enhance the environment for native fish to prosper and survive, and all the small creatures in the stream that need good clean water.
Eventually this water can even help conditions downstream, she said, but only after "it helps Butte first for a change."
The proposal will be presented to the Council of Commissioners Wednesday, and a week after that, the council will be asked to authorize Chief Executive Dave Palmer to sign the agreement.