Montana could drain Billings’ Lake Elmo to address invasive clams

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Lake Elmo

A small amount of open water remains around Roger’s Pier on the south side of Lake Elmo on Wednesday.

Lake Elmo is the first body of water in Montana to see invasive Asian clams, and state wildlife officials are eager to ensure it’s the only place in the state where they’re found. 

“It creates a sense of urgency,” said Bob Gibson, a spokesman for Montana Fish Wildlife and Parks. 

One option being considered by FWP is draining Lake Elmo. Cold and dry conditions are one of the best ways to eradicate the species, said Gibson. 

But before the state takes any action, FWP officials will study several options and include public input.

“We’re a long way from draining the lake,” Gibson said. 

The tiny clams were discovered last year during a Fish Wildlife and Parks training exercise at Lake Elmo designed to teach state wildlife workers how to discover and identify invasive species. The training worked exactly as designed, apparently, because it turned up the Asian clams, mostly clustered near the boat ramps. 

Asian clam

Several small, quarter-sized Asian clam shells were found on the shore of Lake Elmo in 2019. The clams are considered an invasive species.

Others were found a little further out in the sediment, leading FWP biologists to hypothesize the clams may have been in the lake for several years. 

“It looks like they’ve been there for a while,” Gibson said. 

Invasive Asian clams found in Lake Elmo during training session on detecting invasive species

FWP biologists aren’t sure how the clams ended up in Lake Elmo, but they have a few ideas. The fact that they’re concentrated around the boat ramp means they could have been brought in by watercraft; the Columbia River Basin is home to large populations of Asian clams, Gibson said.

The clams are also popular at pet stores for fish aquariums. The mollusks are small — about the size of a dime, with round, ridged shells. It’s possible someone emptied their fish tank into the lake, Gibson said. 

This spring, FWP will conduct an environmental assessment to scope the problem so the state can then design possible solutions. Since placing the clams in cold and dry conditions is one of the best ways to eradicate them, draining Lake Elmo is a possible solution. 

But it’s a complicated one. In order to drain the lake, FWP would have to figure out what to do with the fish, turtles and other wildlife in the lake, and how to deal with the waterfowl that live around it, Gibson said. 

Lake Elmo

A fish swims under Roger’s Pier on the south side of Lake Elmo on Wednesday.

There’s also the issue of how to move the water. 

Draining the lake involves more than just pulling a plug, said Gary Davis, president of the Billings Bench Water Association board. Lake Elmo is a state park, but the water is supplied through Billings Bench Water Association’s irrigation system. 

The state could drain off the lake’s first few feet through lateral canals, but to get it completely empty the rest of the water would have to be drawn out, Davis said. 

“It would require pumping,” he said. 

So the environmental assessment could find that leaving the clams may be the best solution, Gibson said. 

The state would also seek public comment on any plan. While draining the lake would be complicated, it would allow the state to do work on fish habitats and improve recreational infrastructure. Getting public feedback would be vital to anything the state does, he said.  

“That’s who we want to hear from,” Gibson said. 

After a warning was issued last week for the presence of blue-green algae in Lake Elmo, state officials are checking water samples and looking…

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