Plans to drain Lake Elmo in Billings Heights to eradicate invasive Asian clams will move ahead after Montana Fish, Wildlife & Parks finished an environmental review of the proposal this week. This drawdown to address invasive claims will also help other efforts. The project includes plans for new fish habitat, angler access and state park improvements while the lake is dry.
The plan calls for FWP to drain the lake starting in September 2021. The invasive clams would dry up, starve and freeze dead during the winter. Billings Bench Water Association, which manages water in the 60-acre irrigation reservoir, will refill the lake from its adjacent canal in April of 2022. FWP will restock fish when the later level is sufficient.
While the lake bed is dry and planning and design are completed, FWP will build a number of improvements that would be difficult or too expensive with water in the lake. They could include rock jetties, boardwalks, bank and dog park improvements and new fish habitat.
Invasive Asian clams were discovered in Lake Elmo in 2019. While they are present in the Columbia River basin of Washington and Oregon, this is the first time they have been seen in Montana. It is unclear how they arrived in Lake Elmo, but possibilities include a contaminated boat or someone emptying an aquarium into the lake.
The invasive clams can reproduce quickly and in large enough numbers to clog irrigation and municipal water systems. They filter out water nutrients that are necessary to support desirable fish and organisms in the food chain. FWP also is concerned that, unchecked, the clams could spread through irrigation ditches to the Yellowstone River and beyond.
The decision to proceed with the project was made after months of environmental review and public comment on various options.
A copy of the decision to proceed with the projects is online at: http://fwp.mt.gov/https://fwp.mt.gov/public-notices/news/2020-12/2020-12-29-lake-elmo-decision-notice