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Monday, May 27, 2024 | Back issues
Courthouse News Service Courthouse News Service

Montana Waterways Invaded by Aquatic Mussels

Montana is in the midst of a statewide natural resource emergency after samples detected invasive aquatic mussel larvae, or suspicion of their larvae, in at least two major reservoirs.

HELENA, Mont. (CN) – Montana is in the midst of a statewide natural resource emergency after samples detected invasive aquatic mussel larvae, or suspicion of their larvae, in at least two major reservoirs.

The suspicious samples were found in and upstream of the Canyon Ferry Reservoir, toward the headwaters of the Missouri River east of Helena. The positive samples were taken from Tiber Reservoir in north-central Montana, along the Marias River. Scientists aren’t sure whether the larvae are from thumbnail-sized zebra mussels or their larger cousin, the quagga mussel. They cling to everything from tennis shoes to docks to intake pipes, generally taking over a water body’s ecological health. They also can wreak havoc for irrigators and dam operators.

The federal Government Accountability Office estimates $260 million per year is spent trying to fend off invasive aquatic species, including mussels, Asian carp and sea lampreys, with limited success. The National Wildlife Federation notes that the quagga and zebra mussels originally came to the United States from Eastern Europe in the 1980s in the ballast water of ocean-going ships. By 1990, they had infested all of the Great Lakes, and the federation created a time-lapse map that show the mussels’ spread to 36 states, including Texas, Nevada and California.

“The invasion underscores the immense challenges and difficulties of dealing with invasive species once they take hold,” said Jordan Lubetkin, a senior communications manager with the federation’s regional office in Michigan. The federation successfully sued the U.S. Environmental Protection Agency in 2013 to strengthen rules to limit the spread of invasive species through ballast water, and Lubetkin anticipates new regulations to be implemented soon.

But that won’t undo the damage already done to Lake Erie, where Lubetkin grew up. The water used to be muddy, but now is so clear you can see through it.

“While it’s clear though, it’s not clean,” he said. Mussels effectively filter water that typically feeds other aquatic dwellers, removing their food sources. They also excrete phosphorus, which coupled with runoff from agriculture operations, is causing massive algae blooms.

Noting the potential disaster, Montana Gov. Steve Bullock signed an executive order in recent weeks creating an interagency rapid-response team to try to identify and contain existing mussel populations, and prevent future introduction to other waterways. He pointed out that Montana is a headwater state for three regionally significant river systems and that the economic, environmental and recreational impacts of a mussel infestation could have national implications. It also could significantly impact hydroelectric dams and municipal water supplies.

“The potential economic, ecological and recreational impacts for Montana and our region must be addressed quickly and every effort must be taken to prevent the additional spread of this threat,” he said in a press release.

The response team reported Wednesday that about 75 percent of the 140 samples taken from water bodies across Montana all came back negative for larvae. Scientists are working “close to around the clock” to process the remaining 25 percent of the samples, according to incident commander Randy Arnold. Once Tiber and Canyon Ferry reservoirs freeze for the winter, they’ll perform additional sampling in a grid-like pattern to continue to gauge the extent of the suspected invasion.

Like other states, Montana has instituted boat checkpoints, where they’re inspected for mussels. Experts say once they’re established in a water body, there’s little anyone can do to stop their spread.

However, Marc Gaden, a scientist with the Great Lakes Fishery Commission – a cross-border U.S./Canadian group – said a new chemical called Zequanox is showing some positive effects.

“In confirmed water bodies it could be effective in preventing them from taking hold or getting rid of them in small numbers,” Gaden said. “They’re an approved molluscicide for zebra and quagga mussels that aren’t supposed to harm humans, animals, aquatic life or the ecosystem. Nothing, obviously, is risk-free but you have to weigh that against the irreversible harm they cause.”

Categories / Environment

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