A Changing Map of Risk
With the recent discovery of mussels in Montana, the map of zebra and quagga mussels has just changed.
The density of veligers (mussel ‘spores’) is not high, and the Montana Fish and Wildlife and Invasive Species Alliance are working hard to contain the infestation. No adult mussel infestations have yet been located.
At the same time, Shelby Montana is not only in the centre of what were previously that last states and provinces to be mussel-free, it is also at a transportation crossroads. The map below shows the relative location of the Tiber Reservoir, where the mussel veligers were discovered, and Shelby Montana, Coutts, Alberta, and the intersection between the Interstate 15 and the US 2 in Shelby Montana.
On a watershed basis, the water in the Tiber Reservoir is from the Marias River, which flows east from Glacier National Park towards the Missouri. The Clark Fork of the Columbia River Basin emerges west out of Glacier National Park and the Blackfoot River to the south on its eastern border.