Snake River in Idaho - Fall 2025
As background, Zebra and Quagga mussels were introduced into North America in the bilge water of ships from Europe. With time, these mussels spread through the Great Lakes in Canada and the U.S., into Manitoba, and in many areas of the US. One of the primary ways the mussels spread west was in the bilges of private boats that became infested in eastern Canada that were subsequently moved to Manitoba lakes. To date, the mussels have not spread further west in Canada. However, the economic and recreational consequences should they become established in BC are enormous, especially as the control or elimination of the infestation is very difficult and expensive.
For several years, SWOA has been tracking the defensive measures being undertaken by the Canadian Federal and Provincial governments to prevent the introduction of Quagga or Zebra mussels into BC and, particularly in the Shuswap Watershed. To date, these defensive efforts have been successful. However, SWOA continues to encourage all our members to be vigilant in identifying any activities that could result in the introduction of these species into our watershed.
As SWOA reported in a earlier newsletter, quagga mussel.vigers (larvae) were found in the Snake River in Idaho in 2023. This is a major concern as the Snake River is a tributary to the Columbia River the headwaters of which are in eastern B.C. In 2024, the Idaho Department of Agriculture “attacked” the infestation with a chelated copper compound in the 7.2 miles of the river where they were found. A report by the Department on the 2024 work indicated that the treatment was partially successful (reducing the infested area by 50%). Monitoring following the 2024 treatment detected some further quagga mussel vigers in selected deep-water habitats, requiring further treatment in 2025. The results of the 2025 treatments are not yet available.
While the treatment appeared successful in the relatively confined riverine environment, the likelihood of a successful application in a lake environment is unlikely in our view. However, it was especially concerning to learn that during the treatment, all uses of the Snake River, including extraction of water for use by both humans, domestic animals and for recreation were prohibited during and following the treatment for several months. If Zebra and Quagga mussels were to be detected in Shuswap or Mara Lakes, can you imagine the effect of having to use the type of treatment used in the Snake River, over a period of even a part of several years, would have on the use of our lake! The loss of the use of the lake likely would be devastating to all lake users including municipal (such a water supplies), recreation, tourism and industries.
SWOA will continue to monitor the situation in the Snake River as monitoring results become available.
For more information do an internet search for Snake River mussels.