Eastern Idaho Water Rights Coalition Members:

Last week a very informative annual meeting of the Idaho Water Users Association (IWUA) was held in Boise. One particularly interesting session was a presentation on the on-going efforts to control Quagga Mussels in the Snake River near Twin Falls as well as a new invasive threat to our waterways called Golden Mussel.

Golden Mussels were found in the Stockton, California docks in October of 2024. In the short time since they have spread through much of the Central California waterway system. Photos were shown of where they have colonized a fish sorting facility. Workers have to use square shovels to scrape the mussels off of the raceways and deposit them in dumpsters for disposal.

The newly discovered mussel is far more aggressive than the Quagga and Zebra mussels that had been the target of our previous concern. A primary reason is that the Golden Musset only requires one part per million calcium in water in order to grow, whereas the Quagga and Zebra mussels require from 7 to 10 parts per million to grow. This makes the new mussel a much greater threat to our headwater streams and lakes that have lower calcium content. In addition if these new mussels don't like where they are growing they have the ability to disconnect themselves from the surface and move to a more favorable location.

The good thing is that all of the measures employed to identify and prevent Quagga and Zebra mussel infestations will also work for the Golden mussel. It does highlight the importance of continued vigilance in the states' detection surveys and boat cleaning inspection stations, as well as the publics' increased responsibility to drain, clean, and dry their boats when moving them from one water body to another.

We saw a very impressive presentation on the state's Quagga mussel eradication program on the middle Snake River. Idaho Department of Ag personnel had identified areas in various parts of the river and adjacent pools where rocks and deep pools had caused stratification of the water where the pest controlling chemicals had likely not reached the required level of concentration in previous years. Special underwater booms were employed to apply the chemicals directly where needed. ISDA staff spent 6 to 8 weeks living on-site in camp trailers last fall while the effort was underway. The good news is that only about half the distance of previously treated river need to be treated in this third year of the eradication effort.