For the past three years, during the month of October, Idaho Fish and Game personnel and Westco Construction have been busy along the shores of Idlewild Bay, in Farragut State Park. The plan was to create additional spawning habitat for Lake Pend Oreille’s keystone species, the kokanee salmon. Kokanee are the primary food source for all of the lake’s trophy fish species, and an important component in the diet of bald eagles, osprey, and many other species of wildlife throughout the year. A combination of factors related to lake habitat and high levels of predation from larger species such as Gerrard rainbows and lake trout had reduced kokanee abundance to the point that we closed the fishery in 2000. An intensive effort to reduce predator numbers through angler harvest and netting has been very successful in increasing annual survival rates of kokanee, allowing a marked recovery of their numbers in recent years. The kokanee fishery was reopened in 2013. With the increased number of kokanee adults comes an increased need for available spawning habitat.
Through funding provided by Bonneville Power Administration, we embarked on an ambitious plan to overlay about a half mile of rocky shoreline with a suitable 4-6” layer of ¼ to ¾ in. diameter gravel. The idea was to place this new gravel below the wave-washed zone along the shoreline in an area where there was currently only large cobble and rock. A perfect location was identified immediately adjacent to the Eagle Marina boat ramp in Farragut S.P. This location would be very efficient for gravel hauling, loading, and barge travel to the work site. It was also found to contain areas of “downwelling” where lakewater was being drawn into the Spokane Aquifer. This would provide a steady flow of oxygen rich water through the gravel for eggs and fry. We marked out an area between 10 and 50 ft. deep, that equated to approximately 7.5 acres of lake bottom. The project was divided into three phases, with approximately one-third of the total area being covered in gravel each year. Within a month of each year's application, adult kokanee had moved in and begun to spawn on the newly placed gravel, offering their hearty approval to the project. The project relied on the ingenious design of the barge and gravel delivery system developed by our contractors, Westco Construction. This delivery system created a surprisingly even distribution of gravel across the work area. It required no additional blending or smoothing, and was very attractive to spawning kokanee.
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With this additional area of high quality spawning habitat, which is deep enough to be safe from future degradation by wave activity, Lake Pend Oreille’s trophy fish species, birds of prey, and anglers alike can look forward to high numbers of kokanee salmon for years to come.