I saw on USGS website that there were Golden Trout caught in Pass Lake in Custer County as recently as 2011. Does Idaho F&G still stock these waters with Golden Trout and does this lake tend to experience a lot of winter kill?
We stock Golden Trout in select high mountain lakes as the fish become available. California Dept. of Game and Fish, every few years, have Golden Trout eggs that are excess to their needs. When that happens, they make them available to other western states including Idaho. Idaho has tried on a couple of occasions to develop their own egg source but it has proven to be too expensive for the small number of eggs (less than 100,000) we need for our mountain lake stocking program.
Mountain lake winter-kill of fish are difficult to predict. As you would guess, drought years followed by sever winter conditions can lead to complete freezing and loss of a fish population. The other condition that will cause a mountain lake to winter-kill is when a lake has a high organic load from plant growth; freezes early; becomes snow-covered and remains that way for longer than a normal year. As the organic matter decays it uses oxygen from the water and creates what's called an anoxic condition. Trout require a minimum of 4 parts per million in the water to survive. Under certain conditions, plant decomposition has lead to 2 or less parts per million oxygen in some high elevation lakes.