I need to know how muskrats and beavers adapt upstream of a hydro dam from irregular water fluctuations. In a natural river flow here, the water get very high in September, then flushes itself out before it will freeze over in early November. After that, the river level will lower over the winter creating some shelf ice. Hydro dams will let the big water flush out in the fall but only to a point when they need to retain a certain level for winter use for hydro power. This water retention coincides with freeze up, then this controlled water will begin to lower gradually over the winter as power demand is needed.

Soon after water usage begins to recede sometime in November, air space under the main ice begin to form. By the end of the winter, the river ends up rock bottom with a huge air space under the shelf ice.

Soon as the ice form in November, this is the time muskrats build their pushups and likely abandon soon after due to the air space impeding them to reach their pushups. I hope to capture this fall during a pushup survey with a spear.

So far, I only found researches done downstream of hydro dams.

Thanks so much

Rene