Permafrost is melting all over Alaska as a result of rising temperatures, causing land underneath many villages to subside and softening the soil on riverbanks like the mighty Yukon River.
Mountain snow and ice melt rapidly, causing a short period when water levels in the rivers rise and move rapidly. The high, fast flowing water serves to wash away an unprecedented amount of riverbanks in villages.
The vast amount of soil taken into the river causes riverbeds to rise as eroded soil accumulates on the bottom.
River depths decrease to the point where many areas are so shallow that more and more salmon that are caught in subsistence fishing have lesions, cuts, and scrapes as they struggle to get through very shallow parts of the river.
The low levels that remain for the rest of the summer mean the water is warmer than in the past, causing further stress to the fish during the breeding season.
It may come to the stage that salmon numbers will dramatically decrease within the foreseeable future. This in turn will affect the food available for bears, land otters, eagles and people.
Less salmon carcasses taken inland and left near the rivers will decrease the fertility of land, water, and vegetation. Most "mainlanders" do not understand that we are talking about millions and millions of salmon taken by wildlife every year in Alaska, so the loss of salmon will have significant ecological impacts to land, water, wildlife and vegetation.
There are quite a lot of things that most mainlanders don't understand.