I am a climate scientist. My research at Pacific Northwest National Laboratory (from which I am retired) estimated a 70% reduction in the average mountain snowpack in the western U.S. by the end of this century, for a carbon emissions scenario like the path the world is on today.
Since 70% of river flow in the western U.S. is from snowmelt, such a loss of snowpack implies a 50% reduction in average western U.S. river flow during the dry summer months.
The impact on water supplies would not be as severe for heavily dammed rivers such as the Columbia , but its tributaries such as the Yakima, which have insufficient storage capacity to ride out the seasonal cycle in precipitation, will suffer chronic shortages of irrigation water during the growing season, unless more aggressive action is taken to reduce the global emissions driving climate change.
Moreover, the loss of mountain snowpack means mountain soil dries sooner during spring and summer, leading to a longer and more intense wildfire season…