Central Oregon's Geology And How It Affects Water Supply
How Volcanoes Affect the Basin
In the Deschutes River Basin, volcanic geology controls everything from channel shape to water temperature to summer flow levels. The volcanic rock in the region is also responsible for regulating the temperature and flow levels in the Deschutes River throughout the year. Because the rock is so porous, it absorbs a lot of rainfall and snowmelt, releasing it into the river at a slow rate over the course of the year from underground springs. The water from these springs stays at a nearly constant temperature and keeps a low level of flow (known as ‘baseflow’) in the Deschutes and its tributaries regardless of how much rainfall or snowmelt is occurring. These baseflows are very important for fish, especially those which depend on having cool pools to over-summer in (like steelhead).