In response to the posts
Bill Lenihan has provided us with further insight into the role of dams on climate.
The Consequences Of Damming The Columbia River by W. F. Lenihan
The following anecdotal information and facts about the consequences from damming the Columbia River are consistent with the study, “The influence of large dams on surrounding climate and precipitation patterns“.
The city of Wenatchee, WA, is at the confluence of the Wenatchee River with the Columbia River in Chelan County. Before any dams were constructed, the Columbia River froze most winters in this area. My deceased father-in-law’s family settled in Wenatchee in 1896. They planted and farmed orchards around their home. The residents cut ice from the Columbia, stored it, and used it for refrigeration until the area was electrified.The weather changed after the construction of the dams in the vicinity of Wenatchee.
The first dam, Rock Island was built a few miles downriver from the city and became operational in 1933. It was later expanded in 1953 and 1979 to its 2600 MW capacity. The Columbia stopped freezing above and below the Rock Island pool in the mid-1930s.
The massive impoundment behind Grand Coulee Dam influenced weather throughout Eastern Washington in several ways. It provided a source of warmer water that flowed downstream from its spillways. During winters, this water moderated the ambient temperature and made freezing more difficult.
Another dam, Rocky Reach, is a few miles upriver from Wenatchee and became operational in 1961, and it was later expanded capacity in 1971 to its 1287 MW capacity.
Before these dams were built winter ground fog was rare. Since then, it is common. Commercial air service to Wenatchee and other locations along the River can be problematic at times during the winter.
The succession of Columbia dam pools have led to significant climate modification in eastern WA and OR. The only remaining free flowing segment of the River, other than a few miles between the Canadian border and Lake Roosevelt, is the 45 miles that is the Hanford Reach National Monument. Hanford Reach is between the Priest Rapids Dam upriver and the McNary Dam downriver.
Another facet of weather modification is the water from the Grand Coulee reservoir, Lake Roosevelt, and later from the Chief Joseph Dam, was used to reclaim much of the Columbia River Basin from desert into some of the most productive irrigated farm lands in the world.
I am sure that there is a wealth of weather records available from stations along the Columbia for data before and after the dams that supports and augments existing research on the subject.