At LandWatch and Great Old Broads' educational event regarding the Deschutes River, Professor Daniele McKay explained the geological underpinnings of Central Oregon's water systems.
We learned that in the Deschutes River basin, groundwater and surface water are one. Precipitation in the mountains soaks into the ground and becomes groundwater, then reemerges as springs that feed the creeks and rivers.
We also learned how current practices are causing the Upper Deschutes River to be dewatered in the winter months and flooded during the irrigation season.
The authors of the 1947 Oregon State Game Commission report documenting the impacts when flows below Wickiup were decreased to 50 cfs wrote,
"It was determined during this investigation that 300 second feet of water are necessary to cover the whole bottom of the river. However, in view of the need for a large amount of irrigation water, it is believed that 200 second feet would be a reasonable compromise on the level below which the Deschutes should never be allowed to drop." (p. 3)