The Arizona Capitol Times published an detailed explanation (subscription needed) of the issues at stake in the legal fight over the city of Prescott's plans to pump water from the Big Chino Water Ranch.
The key argument by opponent Salt River Project (SRP) is that "the cone of depression that would be created at the Big Chino Water Ranch would reach the sub-flow zone of the Verde River, which is subterranean water that finds its way into the river and is legally considered part of the river."
However, they note that the Arizona Dept. of Water Resources denied that claim during the review process on Prescott's proposal. ADWR certified the Big Chino will meet the state's requirements for a 100-year assured water supply.
SRP and others appealed ADWR's approval of the project. Administrative hearings started in January and are now expected to continue into June or later.
AZGS is mapping Holocene-aged sediments along the Verde River for ADWR for adjudication purposes.