The Agricultural Extension Service was a cooperative project of the University of Arizona, College of Agriculture, and the U.S. Department of Agriculture, which encouraged agriculture and home economics in Arizona. 

The collection includes records on printed forms, as well as data on wells and pump irrigation for Townships 9-21 in Pima County, AZ from 1912 to 1941, including records of stream flow in Santa Cruz River, Rillito Creek, and Sabino Canyon, from 1904 to 1935.