Abstract The Milton Roswell Trenam papers (1925-1932) consist chiefly of research reports concerning the Coolidge Dam irrigation project on the San Carlos Indian Reservation, Gila County, Arizona. Included is an announcement featuring Roy Rodgers who dedicated the Coolidge Dam. Milton Roswell Trenam was a graduate of the University of South Dakota who worked for the Bureau of Indian Affairs as a construction engineer. He designed the model for the Coolidge Dam.