Crane Prairie Dam was built by several local irrigation districts serving lands south of the North Unit, principally the Central Oregon Irrigation District. It is a rockfill timber-crib dam about 2 miles above Wickiup Reservoir on the Deschutes River. By the time work began on the North Unit, the dam had become unsafe and was rehabilitated by the Bureau of Reclamation in 1940. Crane Prairie Dam is an earthfill structure 36 feet high and 284 feet in length at its crest. It contains 30,000 cubic yards of material. The spillway is an uncontrolled weir in the floor of an open cut channel in the left abutment. The reservoir has a total capacity of 55,300 acre-feet (active 55,300 acre-feet).
The right wall of the spillway was raised 9 feet in 1992 to enable passage of 60 percent of the probable maximum flood without overtopping the dam.
Crane Prairie Dam and reservoir are situated in forest covered volcanic mountains, consisting of buttes, craters and intervening sediment covered basins. The intermittent out-pouring of lava flows and explosive volcanic activity has created very complex geologic situations in local areas. The porous lava flows, breccia, ash and deposits of water lain sediment can be linked to a huge absorptive sponge with local perched or depressed water tables, where lakes and springs have been created at various elevations, according to the rate of inflow or outflow of water as it adjusts to local topographic and geologic conditions. The readjustments of the earth's crust during and following volcanic activity undoubtedly created huge cracks, fissures and faults through which the surface water can be lost or move to lower subsurface elevations.