The Central Oregon region covers approximately 7,833 square miles (20,290 km2), and sits at the convergence of the Basin and Range, Cascades, Blue Mountains, and Columbia River Plateau geologic regions. Central Oregon is traditionally considered to be made up of Deschutes, Jefferson, and Crook Counties.
Because Central Oregon is part of a historically volcanic region, volcanic rock formations are a common sight, including lava beds, volcanic buttes, crater lakes, volcanic plugs, and lava tubes. The native plant life of Central Oregon can be divided between the Ponderosa forests at the foot of the Cascades, and the smaller Western Juniper forests to the east, with the Deschutes River being a rough boundary between the two.
The Deschutes River is the primary river flowing through Central Oregon. Its source is Little Lava Lake in the Cascade Mountains, northwest of LaPine. The Deschutes runs south to north, eventually flowing into the Columbia River. Along its way, dams control its flow creating Crane Prairie Reservoir and Wickiup Reservoir. It is tapped as a water source for the Central Oregon Irrigation District which serves agricultural and municipal users. The two largest tributaries of the Deschutes are the Metolius River and the Crooked River. The Metolius begins at Metolius Springs and runs northeast, flowing into the Deschutes from the west just south of Round Butte Dam. The Crooked River flows west from its sources in the Ochoco Mountains. Both rivers merge into the Deschutes River, becoming part of Lake Billy Chinook, the reservoir created by the Round Butte Dam.
The distribution of people in Central Oregon occurs mainly near its rivers. Most of its towns are built on riverside plains and between their surrounding foothills. Irrigation development in the region has made its otherwise arid flatlands useful for extensive hay production, farming, and raising livestock.