John Day, river, 281 mi (452 km) long, rising in several branches in the Strawberry Mts., NE Oreg., and flowing W, then N to the Columbia River. Unnavigable, the river is used to irrigate vegetable farms. Within the river valley is the John Day Fossil Beds National Monument, containing well-preserved fossils of plants and animals (see National Parks and Monuments, table).
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.