Riparian habitat changes in Cibola National Wildlife Refuge: 1959-1991

Abstract

In 1959, the Bureau of Reclamation proposed a channelization project through the Cibola Valley along the Lower Colorado River. The project entailed rerouting the river through a dry cut in order to lower groundwater levels in the Palo Verde Irrigation District upstream, thereby improving irrigation drainage. In conjunction with this, Cibola National Wildlife Refuge was created in 1964 to mitigate the effects of habitat loss from the channelization project. Aerial photographs of the Cibola Valley were analyzed for 1959, and vegetation community types were determined. A vegetation type map was developed for 1959 and compared with vegetation type maps for 1976 and 1986. Between 1959 and 1986, a lowering of the water-surface level in some parts of the refuge resulted in the draining of some lakes and the creation of slow-moving backwaters. Cottonwood-willow and marsh communities saw a significant reduction in area while the salt-cedar community saw rapid growth.