Synthesis and Management Implications of the Colorado River Research Program

Grand Canyon National Park, Arizona
Colorado River Research Program

September 1977

ABSTRACT

Scientific data on the riparian and aquatic ecosystems of the Colorado River in Grand Canyon National Park were collected from 1973 through 1976. The Colorado River Research Program emphasized investigations of human uses and interrelationships between sociological, biological, physical and chemical parameters of the riverine ecosystem. In some situations environmental degredation exceeded the system's capacity to adjust and therefore irreversible changes were occurring under existing use patterns. Impacts were a result of the increasing numbers of river recreationists and, primarily, the altered riverine regime produced by the operation of Glen Canyon Dam. Major environmental impacts identified included: scouring and loss of natural river bed; loss of beaches through erosion; spread of exotic plants and vertebrates; trail proliferation and vegetation trampling; incorporation of human litter, waste and charcoal into beach deposits; and wildlife utilization of artificial food sources.

Sociological analysis of river users revealed user attitudes, and back-ground, crowding variables, and degree of wilderness perception. Most users perceived the canyon as uncrowded at present use levels. Private and commercial users differed on a number of background variables, with most users defining their trip in terms of wilderness through a preference of non-motorized travel. Economic analysis of float trip concessioners revealed the profitability of river concessions as well as indicating that total conversion to oar travel is economically feasible. The effects of motor noise on the visitor's experience is discussed.

Status and distribution of mammals, birds, reptiles, amphibians, fishes, insects, vascular plants and aquatic micro-organisms are outlined. The Grand Canyon was considered by several biologists as one of the last remaining refuges for several species of endangered fish which flourished in the Colorado River prior to construction of Glen Canyon Dam. Physico-chemical data for the river indicates the development of a more stable system than existed before construction of the dam leading, in part, to increased recreational use. Recommendations to management and future research and monitoring needs are discussed.

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