Bounding and identifying issues in the Grand Canyon
From RAWorkbook
The Grand Canyon is one of the largest geomorphic features on the planet, created over the past 6-10 million years by the Colorado River. The Grand Canyon can be used to help illustrate the way in which issues of resilience can be identified and used to establish tentative bounds for assessment.
Over the past century dams have been constructed along the river in order to stabilize the water flow, generate electricity, and to provide water to the arid regions of the southwestern United States. Flood protection and water for human use (consumption and irrigation) are the primary purposes for controlling the flow of water in the Colorado River. The revenue from the sale of electricity pays for the initial capital cost of dam construction and a portion of ongoing operations, as well as environmental research and management activities. Yet the construction of the dams has resulted in dramatic changes in the ecological, social and political regimes. This region provides an example of how to begin assessing issues of resilience. That assessment should begin with identifying key resource issues, and describing the relevant geographical boundaries and time horizon.
Boundaries
The Grand Canyon is in a reach of the river bounded upstream by the Glen Canyon dam and downstream by the Hoover dam. The dams provide a way of bounding the river system for analysis, in terms of control points of key ecological processes and administration. Yet it is not easy to use these structures as bounds, because some ecological processes extent far beyond the dams, while others do no. Water, nutrients and biota all flow through the system, originating upstream, while sediments no longer nourish the Grand Canyon reach of the Colorado River.
The time horizon of assessments can be established, and are generally related to the issue being considered. The time domain is described along with each issue.
Management Issues
Prior to damming the river, it had extreme flow variation, large sediment loads that colored the water red (hence the origin of the name, Colorado River), and seasonally large fluctuations in temperature. Today, downstream of the Glen Canyon Dam, the altered river system has relatively stable flow, clearer water, and a near-constant temperature year-round. These changes in turn have had unforeseen consequences, such as the extirpation of seven species of native fish, the endangerment of four others, and a loss of habitat types. The water flows of the Colorado used to vary at time scales of months to decades, with a strong annual cycle. Currently, the largest flow variation occurs on a daily basis, associated with releases to generate electricity.
Present management challenges include how to restore sediment inputs and retain current sediments within the system. The sediments are deposited on the banks during high flows, and erode back into the water during low flows. Keeping sand on the banks is important to the large recreational community who camp on the beaches, and to the conservation of cultural artifacts along the river.
Another management issue involves the declining populations of the humpback chub and kanab amber snail. Water temperature, flow, tributary inputs, and predation by non-native fish all contribute to their continuing endangerment. Since these two species receive special protection under the U.S. endangered species act, their recovery is a primary management goal and any management action must not harm the populations. Hence mitigation and amelioration of dam effects are primary objectives of management. As such, the time frame for assessment and issue resolution is on the order of multiple decades.
The canyon has a long history of human habitation and cultural values. For thousands of years people have used the river and surrounding land. Many sites are of significant cultural and historic value where legacies of past use still persist. Maintaining these cultural sites is another concern of managers.
The management of the Colorado River and Grand Canyon involves a complex of institutional structures and processes. A number of laws and treaties lay out rules for allocation of water among the various users. The federal government is represented by half a dozen management agencies, including the Bureau of Reclamation, National Park Service, U.S. Fish and Wildlife Service and Bureau of Land Management. Several native American tribes also participate in management decisions about the river and surrounding areas. At least six states participate in the management of this reach of the river. Non-governmental organizations represent conservation interests in the river, recreational and guide fishers, and rafting and boating groups, among others.
The institutional components of managing the Grand Canyon portions of the Colorado have become more integrated. That is, some groups are engaged to protect the ecological values of the system, such as the US Fish and Wildlife Service that has responsibilities for threatened and endangered species. Similar non-governmental organizations exist, such as the Center for Biological Diversity. Other groups, such as the Western Areas Power Administration, organization of Fly fishers, or the River Rafting associations represent economic features of the system. Other groups or agencies such as the US Park Service, Bureau of Reclamation have missions to integrate the ecological, social (including cultural), and economic dimensions of resource issues.
