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Conclusions
Human populations are, of course, a valid and participatory component of the Earth's ecosystems, and they are also the only living creatures capable of substantially and intentionally altering an ecosystem for their own immediate uses. In spite of this capability, humans are, nevertheless, dependent on the altered ecosystem of their own creation. There is convincing historical documentation of technologically advanced nations and empires that disappeared largely because of their unsustainable dependence on limited water resources. That water is, indeed, a limited resource has been acknowledged by both California and in specific areas of Arizona by requiring developers to demonstrate the existence of a 100-year assured water supply before building structures requiring water service. The primary conclusion of the Colorado River Task Force is that the current usage of the Colorado River is unsustainable. The existing plumbing system is vulnerable to natural events, such as sustained drought or earthquakes, as well as to engineering failure. Reconstructed histories of the region strongly suggest that prolonged droughts, several times longer than those experienced in the last 150 years, are real, although irregular, features of what is now the southwestern United States (8). Seismic activity is vigorous in the westernmost segment of the area and occasional in other sections. An example of this seismic threat is shown by the curtailment of the Paradox salinity control project in southwestern Colorado due to increased seismic activity - 3,000 tremors since 1991 - and a recent increase in magnitude. Failures are not uncommon in complex systems, because the intricacy of the systems leaves them vulnerable to relatively small engineering errors, construction inadequacies, or materials failure. The vulnerability of the Colorado River plumbing system directly jeopardizes the ability of the region to support its human population over the long term, a threat of national and international importance. Southern California is a major urban and agricultural area and the center for numerous economically important industries. Even partial collapse of the regional plumbing system would threaten the continued economic health of California, perhaps catastrophically, and California alone is the eighth greatest economic entity in the world. Ironically, Colorado River water that has been absolutely necessary for the unbridled growth of the region is now so oversubscribed and overallocated that it poses a threat to the region's continued economic vitality. The currently overstressed Colorado River system, which has only a limited margin of safety, threatens more than the human populations of the ecosystem, although in some cases with less predictability. Before the human population mushroomed, the river was populated with native fish highly adapted to uneven water flow and episodic drought; the riparian and wetland areas, most importantly the vast Colorado River Delta, provided important habitat to wildlife and millions of resident and migratory birds, and the Sea of Cortez was a productive ecosystem providing food for man and wildlife. Native fish are threatened, endangered, or on the way to extinction; many native plants are at a disadvantage to invasive foreign competitors; bird habitat in the Lower Basin is limited to small, often overcrowded and polluted, enclaves; and the Sea of Cortez is starved for the nutrients that were once provided by the freshwater river. All these problems are the consequences of unbalanced allocation of a critical natural resource, the water of the Colorado River Basin. In a region that is drier than the deserts of North Africa, water is the limiting factor for the support of life. Three related factors, all of which are manmade, are to blame for all the problems threatening the wildlife of the river basin - too little water in the river, high flows at the wrong time of the year, and too much nutrient-laden silt trapped behind a plethora of dams. These same factors have also stayed the hand of nature in its millennia-long sculpturing of one of the most impressive landscapes in the world. Canyon erosion, beach and sandbar deposition, and the cyclical appearance and disappearance of vegetation and wetlands have all been slowed or stopped. Although the catalog of problems with the Colorado River and its tributaries can seem overwhelming, there are many indications that prudent, preferably immediate, changes in the way the water is allocated could ameliorate most or all of the problems. There are limits to the human population that can be supported, but growth could continue for many years, if the water were used more wisely. Similarly, it is not possible to reverse all the environmental destruction, but it is possible to stop the destruction and reclaim or restore many key areas and, with some measure of luck, the native fish. (8) Meko, D., Stockton, C.W., and Boggess, W.R. 1995. The Tree-Ring Record of Severe Sustained Drought. Water Resources Bulletin 31(5): 789-801. Photo: Canals, Colorado River Reservation, Parker, AZ. Copyright Stephen Trimble. Report Main | Background
| Conclusions Up to Top |
The Colorado River that met John Wesley Powell on his
journey through the southwest was a sometimes roaring, sometimes placid, waterway that
supported a variety of native fish and a rich riparian and riverine ecosystem in the midst
of desert. The erection of dams, reservoirs, and canals, along with countless diversions,
has turned the river into a plumbing system, and today, the Colorado is a river no more.
The once vibrant ecosystem is in most places but a feeble ghost of its former glory.
Indeed, much of the present ecosystem is manufactured, where hatchery-raised non-native
fish, exotic plants, and agricultural crops dominate the living world of the Colorado
Basin, along with some 20 million agents of change, the human population.