Organizing for Endangered and Threatened Species Habitat Draft

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? ? ? ? ? erosion and deposition (Outwater 1996: 57-58). River backwaters, oxbows and chutes in a ? meandering pattern were important to breeding, feeding and resting habitat for resident and ? migrating waterfowl such as sandhill and whooping cranes, ducks, geese, and a variety of shore • birds including the least tern and piping plover. Flood pulses re-worked stream channels by • clearing out woody vegetation and flushing out silt accumulated in interstices of gravel beds renewing sites of fish hatcheries. Most aquatic productivity has occurred in floodplains rather than in the main channel (Outwater 1996) The transitional zone between river channel and prairie grasslands acted as a buffer from the extremes of flowing water and arid uplands. Successive plant/animal communities occupied meander loops as they were slowly transformed from aquatic channels to isolated oxbows and finally to wet flood plain depressions. As long as the river system kept creating new loops and cutoffs a succession of habitats suited to each type of ecological community was maintained-i.e. the larger river and floodplain sustained all stages of the process and did therefore support a rich diversity of life. Deterioration of Habitats The Platte river basin has been impacted by 15 major dams and reservoirs that are supplemented by many smaller water diversion and storage projects. There are 106 storage facilities on the South Platte alone holding an average of 2.8 million acre-feet of water (Eisel and Aiken 1997). Upstream from Lake McConaughy on the North Platte River, there are 84 storage works with a capacity of 4.3 million acre-feet. The total basin storage capacity is about 6 times the average annual flow of the Platte at Grand Island. Dams and reservoirs in the Platte River Basin provide a total storage capacity of over 7.1 million acre feet, with the Bureau of Reclamation projects accounting for 2.8 million acre feet (Keys 2002). Traditionally river diversions were primarily for agricultural use, but higher value-added uses in the urban, industrial, and post-industrial high technology and recreational sectors have pulled water out of agriculture at a rapid rate. All of the hardware that social organizations have put in place in the Platte basin has produced wealth that rides with hydroelectric power, urban and industrial development, wetlands and wildlife for species benefitting from dense riparian vegetation, increased late summer, fall, and winter season base flows, recreational boating and other water sports that are served by reservoirs, and outstanding cold water fishing below dams. On the cost side of the ledger, however, the Platte in many places has become a stream of narrowed channels intersected by densely vegetated islands and flood plains, destruction of oxbows and meanders that in turn undercut natural wetlands, fish migrations blocked by dams, growth of woody vegetation no longer swept away at the seedling stage by naturally occurring flood pulses, and highly variable temperature fluctuations as cold lake bottom waters are periodically released. In general, the traditional flow regime has been changed to one characterized by lower and less frequent spring flood pulses, clearer water flows as sediment was trapped behind dams, more incised straighter channels, and higher mid-to-late summer, fall, and winter flows.