Platte River Tributaries Nebraska

This report presents the results of the Corps of Engineers' Section 22 study of ice jam flooding in the Lower Platte River basin. The purpose of the study was to gather and analyze historical data relating to ice jams, with the intent of developing guidance that can be used to alleviate ice jam flooding at seven sites within the study area. Ice event and related information is summarized for each site. Ice event characteristics for the study area are identified and analyzed. A model for predicting the occurrence of ice jams or other ice events within the study area was developed based on data for the Platte River at North Bend, Nebraska. The model provides the minimum discharge associated with ice events for a given date, assuming a threshold value of accumulated freezing degree-days has been reached. A data collection program for future field observations was developed and placed in operation during the winter of 1993-94. General information on ice jam mitigation measures, as well as specific information on such operations as dusting and blasting, is provided. Specific recommendations include increased monitoring of ice conditions, installation of ice motion detectors and water stage recorders, and further study of nonstructural and structural mitigation measures. The use of dusting and blasting as mitigation measures is also presented. The study was divided into six phases. Phase 1 involved collection of historical information from all available data sources, published and oral. Site visits were made to each identified site. Phase 2 entailed analysis and assessment of the collected hydrological, hydraulical, meteorological and ice data.

The tension between wildlife protection under the Endangered Species Act and water management in the Platte River Basin has existed for more than 25 years. The Platte River provides important habitat for migratory and breeding birds, including three endangered or threatened species: the whooping crane, the northern Great Plains population of the piping plover, and the interior least tern. The leading factors attributed to the decline of the cranes are historical overhunting and widespread habitat destruction and, for the plovers and terns, human interference during nesting and the loss of riverine nesting sites in open sandy areas that have been replaced with woodlands, sand and gravel mines, housing, and roadways. Extensive damming has disrupted passage of the endangered pallid sturgeon and resulted in less suitable habitat conditions such as cooler stream flows, less turbid waters, and inconsistent flow regimes. Commercial harvesting, now illegal, also contributed to the decline of the sturgeon. Endangered and Threatened Species of the Platte River addresses the habitat requirements for these federally protected species. The book further examines the scientific aspects of the U.S. Fish and Wildlife Service's instream-flow recommendations and habitat suitability guidelines and assesses the science concerning the connections among the physical systems of the river as they relate to species' habitats.