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Chapter 3- Description of the Alternatives <br />%"Annual pulse flows" and "peak flows" are flows in excess of species flows that are needed to <br />help maintain the variety of ecological processes of the river channel and adjacent low areas to <br />provide favorable physical, chemical, and biological conditions for the species (including a <br />wide channel generally free of vegetation, adjacent backwaters and wet meadow areas, etc.). <br />Species Flows <br />Species flows were established as recommended "wet year," "dry year," and "normal year" minimum <br />flows for various periods of the year (for example, from February 1 through March 22) far the purpose of <br />sustaining the species and their habitat. The species flows are summarized in table 3-3. <br />Table 3-3.-Species Flows at Grand Island (cfs) <br />Period Wet year* Normal year* Dry year* <br />January 1- January 31 1,000 1,000 600 <br />February 1-March 22 1,800 1,800 1,200 <br />March 23 - May 10 2,400 2,400 1,700 <br />May 11 - September 15 1,200 1,200 800 <br />September 16 - September 30 1,000 1,000 600 <br />October 1-November 15 2,400 1,800 1,300 <br />November 16 - December 31 1,000 1,000 600 <br />*"Wet years" are defined as the wettest 33 percent," dry years" as the driest 25 percent, and "normal years" all others. <br />Adequate flows at the times of the year shown in table 3-3 are expected to provide multiple benefits to the <br />river ecosystem and the target species. Table 3-4lists some of the expected key benefits of species flows. <br />Table 3-4.-Key Benefits of Species Flows <br />Period Ke Biolo ical Benefits of S ecies Flows <br />January 1- January 31 Promote the winter survival of native fish community and aquatic insects. Provide foraging <br /> habitat for bald ea les and other ra tors. <br /> Provide migrating waterfowl and other bird species with suitable migration habitat at a time <br />February 1- March 22 when other nearby wetland habitats may be frozen. Form and move ice, which scours <br /> ve etation and sha es the channel. <br /> Provide whooping crane night roosting habitat. Provide channel habitat for water- <br />March 23 - May 10 dependent organisms, induding spawning fish, mussels, and migratory waterfowl, wading <br /> birds, and shorebirds. <br />May 11 - September 15 provide shorebird nests with a degree of protection from terrestrial predators. Protect native <br /> fish communities from losses due to hi h water tem eratures. <br />September 16 - September 30 Maintain and prevent loss of the native fish community and promote survival of fish young- <br /> of- ear. <br />October 1- November 15 provide fall migration and roosting habitat for migratory bird species, including the <br /> whoo ing crane. Maintain a uatic life (e. ., romote growth of young-of-year fish). <br />November 16 - December 31 <br />I <br />Maintain habitats necessary to support fish communities. Provide bald eagle feeding habitat <br /> and o ortunities.