Threats to Wildlife and the Platte River

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p. 36 WILDLIFE In other words, Boudreaux adopted the flow rate from Karlinger et al.'s example and tried to calculate the number of days of 3,800 cfs flow which would, over the course of a year, cumulatively equal the total amount of water which had annually occurred during flows greater than or equal to 3,800 cfs since 1950, a period during which flows were much lower than historic levels and the channel was not in equilibrium, but, rather, slowly deteriorating. Boudreaux's assessment of his own flow management plan is that it "should be adopted as an objective or target, so as to maintain the habitat in a reasonably acceptable condition" (p 19). Boudreaux's numerous judgments and calculations, from which he derives his flow management plan, are used (and his report is extensively quoted without proper reference) by the FWS (for whom the report was done) in their Narrows Unit Biological Opinion (1983). Boudreaux's report was also a source used by the Nebraska Game and Parks Commission in their Little Blue - Catherland Biological Opinion (1985a) and Twin Valley Biological Opinion. Not surprisingly, these numbers agreed closely, since Boudreaux's report was heavily depended upon in both opinions. It often seems that these numbers are cited due to lack of alternatives. For example "While the specific instream flows required to maintain the required habitat conditions are the subject of additional study, those flows recommended by the Nebraska Game and Parks Commission [1985a] are used as target flows in this plan formulation" (Platte River Trust 1985, p 8). The Corps of Engineers (1986) refers to "the 3800 c.f.s. criterion, established by the U.S. Fish and Wildlife Service in the Narrows Opinion" and to the 1100 cfs flow discussed in the same opinion (see footnote "L "). Uncritical acceptance and use of these numbers in models and forecasts may yield faulty conclusions. Yet these numbers are in fact used in models; for example, in the NGPC evaluations (Shen et al. 1985, p 23). J Authors examined aerial photos of three sites at differing, flows and counted the number of channels that were 50, 75, and 150 meters wide. K However, a more conservative interpretation of Krapu, et al. (1984) is possible that would not consider channels that are less than 100 meters wide to be adequate. Krapu et al. found that 82 percent of the channels were wider than 50 meters, and that 99 percent of the Sandhill Cranes were in these channels. However, only 25 percent of the river segments were greater than 150 meters wide, yet 70 percent of the Sandhill Cranes roosted in these wider stretches, indicating strong preference for channels wider than 150 meters. L This number first appeared in Boudreaux's report, using information supplied by Gene Miller of FWS' Grand Island Office. FWS rationale was that "in almost all cases (when Whooping Cranes utilized the river), the flows were 1100 cfs or more. It is FWS's opinion that flows of 1100 cfs in the river between Overton and Grand Island should be adequate during the migration period, if vegetative encroachment is controlled" (USFWS 1983, p 22). Note that the Fish and Wildlife Service recommended a stream flow that was less than what the flows actually were while the birds were using the river. M Discussion of the 1,100 cfs flow in relation to wet meadows first appeared in Boudreaux's report, using information supplied by Gene Miller of USFWS' Grand Island Office. Although wet meadows continue to decline, no data are provided by Boudreaux or FWS in support of the idea that flows of 1100 cfs beginning February 1 "were considered necessary to initiate bio- logical response in wet meadow vegetation and invertebrate populations before the cranes arrive" (Boudreaux 1982, p 5). Although Boudreaux stated "the tolerance of the wet meadows to changing hydrologic conditions is still not very well understood, so it is difficult to assess just how adequate the 1100 cfs flow might really be... The wet meadows farther from the river