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The 1984 flood threatened the Gibson's Department store located on the left overbank on the Gunnison River immediately dm;nstream of the Highway 50 bridge. Floodfighting prevented significant damage. The emergency dike prevented inundation of much of the undeveloped proposed commercial area at Confluence Park" A large portion of the confluence of t:he rivers experienced im;ndation. Local officials reported that the confluence of the channels was shifted to t:he north as a result of the 1984 flood. Field inspection confirmed that the channels fcr both rivers near the confluence have shifted. ConCErn exists for an area of bald eagle habitat and for a propesed trail system, both close to the riverbanks, sheuld the river channels shift: again. The new sEwage treatment plant on the Gunnison River downstream of the confluence was almost surrounded by water in 1984. In ac,dition, the right bank of the river had to be armored as an E'mergency measure due to the "threat of breakout and ce,nsequent channel meander in "I:he vicinity of the treatment plant. The draft lOa-year and the 500-year flood plains, as delineated by the Sacramento District in 1989 for the Gunnison River only, are shown on Plate 4-1. These delineations, I,erformed for the Federal Emergency Management Agency, were be,sed on the peak flows for th,= Gunnison River as described iT. the FEMA 1983 Flood Study. The old flood plains for the Gunnison and Uncompahsrre Riv,=rs, as presented in the FEMA floodway maps dated 1984, are also shown on the same plate. It should be noted that the revised flood plain for the Gunnison River shows the proposed fish ponds and a significant portion of the proposed industrial-commercial area within the lOO-year flood plain. The new delineations follow FEMA criteria which call for any diking not having a 3-foot freeboard for the lOO-year flood, or being structurally iT'sufficient, to be considered as a breached structure. ThE' revised flood profiles for ithe Gunnison River show the lOa-year flood along the bulk of the Confluence Park to be higher (in some places a little over a half foot) thaT' shown in the 1983 Flood Insurance Study. These reasons account for much of the difference between the old and revised flood plain delineations for the Gunnison River. 5. Hvdroloqv. The Federal Emergency Management Agency's Flood Insurance StUdy, dated September 15, 1983, contains the peak flows for the lO-year, 50-year, laO-year, and 500-year floods on the lncompahgre and Gunnison Rivers. The flow-frequency values for the Gunnison RivE!r were revised in 3