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<br />Section 1 <br /> <br />Related Studies <br /> <br />Two major flood hazard identification studies were used to determine flood risks at each of the <br />8 ponds. One study is the Flood Insurance Study, Mesa County, Colorado, Unincorporated <br />Areas, revised July IS, 1992 (FIS). It was prepared after the 1984 flood on the Colorado River <br />to update floodplain delineations in the Grand Junction area. The contractor's scope for that <br />effort also included revisions to the Flood Insurance Studies (F ,I.S.') for Palisade, Grand <br />Junction, and Fruita, but those other studies were not used for this report. In addition to the FIS <br />itself, the CWCB staff used the Hydrology Report, Flood Insurance Studies in Mesa County, <br />Colorado, dated May 1989 prepared by J.F. Sato & Associates, Inc. as part of the FIS revision <br />contract and the topographic mapping used to delineate the floodplain boundaries. <br /> <br />The other study has not yet been published. When it is published, it will be entitled Floodplain <br />Information Report, Colorado River from Glenwood Springs to DeBeque Canyon, Garfield and <br />Mesa Counties, Colorado. The Sacramento District of the U.S. Army Corps of Engineers is <br />working with the CWCB to map the floodplain of the Colorado River from Glenwood Springs <br />downstream to the upstream (east) end of DeBeque Canyon. Preliminary floodplain maps have <br />been prepared, but there is no final report at this time. CWCB staff used two sets of related <br />documents: I) The 1985 Hydrology Report prepared by the Corps of Engineers and 2) The <br />topographic mapping prepared with funding from the Colorado Department of Local Affairs for <br />the floodplain identification effort. A third related document is a report prepared for the Town <br />of Parachute by its own private consultant. Floodplain Information Report, Parachute Creek, <br />Colorado River in the Town of Parachute, Colorado, prepared in October 1989, delineates the <br />floodplain of Parachute Creek and the Colorado River in and around the town. The report used <br />the unpublished Corps of Engineers information for the Colorado River. <br /> <br />There is a gap of about 12 river miles between these two studies. Floodplain maps were not <br />prepared for the DeBeque Canyon. Because there is not a great deal of existing development or <br />development potential in that canyon, it was left out of the scope of both studies. Island Acres <br />State Park is in DeBeque Canyon, so CWCB staff had to approach that site differently than the <br />other sites. The hydrologic and hydraulic analyses for Island Acres will be described later in this <br />report. <br /> <br />In addition to the two floodplain studies described above, CWCB staff used other sources of <br />information. Survey control information provided by the Mesa County Surveying Department <br />facilitated field surveys. Engineering information prepared for the City of Rifle by Schmueser, <br />Gordon, Meyer delineated the changes to the floodplain caused by the Colorado Department of <br />Transportation's 1-70 Rest Area at Rifle. The Town of Parachute provided historical information <br />and aerial photography of the flooding at the Parachute Pond in 1983 and 1984, Colorado <br />Division of Parks and Outdoor Recreation staff provided information about historic flooding at <br />their facilities (Com Lake and Island Acres State Park). DOW staff provided aerial photography <br />of all of the ponds during the 1993 flood. <br /> <br />4 <br />