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1 ~. <br /> <br />Related Studies and Information <br />The technical information that was used during the CWC$ review include the following <br />items: <br />• Flood Hazard Information Study, Dolores River and Tributaries, bolotes, Montezuma <br />County, Colorado. U.S. Corps ofEngineers, Sacramento District, September 1978 <br />• Flood insurance Study, Montezuma County, Colorado (Unincorporated Areas). <br />Federal Emergency D4anagcment Agcney, May 4, 1989. <br />• Aerial photographs, Dolores River valley, photo numbers 12-1, 13-2, & 15-2 from <br />project number 77-208, dated 5/31/77. <br />• Aerial photograph numbers DLR-6-109 through 115 dated 8-5-96. <br />• Affidavit of Dr. Robert W. Blair, Jr. Ph.D. before the Department of Natural <br />Resources, Colorado Mined Land Reclamation $oard. <br />• November 2001 Discussions with Mr. Dale Hatch, Chief, Floodplain Management <br />Ser+•ices U.S. Corps of Engineers, Sacramento District regarding the Hydrology and <br />Hydraulics Determinations for the September 1978 Floodplain Report. <br />e Peak 5treamtlow for USGS gaging station number 09166500, Dolores River at <br />Dolores, Colorado dated 11-OZ-2001. <br />• Floodplain Resolution Number 00-525 dated September 25, 2000 for Flood Insurance <br />Study, Montezuma County, Colorado, dated May 4, 1939. <br />"I'cchnioat ltcviety Findings <br />The CWCA revie+v is based on an evaluation of available information and a Feld <br />-inspection of sites 1, 2, and 3 as shown on the location map (map 1). No new field <br />surveys and mapping were obtained, and no new hydrologic or hydraulic modeling vvas <br />performed for the CWCB review, It was observed during the field inspection that the <br />basin conditions, topography, and runoff characteristics have not substantially changed <br />since the time when the CtVCB and Corps of Engineers originally completed the Flood <br />Hazard Inforn,ation Study during 1977 and 1973. The engineering information in the <br />Carps report +vas utilized for the official Montezuma County, Colorado Flood Insurance <br />Study dated May 4, 1989. The 1OO•}'car toodplain in the Corps and FEMA studies is in <br />fact the designated floodplain for the Dolores River in Montezuma County, Colorado. <br />The CWC$ revic+v focused on the follotivirg enginccring considerations only: <br />1. Base topographic mapping and ticld surveys <br />2. Hydrologic analysis <br />3. Hydraulic analysis <br />Q. 100-year floodplain delineation <br />5. Stream and channel geomorphology <br />6. Gravel pit vperatinns impact to the designated 100-yr floodplain <br />grief descriptions ate provided below for each of the review categories listed above. <br />I. Base Mapping and Sun•eys: The CWC$, in cooperation with Montezuma County, <br />contracted the professional mapping services of Benchmark Mapping 5ervic'cs of Denver, <br />Colorado to compile detailed large mapping of the Dolores River channel and floodplain <br />in 1977. The mapping and surveys were prepared to "National Map Accuracy Standards" <br />for 2' and 5' contour mapping. The mapping project set control markers and monuments <br />EO!-d Bl0/El0'd 05E-1 955E99EEOE <br />S3JHf1053b 1V8111tlN 100-Yi01id 9l~ll E002-VD-03D <br />