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<br />Related Studies and Information
<br />The technical information that was used during the CWCB review include the following
<br />items: '
<br />. Flood Hazard Information Study, Dolores River and Tributaries, Dolores, Montezuma
<br />County, Colorado, U.S, Corps of Engineers, Sacramento District, September 1978
<br />. Flood Insurance Study, Montezuma County, Colorado (Unincorporated' Areas).
<br />Federal Emergency Management Agency, 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 Board,
<br />. November 2001 Discussions with Mr, Dale Hatch, Chief, Floodplain Management
<br />Services U.S. Corps of Engineers, Sacramento District regarding the Hydrology and
<br />Hydraulics Determinations for the September 1978 Floodplain Report,
<br />. Peak Streamflow for USGS gaging station number 09166500, Dolores River at
<br />Dolores, Colorado dated 11-02-2001.
<br />. Floodplain Resolution Number 00-525 dated September 25, 2000 for Flood Insurance
<br />Study, Montezuma County, Colorado, dated May 4, 1989.
<br />
<br />Technical Review Findings
<br />The CWCB review is based on an evaluation of available information and a field
<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 was
<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 CWCB and Corps of Engineers originally completed the Flood
<br />Hazard Information Study during 1977 and 1978, The engineering information in the
<br />Corps report was utilized for the official Montezuma County, Colorado Flood Insurance
<br />Study dated May 4, 1989, The lOa-year floodplain in the Corps and FEMA studies is in
<br />fact the designated floodplain for the Dolores River in Montezuma County, Colorado,
<br />The CWCB review focused on the following engineering considerations only:
<br />1, Base topo graphic mapping and field surveys
<br />2, Hydrologic analysis
<br />3, Hydraulic analysis
<br />4. lOa-year floodplain delineation
<br />5, Stream and channel geomorphology
<br />6. Gravel pit operations impact to the designated 100-yr floodplain
<br />
<br />Brief descriptions are provided below for each of the review categories listed above,
<br />
<br />L Base Mapping and Surveys: The CWCB, in cooperation with Montezuma County,
<br />contracted the professional mapping services of Benchmark Mapping Services 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 />
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