9528 ‎(2)‎

• UCREFRP Catalog Number: 9528
• Author: Martinez, P. and N. P. Nibbelink.
• Title: Colorado Nonnative Fish Stocking Regulation Evaluation.
• USFW Year: 2004.
• USFW - Doc Type: Grand Junction, Laramie.
• Copyright Material: NO

Pond, Lake and Reservoir Locations, and Hvdrog~ranhy
The goal of this section was to determine the number and distribution of pond, lake, and
reservoir resources below 6,500 feet in elevation surrounding the critical habitat reaches of the
Gunnison and Colorado rivers. Also, there was a need to produce GIS-based maps of ponds,
floodplains, lakes and reservoirs in the Colorado and Gunnison River basins below 6,500 feet in
elevation, and an associated descriptive list. To illustrate the distribution of standing water
resources in western Colorado, aGIS-based map was also produced for the state west of the
Continental Divide. The pond data for the ISA were digitized and attributed from the four
primary sources listed below. The accuracy and utility of these data is dependent upon the
quality, completeness, and dates of these sources.
1) The hydrography created and maintained by the CDOW's Aquatic GIS Coordinator in Fort
Collins, CO (Colorado Division of Wildlife, 15 February 2000, co_lakes3).
2) The pond maps provided by Anita Martinez, CDOW Nonnative Fish Control Biologist, for the
Colorado River from river mile 150 to 186.
3) Aerial photography from 1997 provided by Mesa County.
4) Aerial photography from 2000 provided by the USFWS.
The map creation and analysis of pond, floodplain, lake and reservoir resources took
place at two scales. The lakes and reservoirs were viewed, and associated fish stocking and/or
composition data analyzed, for all of Colorado west of the Continental Divide. This GIS data
layer came from the A~GIS_DOW-CD; specifically the "co_lakes3" layer that was used for this
work. The pond resources layer, including analyses of associated fish populations, if known,
were created, viewed and analyzed at a much finer resolution for only the primary study area.
This included river miles 152-185 on the Colorado River and when data allowed, through river
mile 240 on the Colorado River and river miles 0 to 52 on the Gunnison River (Figure 1).
Aerial photography obtained from Mesa County had been orthorectified, so no
transformations were necessary in order to digitize ponds. The photography from the USFWS
was rectified by the contractor using both Digital Raster Graphics (DRGs) and Digital
Orthophoto Quarter Quads (DOQQs), as available. The rectified photography from the USFWS
should not be used for accurate spatial positioning of other features. Features were rectified to
maximize the accuracy of the spatial position of standing water resources visible in the photo.
Pond outlines were digitized for the Colorado River and Gunnison River within the ISA.
The ponds were attributed interactively with "Mitchell codes" (Mitchell 1995), with the aid of
the pond maps, described above, compiled by Anita Martinez, CDOW. This allowed us to link
the geographic features of ponds having codes to data on pond attributes, including information
on control structures and fish species composition available from Anita Martinez. The final
version of the primary study area pond dataset is an ArcView shapefile (spatial data layer) called
"ISAPonds" and it includes all attributes available from the floodplain pond database of
Martinez (2004).
The 50- and 100-year floodplain data for the primary study area (Colorado and Gunnison
rivers) were scanned and digitized from a series of reports produced by the Colorado Water
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