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<br />Historically, the Grand Valley was dominated by desert vegetation
<br />communities, with narrow wetland and riparian zones along the Colorado
<br />~ and Gunnison Rivers and some of the larger natural washes. The present
<br />~8 mosaic of cover types (agricultural, riparian, marsh, and desert shrub)
<br />~ is a direct result of the current irrigation systems. With the advent
<br />CJ of irrigation (waste water, return flow and seepage), the natural
<br />vegetation changed from sparse, saltbush desert communities to crops or
<br />cover types such as marsh/riparian, cottonwood, tamarisk, saltbush and
<br />greasewood. These cover types are restricted to areas unsuitable for
<br />agriculture, such as canal and lateral banks, fence rows, washes,
<br />irrigation return drains, roadsides, and other low lying areas.
<br />
<br />The agricultural vegetation type is composed of orchards, pastures, and
<br />such crops as alfalfa, corn, and small grains, which are entirely
<br />dependent upon irrigation for their existence.
<br />
<br />The agricultural habitat type is the most extensive type in the valley
<br />and is comprised of farmyards, fields, ditches, and patches of weeds.
<br />Roadsides, field edges, and canal banks within the agricultural area
<br />provide good distribution of wildlife cover. The agricultural habitat
<br />is also important as a feeding area.
<br />
<br />The cottontail rabbit uses this type, finding food and cover along
<br />ditches and weed patches, with agricultural crops providing additional
<br />feeding areas. The striped skunk, muskrat, gray fox, and raccoon
<br />utilize the farm land and associated ditchbanks. Small mammals such as
<br />the deer mouse, harvest mouse, long-tailed vole, rock squirrel, and
<br />prairie dog are locally abundant. The ring-necked pheasant, Gambel's
<br />quail~ and mourning dove use the habitat for feeding, nesting, and
<br />protective cover. Waterfowl and shorebirds utilize this type for
<br />feeding, particularly during winter months when large flocks of mallard
<br />ducks and Canada geese depend on croplands for feed. Raptors hunt
<br />agricultural habitat and non-game birds forage in this habitat
<br />seasonally.
<br />
<br />Methodology
<br />
<br />In the 1988 M&E Report, monitoring consisted of recording acres of
<br />wetland and upland changes on 77 operating units before construction,
<br />after construction and three years after construction of salinity
<br />practices. The 77 operating units represented 102 referrals under the
<br />Agricultural Conservation Program (ACP) program. Wildlife habitat
<br />changes recorded on the 77 monitoring units were extrapolated to
<br />represent the estimated 4185 referrals.
<br />
<br />The Grand Valley wildlife habitat program replaces lost habitat using
<br />the "acre for acre method". 'For example, when a hedgerow 2178 feet long
<br />is planted, with an average width of 20 feet, it applies one acre of
<br />upland habitat towards the reduction of USDA replacement acres.
<br />
<br />The Grand Valley Environmental Assessment was prepared jointly by Bureau
<br />of Reclamation (BOR), USDA, and the US Fish and Wildlife Service
<br />(USFWS). The Environmental Assessment required the replacement of 4,000
<br />acres of wildlife habitat due to potential construction activities. The
<br />analysis indicates 70 percent would be assignable to the BOR Water
<br />Quality Improvement portion of the project and 30 percent (1200 acres)
<br />would be assignable to the USDA On-Farm Development.
<br />
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