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<br />in sedimentat ion is expected. Due to the sandy nature of the so; 1, and the measures to be
<br />taken to stabilize the area of impact, no long-term effects are foreseen with regard to
<br />turbidity. No significant change of dissolved minerals in the water is anticipated. The water
<br />temperature is expected to be more uniform throughout the year than under present conditions;
<br />however, it is expected that temperatures will rise to historic levels, the further water
<br />travels downstream of the dam.
<br />
<br />8. Fish. According to the Fish and Wildlife Service, the existing sport fishing in the
<br />SoutlllTfatte River at the Narrows site is negligible. The major impact on the fishery resource
<br />would be the conversion of the lotic (riverine) environment into a lacustrine (lake) environ-
<br />ment. With the development of a fish hatchery, the reservoir is expected to provide a high
<br />quality warm-water fishery consisting of such species as walleye (Stizostedion vitreum)
<br />northern pike (Esox lucius), largemout.h and smallmouth bass (Micropterus salmoides and
<br />,t!. dolomieu), channel camsn (Ictalurus spp.), crappie (Pomoxis spp.), and bl uegi II (Lepomis
<br />macrochlrus). After reservoir construction, water conditlOns may be favorable for the estab-
<br />lishment of a cold-water fishe~y immediately downstream pf the damsite.
<br />
<br />9. Benthos. It is anticipated that a Significant change in species composition of the benthic
<br />community would take place with impoundment. Presently, there is a limited benthic community
<br />due to the shifting sandy bottom. The benthic community is dominated by tubificids and midge
<br />larvae. These specific organisms are known to thrive in productive reservoirs and it is fully
<br />expected they would, flourish with the implementation of the Narrows Unit.
<br />
<br />10. Riparian Woodlands. Dam construction on the river would cause the inundation of
<br />2,666 acres (1,079 ha) of riparian bottom lands comprised of 1,621 acres (656 ha) of open
<br />cottonwood stands, 62 acres (25 ha) of closed cottonwood stands, 749 acres (303 ha) of mixed
<br />willow-cottonwood stands. 64 acres (26 ha) of pure willow stands, and 170 acres (69 ha)
<br />of open park.
<br />
<br />11. Wetlands. A total of2,500 acres (1,012 ha) of wetlands within the conservation pool area
<br />would be lost upon filling; however, it is expected that increased irrigation water would cause
<br />increased seep areas and ponding in low-lying areas which would su_pport wetland invader spe-
<br />cies. The intensive wildlife management plan would impound 540 acres (219 ha) of open-water
<br />marsh. Additionally, a 13,18g-acre (5.340-ha) reservoir would be created.
<br />
<br />12. Wildlife Habitat. The loss of 13,189 acres (5,340 ha) of potential or usable wildlife
<br />habitat within the conservation pool would take place. This wildlife habitat consists of
<br />irrigated cropland, sand sage, riparian woodlands (willow and willow-cottonwood) and wet meadow
<br />complexes.
<br />
<br />13. Federall Listed Endan ered and Threatened S eci.es, As stated in the Narrows Unit
<br />8iolo lea ln10n - a a e, ere nne- a con an Black-footed Ferret (December 2, f98!)
<br />the propose Narrows mt 15 not lke y to Jeopar ize the cant nue ex st~nce of the peregrine
<br />falcon (Falco peregrinus) and black-footed ferret (Mustela nigri~es). The continued existence
<br />of winterTng oald eagles (Haliaeetus leucocephalus) 1S not llkely to be jeopardized with
<br />certain conservat ion stipul at ions (preservat 10n of mature roost and perch trees and follOW-Up
<br />eagle studies) provided in the current wintering areas along the South Platte River (See
<br />Biological Opinion, appendix C). The conservation measures will be implemented except where
<br />structural development would require removal of mature cottonwoods.
<br />
<br />A jeopardy biological opinion on the whooping crane (Grus americana) in central Nebraska was
<br />issued on January 20, 1983. by the Fish and Wildli1eService Regional Office in Denver,
<br />Colorado. The FWS had determined that the channel width in the critical habitat reach and the
<br />avai lable roosting habitat would be adversely modified by reduced flows resulting from the
<br />Narrows Unit. This opinion presented an alternative to prevent the project's effects and
<br />stated that " , . roosting habitat can be maintained at 1,100 ft3 during the periods
<br />February 1 to May 10 and September 16 to November 15 . , . ,II Additionally, IlA stream power
<br />regime of 3,800 ft3 for 23 days to maintain ri ver channel width . . ." was del ineated. In
<br />March 1983, an interagency task group composed of staff from the Bureau and Fish and Wildlife
<br />Service was formed to identify additional water and/or land management alternatives to remove
<br />the jeopardy finding rendered by the Fish and Wildlife Service, This group identified a number
<br />of alternatives which- it bel ieved could provide the suitable habitat characteristics conducive
<br />to continued whooping crane use in the area of concern, However, it was concluded that ~one of
<br />the alternatives, including the plan recommended in the biological opinion issued on January
<br />20, 1983, are completely satisfactory due to the lack of: certainty that, if implemented,' the
<br />desired results of providing for whooping crane habitat would be achieved. As a result, the
<br />Regional Directors of the two Interior agencies have agreed to a plan of action to field test
<br />a number. of these measures over the next 2 years with the goal of developing an acceptable
<br />and implementab!e plan for whooping crane habitat management that would remove the jeopardy
<br />opinion. The plan of action is contained in AppendiX D.
<br />
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