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<br />The river outlet works will have a capacity to
<br />release up to 5,000 fta/s to provide normal river
<br />releases. A separate outlet works will release water
<br />into the Fort Morgan Canal.
<br />
<br />Feature Current Plan 1976 Plan
<br />Dam and reservoir (feet)
<br />~aximum water surface 4,433.3 4,448,5
<br />Crest elevation 4,440 4,454
<br />Height, dam 133 147
<br />length, dam 18,000 22,400
<br />Crest width, dam 30 30
<br />Slurry trench yes yes
<br />Acres inundated
<br />(top conservation pOOl) 13,189 13,189
<br />Acres inundated
<br />(maximum water surface) 27,628 40,813
<br />Spillway crest length (feet)
<br />Service 50 gated 50 gated
<br />Auxiliary. 1,500 750
<br />Spillway design capacity (ft'/s)
<br />Service 42,500 78,660
<br />Auxiliary 350,000 155,830
<br />
<br />Narrows Reservoir
<br />
<br />Flood control pool has been reduced from 475,000
<br />to 233,000 acre-feet, and the 75,000 acre-foot joint-
<br />use pool has also been eliminated.
<br />
<br />The flood control space will regulate a flood
<br />estimated to have a recurrence interval of once
<br />every 25 years instead of 100 years as was
<br />proposed in the 1976 plan.
<br />
<br />Although the single purpose flood control pool has,'
<br />been reduced, the dam and spillways have been
<br />designed to accommodate the maximum probable
<br />flood.
<br />
<br />These reductions mean that gross storage is
<br />reduced by 509,000 acre-feet. Surcharge storage
<br />has also been reduced from 636,000 to 444,000 acre-
<br />feet.
<br />
<br />Initial reservoir
<br />storage capacity Current Plan 1976 Plan
<br />(acre-feet)
<br />Dead storage 0 0
<br />Inactive 50,000 50,000
<br />Conservation 373,000 373,000
<br />Joint use 0 75,000
<br />Flood control 233,000 475,000
<br />Surcharge 444,000 636,000
<br />Total 1,100,000 1,609,000
<br />
<br />Functions
<br />
<br />Narrows Unit purposes include irrigation, M&I
<br />water supplies, flood control, recreation, and fish
<br />and wildlife enhancement. Comparison of pur-
<br />poses between the 1976 and current plans is as
<br />follows:
<br />
<br />Function Current Plan 1976 Plan
<br />Irrigation (acres) 287,070 287,070
<br />Period of record 1941-1977 1947-1974
<br />(acre-feet) 108,350 133,000
<br />M&I (acre-feet) 21,850 deferred
<br />Inflow design flood
<br />Volume (acre-feet) 2,230,000 2,230,000
<br />Peak (ft'/s) 497,000 497,000
<br />Storage
<br />Flood control 25-year 100-year
<br />(acre-feet) 233,000 475,000
<br />Joint-use
<br />(acre-feet) none 75,000
<br />Recreation
<br />Visits
<br />Initial( 1,190,000 1,225,000
<br />ultimate 1,190,000 1,592,500
<br />Acres j; 1,340 970
<br />Fish and Wildlife
<br />Enhancement
<br />Fish hatChery yes yes
<br />Jackson lake No Federal action yes
<br />Specific fish and
<br />wildlife lands
<br />(acres) j; 6,758 7,170
<br />
<br />Benefits '
<br />
<br />Irrigation..,-about 99,500 acre-feet of water will be
<br />available from Narrows Reservoir for agricultural
<br />and M&I uses. This figure has decreased from
<br />102,000 acre-feet shown in 1976 for irrigation only. '
<br />
<br />In addition, 23,900 acre-feet of use able return flows
<br />are expected to be available.
<br />
<br />Irrigation water will be used on farmland within
<br />the Central Colorado and Lower South Platte
<br />Water Conservancy Districts. These land's are
<br />located in Adams, Weld, Morgan, Logan,
<br />Sedgwick, and Washington Counties.
<br />
<br />The Lower South Platte and Central Water
<br />Conservancy Districts will contract with local
<br />entities and individuals for water sales. Requests
<br />indicate demand for Narrows water is greater than
<br />the potential supply.
<br />
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