WSP09175

• File Number: 8443.100
• Description: Narrows Unit - Project Description
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 1/1/1958
• Title: Narrows Unit Colorado
• Water Supply Pro - Doc Type: Project Overview

Morgan Canal. Relocation of the Union Pacific
Railroad, state Highway 144, county roads, and
public utilities would be necessary.

Al.location of the reservoir capacity ;lould
be as follows, excluding surcharge of 818,000 acre-
feet which could provide some flood control bene-
fits:

This project has since been indefinitely deferred
as a potential Reclamation development. The ulti-
mate stage would have enabled the irrigation of
30,000 acres of new land in addition to the supple-
mental service initially provided. N
W
o
o

Function
Flood contro1 . . . . . . . . . .
Joint use (i'lood and irrigation).
Irrigation. . . . . . . . .
Dead storage. . . . . . . . . . .
Total storage capacity

Acre-feet
250,000
15,000
323,000
52,000
100,000

EVENTS SINCE 1951

Recent developments that af'fect the 1951 Plan
for the Narrows Unit are as follows:

The tota.l flood control capacity of 325,000
acre-feet, including joint use space, would be
adequate to control all floods of record on the
South Platte River and Bijou Creek. The exclusive
flood control space would be used. wenever the
irrigation and joint use space is full and the
river inflow exceeds 10,000 second.-feet. The
joint use space would be operated for flood control
and irrigation during the sno_elt period Apr1J 15
to June 15. Sedlinent deposition would reduce the
irrigation and dead storage capacities by an esti-
mated 15,000 acre-feet in 50 years.

1. Present and prospective importations
into the South Platte River Basin have changed
considerably from those anticipated in 1951,
especially for municipal Pur:9oses. The City
of Denver is expanding its facilities for
diverting wa~er from the Fraser and WiLliams
Rivers. Denver is also cOl1structing a system
to import water from the Blue River. The
Cities of Englewood and Aurora have plans for
supplementing their water supplies by importa-
tions from the ColoI""do River Basin. Additional
filings have been made on western slope streams
by the City of Denver and by a private engineer-
ing firm lihich could add to the water supply for
the South Platt.e River Valley.

Two cumulative stages of operation of the
Narrows Unit were planned, based upon water supply
conditions affected by other developments. The
initial stage would have provided supplemental
water for about 230,000 acres of presently irri-
gated land through regulation of flood and surplus
South Platte River flows and retu....n flows from the
Colorado-Big Thompson Project. The next, or ulti-
mate, stage )JaS predicateo. upon return flows that
would develop from the then-planned Blue-South
Platte tranSlllOuntain diversion project.

2. A rapid expansion of well irrigation
has taken place since the water supply studies
were made. The State of Colorado enacted a
ground-water code in 1951. Historical and
potential well developments would have to be
carefully analyzed in new hydrology studies
for the Narrows Unit.

3. Refinement of the flood control
studies for Narrows Reservoir might result in
some revisions to the design of the dam.

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