WSP08574

• File Number: 8141.100
• Description: Fryingpan-Arkansas Project - Project Description
• State: CO
• Basin: Arkansas
• Date: 1/1/1969
• Author: US DoI BoR
• Title: Flood Control Fryingpan-Arkansas Project Eastern Slope Features
• Water Supply Pro - Doc Type: Project Overview

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22. Evaporation records for the basin:are rather sparse and in-
complete with only two stations. Pueblo City Reservoir has an average
total pan evaporation for the period May through October of 57.72 inches.
Sugarloaf Reservoir has an average total pan evaporation for the period
July through September of 15.11 inches.

23. STREAMFLOW CHARACTERISTICS.- The:Arkansas River is a steep
mountain stream from its source to Canon Ci~y, a distance of 128 miles.
Near Canon City, the river emerges from the'mountains through the:Royal
. Gorge. Stream gradients often exceed 50 fe~t per mile above Canon City
and decrease to 10 feet per mile at Pueblo.

24. The Arkansas River floods are of two general types. "Spring
, ,floods" which' result from snowmelt, 'often' allgmented by storm runoff, and
"summer floods" which result entirely from ~torm runoff. The spring
floods are characterized by moderate flows pf long duration,engendering
a large volume of runoff. The summer floods are characterized by high
discharges and relatively small volumes of runoff.

25. The mountainous areas above Canon City are not conducive to
high peak floodflows. Streamflow records at Canon City show that for
75 years of record the highest peak discharge from a drainage area of
over 3,100 square miles is 19,000 c.f.s., which occurred on 2 August
1921. Most of this flow originated from Gr~pe Creek, a right bank trib-
utary immediately upstream of Canon City. The second highest peak of
12,300 c.f.s. occurred on 18 August 1909. At Pueblo, with a drainage
area of 4,686 square miles, the peak dischatge for 70 years of record
is 103,000 c.f.s. which occurred on 3 June '1921. The record further
shows that there was a peak discharge of 30,000 c.f.s. on 5 August 1902,
25,600 c.f.s. on 12 July 1923, and 18 other discharges over 10,000
- c.f.s..

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26. The channel capacity of the Arkansas River above John Martin
Dam varies from a few cubic feet per second in the headwaters to a
maximum of about 10,000 c.f.s. in the vici~ities of Canon City and La
Junta. Channel capacities increase from Pueblo to La Junta, and de-
crease from La Junta to Las Animas. The capacities determined by
backwater studies are: below Pueblo, 5,OOQ c.f.s.; at Avondale, 6,600
c.f.s.j at Nepesta, 8,200 c.f.s.j at La Junta, 10,200 c.f.s.; and at
Las Animas, 6,500 c.f.s. Stream gaging dat~ for selected gages in the
Arkansas River Basin in Colorado are listed in table 2. Locations of
stream gaging stations are shown on' plate 2.

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