WSP05071

• File Number: 8146.400
• Description: Pueblo Dam - Reports
• State: CO
• Basin: Arkansas
• Water Division: 2
• Date: 10/1/1994
• Author: US Geological Survey
• Title: Use of Frequency Analysis and the Extended Streamflow Prediction Procedure to Estimate Evacuation Dates for the Joint-Use Pool of Pueblo Reservoir Colorado
• Water Supply Pro - Doc Type: Report/Study

3GC2

Tabla 3. Ten largest April-May discharge volumes for Fountain Creek and the
Sf. Charies River

April-May
discharge volume
(.c....r..l)

R.nk of Aprll-M.y
discharge volume

Water year

Number or day. rankacl
&qua/to or hlgh.r th.n
I'8nk of discharge YOlume1

75,200
70,000
53,700
50,700
43,600

STATION 07106500 fOUNTAIN CREEK AT PUEBLO
] 1942 21
2 1980 19
3 1985 30
4 1973 16
5 1957 21

39,600 6 1983 41
38,900 7 1947 21
30,700 8 1944 32
30,400 9 1984 46
29,300 10 ]987 5]
ST. CHARLES RIVER-STATIONS 07108500. 071(18800, 07108900, AND 071_
87,700 1 ]942 46
44.100 2 1987 23
34,800 3 1980 20
25,400 4 1983 25
23,400 5 1944 21

l

21.800 6 1947 21
19,700 7 1984 37
18.400 8 1924 40
17,900 9 194] 24
13,400 10 1985 31

IThis column indicates the Dumber of days in which rank or recorded daily mean discharge during April
and May of indicated year was equal to cr higher than rank. of April-May discharge '\lolwne.

Adjustment and Extension of Discharge
Record

Discharge in the Arkansas River is affected to
varying degrees by diversion and reservoir regulation.
Generally, the effects are not substantial upstream from
Pueblo I{eservoir during April and May; also, the
effects decrease as discharge in the river increases.
However, three diversions (the Bessemer Ditch, the
West Pueblo Ditch, and the Pueblo Water Works
intake), which are downstream from Pueblo Reservoir,
have a direct effect on discharge at the near-Pueblo sta-
tion; hence, recorded discharge at the station is some-
what less than the reservoir inflow.

The Bessemer Ditch has the largest effect on dis-
charge at the near-Pueblo station; the ditch has a decree

to divert as much as 392 ft3/s. The West Pueblo Ditch
has a decree to divert as much as 18 ft3/s and the Pueblo
Water Works has a decree to divert as much as 83 ft3/s
(Abbott, 1985, p. 60-63). Daily records of the quantity
of discharge diverted at the three diversion structures
were compiled for the PR1UP study in conjunction
with applying the operational capability of the
NWSRFS model, but only for water years 1949-87.
The records that were compiled indicate that the diver-
sions usually do not operate at maximum capacity dur-
ing April and May and that the quantities that are
diverted during this time generally are smallest during
early April and largesl during late May.
To adjust the record for the near-Pueblo station
for the effects of diversion, the 75th percentile of the
daily mean discharge diverted by the three structures

FREQUENCY ANALYSIS OF HISTORICAL DAILY MEAN DISCHARGES 21