WSP07251

• File Number: 8143.600.10.A
• Description: John Martin Reservoir - Operation Studies
• State: CO
• Basin: Arkansas
• Water Division: 2
• Date: 12/1/1981
• Author: Zorich/Spronk Assoc
• Title: Analysis of John Martin Reservoir Operation
• Water Supply Pro - Doc Type: Report/Study

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ZORICH, SPRONI< a ASSOCIATES, INC,

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also provides an indication of any changes in the amounts

of diverted river flow affected by adoption of the Compact.,

Table 2 contains the 1913 to 1975 annual and accumulated Ar-

kansas River discharges as recorded at the United States Geo-

logical Survey gaging stations located near Pueblo and at La

Junta. Most of the diversions of the District 14 and 17 ditches

are made from the river between these two gaging stations.

Analysis of the summary contained at the bottom of Table

2 indicates that the average annual Arkansas River discharge

has been decreased substantially more at La Junta than near

Pueblo during the post-Compact time period. If the ratio be-

tween the discharge at the two gaging stations as determined

for the pre-Compact period had remained unchanged during the

1950 to 1975 time period, the 1950 to 1975 average discharge

at La Junta would have been 185,772 acre-feet per year. Thus,

the river flows at La Junta (relative to those near Pueblo)

have been reduced by an average of 64,810 acre-feet per year

(185,772 - 120,962) during the period of time since the Compact

was adopted.

Figure 4 is a graphical presentation of the data contained

in Table 2. The slopes of the two line segments indicate that

the annual La Junta discharge has averaged only 27 percent of

the annual Pueblo discharge during the post-Compact period, as

compared to 40 percent during the pre-Compact period.

The changes in the relationship between river flow into

and out of Districts 14 and 17 may not be solely due to increased