WSP01670

• File Number: 8143.600.10
• Description: John Martin Reservoir - Operation Studies
• State: CO
• Basin: Arkansas
• Water Division: 2
• Date: 3/1/1954
• Title: Historic Inflows to John Martin Reservoir in Excess of 2000 cfs 1931-1953
• Water Supply Pro - Doc Type: Report/Study

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M E M 0 RAN DUM

March 1954

To: Ivan C. Crawford

From: R. I,l. Gildersleeve

Subject: Historic Inflows to John Martin Reservoir in Excess of 2,000 c.f.s.

Pursuant to your request, the engineering staff has summarized data
with respect to historic inflows to John V~rtin Reservoir of more than 2,000
c.f.s. for the period 1931 - 1953. The attached tabulation sh~vs the distri-
bution of such inflows throughout the period. In the 22 years of the period,
exclusive of the year 1942, there were 59 instances in which mean daily inflows
to the reservoir were in excess of 2,000 c.f.s., the duration of such instances
ranging between 1 day and 16 days. In 50 cases the mean daily flow on the first
day was between 2,000 c.f.s. and 5,000 c.f.s.; in 5 cases, between 5,000 c.f.s.
and 10,000 c.f.s.; and on 4 different occasions the inflry,1 on the initial day
was more than 10,000 c.Ls. During the year 1942, there was a period of about
45 consecutive days on which mean daily inflow was above 2,000 c.f.s., beginn-
ing with April 19.

For the purpose of analyzing the possible effects of the flood in-
fl~ls under conditions of priority administration on the river, the period was
divided into two groups of II years each, prior and subsequent to the operation
of the reservoir.

For the years 1931 - 1941, records are available of daily flows at
either La Junta or Las Animas, and on the Purgatoire, at Lamar, Holly and
Garden City. Records of the diversions of the "Garden City" group of ditches
have also been published.

i(ecords of daily stream flows at the same points are also available
for the 1943 - 1953 period, and also either actual diversions or demands for
the same group of ditches. However, during this period there was water stored
in the reservoir most of the time, and it is a matter of judgment as to what
the flows at Holly and Garden City might have been under a different pattern
of releases from the reservoir.

As a further breakdown in the analysis, the inflows were divided in-
to three groups: those of mean daily amounts between 2,000 ahd 5,000 c.f.s.,
those between 5,000 and 10,000 c.f.s., and those above 10,000 c.f.s. The number
of days of duration of inflows above 2,000 c.f.s. was also noted, '"ith the flow
on the initial day determining the group placement of a flood flow. The fl80ds
were also segregated roughly into four classifications:

(a) Mean daily flow at Holly of not more than 1,000 c.Ls. for
one or two days, vdth no significant flow past Garden City.

(b) Mean daily flow at Holly in excess of 1,000 c.f.s. for
one or two :lays, with no signific ant flow past Garden City.