WSP10371

• File Number: 8111.805
• Description: Arkansas River Compact Administration - Keesee Ditch
• Basin: Arkansas
• Date: 1/1/1986
• Author: HRS Engineering
• Title: Keesee Ditch Change of Water Rights Vol 1 - Historical Operation of Kessee Ditch
• Water Supply Pro - Doc Type: Publication

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mSTORICAL STREAM DEPLETION

The purpose of this engineering analysis is to determine the historical depletions
to the Arkansas River resulting from the operation of the Keesee Ditch. These
historical depletions are the net effect of diversions, consumptive use and irrigation
return flows. The results of the analysis will provide a historical pattern for these
components which can be matched by a similar pattern of storage, exchange and
releases from John Martin Reservoir.

A 20-year study period from 1964 through 1983 was selected for the analysis.
This study period incorporates the recent pattern of irrigation use by the Keesee
Ditch, including a stable pattern of irrigated acreage and crop types, the effects
of John Martin Reservoir operation and the development of ground water resources
along the Arkansas River. A 20-year study period was also considered optimum
for the incluSion of most short-term climatic fluctuations based on research of
climatic cycles in Colorado (Doesken, 1986, pers. comm.)

In order to calculate the amount and timing of historical stream depletions,
the analysis was divided into two major components: an analysis of consumptive
use to determine the amount of irrigation water permanently removed from the
stream system or "consumed", and an analysis of irrigation return flows. The
consumptive Use analysis was a monthly water budget which incorporated data
related to irrigated acreage, crop irrigation water requirements, diversions,
irrigation system losses, and soil moisture storage. The irrigation return flow
analysis incorporated characteristics of the alluvial ground water system to route
return flows from delivery system losses and excess irrigation water back to the
river. The amount and timing of return flows were then combined with the records
of diversions to determine the net effect on the river or the "historical stream
depletion". Figure 2 is a simplified illustration of the movement of irrigation
water through the Keesee Ditch system.

Since surface and ground water irrigation supplies were commingled within
the ditch distribution system, no particular irrigated acreage benefited exclusively
from either source. As a means of separating historical depletions attributable
to the ditch water rights from the effects of the Broyles irrigation wells, it was
assumed that the ditch diversions were limited to the irrigation of a total of 1400
acres, as decreed. The remaining irrigated acreage (about 500 acres), and any

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