PUB00118

• Year: 2000
• Title: Arkansas River Water Needs Assessment
• CWCB Section: Interstate & Federal
• Author: Smith and Hill
• Description: Information and findings associated with the Arkansas River Water Needs Assessment study
• Publications - Doc Type: Historical

Arkansas River Water Needs Assessment - Section 1. Executive Summary

flow management program was started in 1990.
This program sets target flow ranges for 12 months
of the year, and it involved augmentation of late July
and early August flows is some water years.

Flow augmentation appears to continue flow levels
that have been present since a significant change
that occurred in rhe early 1900's. Even though the
flow augmentation program was operated during
the 1990-95 period, there were many days in the
August 1-15 period in which flows were less than
700 cfs because other factors were at work on the
river that reduced flows. The percent of days in
which flows exceeded 700 cfs during the August 1
to August 15 period is as follows:

~ Prior to 1900
~ 1911-1960
~ 1982-1989
~ 1990-199

40 percent
75 percent
80 percent
77 percent

In contrast to late summer, the effects of institu-
tional management since 1982 are clearly evident
during the November-April period. Since 1982,
an average of 40,000 acre-feet of additional water
is passed during this period. Mean daily flows
have increased approximately 100 cfs during the
winter months, in comparison to the 1911-1960
period. This movement can be accounted for by
the new movement of water from the upper reser-
voirs to lower basin storage to allow for spring
runoff storage in the upper basin.

Operation of the Fryingpan-
Arkansas Project

Water Management Objectives and
Actions to Optimize Yield

The purpose of presenting a baseline hydrograph for
the Arkansas River is to compare the water needed to
support natural resource values with flows designed
to optimize water available for consumptive uses.

The baseline Arkansas River hydrograph presented in
this secrion represents Arkansas River flows from
1982 to 1994, incorporating Ftyingpan-Arkansas
operations during that time period. When utilizing
the baseline hydrographs in this section, the
following limitations should be kept in mind:

- The Ftyingpan-Arkansas Project regulates only a
fraction of total flows in the upper Arkansas
River basin, and other legal/institutional facrors
playa large role in determining flow rates.
However, the Ftyingpan-Arkansas Project is
among the largest of many factors in deter-
mining flow rates experienced in the Arkansas
River corridor.

This baseline does not mimic all of the historic
operations of the Project, because significant
changes in flows have been implemented as
various components of the project have come
online, and as BOR has gained more experience
in opetating the Project.

The 1982-1994 period may not be representa-
tive of the entire range of hydrologic conditions
that could be experienced in the future.

This baseline represents an operation that is in
variance from the CDNR flow recommenda-
tions that have been implemented since 1990.

The baseline developed in this section is a represen-
tation of what flows would be expected to occur in
the tiver corridor if the Fryingpan-Arkansas Project
were to be operated today to best achieve the
following goals:

Maximize storage of Project water
Minimize unnecessaty spilling of non-Project
water
Minimize loss of Project water to evaporation
Maximize energy generation at the Mt. Elbert
Power Plant

Full implementation of these goals would entail the
following Project operations:

- Water would be evacuated from Turquoise Lake
and Twin Lakes and stored in Pueblo Reservoir,

1-8 - Operation of the Fryingpan-Arkansas Project