Lower South Platte River Study

• Contractor Name: Colorado Water Conservation Board
• Loan Projects - Doc Type: Feasibility Study

Lower South Platte River Study
Colorado Water Conservation Board
1 December 2001
Executive Summary
The Colorado Water Conservation Board (CWCB) commissioned a study to identify and
1 evaluate potential water storage and management options in the Lower South Platte River
Basin. The study was conducted at the reconnaissance level under a contract between the
CWCB and GEI Consultants, Inc. (GEI); Brown and Caldwell assisted GEI with certain
elements of the study. The study was undertaken between January and July 2001, following
a detailed scope of work prepared jointly by GEI and the CWCB.
1 The purpose of the reconnaissance study was to identify potential structural and non-
structural water management alternatives along the Lower South Platte River in a study area
1 (Figure ES.1) extending generally from the Harmony Ditch No. 1 headgate near Crook,
Colorado downstream to the Colorado-Nebraska State line. These water management
alternatives would develop available water under a junior decree. Water thus developed
1 would be available for supplying a variety of beneficial uses, including:
• Providing an alternative and/or new source of water to meet the augmentation needs
of junior water users.
1 • Maintaining stream flows to improve habitat for Colorado minnow species of concern
and for other environmental purposes such as waterfowl and riparian habitat.
1 • Improving water rights administration through increased flexibility for storing and
releasing augmentation water.
1 A key element of a new water management project would be its ability to meet the above
objectives, while maintaining current levels of agricultural production in the Lower Basin.
Significant volumes of water are available to be developed in the Lower Basin,based on a
monthly water availability analysis for the 1943-97 period of record. For example, an
1 average of 192,000 acre-feet per year is available at the Harmony Ditch No. 1 Headgate.
There is extreme variability in the water supply; in a very wet year up to 708,000 acre-feet
may be available in a single month. During low-flow periods, there may be many
1 consecutive months when no additional water would be available under a junior decree.
Providing a dependable monthly water supply to meet the above-noted objectives will require
storage, as indicated below:
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GEI Consultants, Inc. ES-1 01002 Dec 2001 Lower South Platte River Study
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