WSPC03939

• File Number: 8460.500
• Description: Platte River Basin - Endangered Species Issues - South Platte Recovery Program
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 12/5/1995
• Author: Matthew J Cook
• Title: South Platte Agreement - Groundwater Recharge as Augmentation for Restoring Wetlands Along the Central Platte River Nebraska - Final Report
• Water Supply Pro - Doc Type: Report/Study

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000057

1.0 EXECUTIVE SUMMARY

The Platte River in Central Nebraska serves many functions. A portion of
the Platte River from Lexington to Grand Island, Nebraska provides habitat for
several endangered species, including the Whooping Crane.
The migrating Whooping Crane depends on wet meadow habitat found
along the Platte River. However, the river has undergone significant changes
since pre-settlement times that directly affect the wet meadow habitat.
Approximately 70% of the historic annual flow in the Platte River system has
been diverted upstream for consumptive uses resulting in water deficits for many
native wet meadow sites. The average loss of wet meadow complex in the
central Platte River basin, which is used by the Whooping Crane as a foraging
and breeding site, has been estimated at 72%. Only land aquisition efforts have
been made to restore a portion of the wet meadow habitat that has been
converted to farmland or other uses. These efforts protect the required land, but
do not solve the water deficit problem encountered in the wet meadows.
This project served to provide an engineered solution using groundwater
recharge as augmentation for restoring the wet meadows used by the Whooping
Crane. A rectangular recharge basin was designed at the Rowe Sanctuary wet
meadow site near Minden, Nebraska to allow water to be artificially recharged in
order to raise the groundwater table beneath the wet meadow site to within 1 to
1.5 feet of the ground surface. The shallow water table benefits the invertebrate
food supply needed by the Whooping Crane as well as the wet meadow
vegetation,
The geometry of the basin was similar to a long, narrow canal with a width
of 5 feet and a length of 1000 feet. The basin had a trapezoidal cross-sectional
shape with a depth of 1 foot and a side slope ratio of 1:1 for stability purposes.
Using Colorado ~tate University Eit g,nd Well (CSUPAW) software,
developed in 1984 to model the effects of recharge with a rectangular basin in a
stream-aquifer system, an analysis of the reeharge basin was performed to
investigate the effects on the surrounding wet meadow, The analysis showed
that for a small constant recharge rate of 4 feet per day (0.2314 CFS) over a
recharge period of 20 days, the water table increased 1 foot at a distance of 300
feet from the center of the basin. When added to an initial depth to water of 2.4
feet at the wet meadow location, the resulting depth to groundwater would be
within the recommended 1 to 1.5 feet of the ground surface. The resulting
groundwater mound would dissipate slowly allowing the wet meadow vegetation
to benefit long after after the recharge was completed.
A suggested operating guideline for the basin was included in this report.
The recharge basin operation could be timed to stimulate the development of
invertabrates and other food sources required by the migrating cranes prior to
the spring migration period in early March. A steady supply of water for the 20
day recharge period investigated would come from the adjacent south channel of
the Platte River. A small pump with an intake on the river could easily supply
the 0.2314 CFS recharge requirement. The majority of the recharge water would

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