Broad-Scale Groundwater Recharge

The Cottonwood Ranch is approximately 2,650 contiguous acres on the south bank of the Platte River between Elm Creek and Overton, Nebraska. The Platte River Recovery Implementation Program prioritized the location for implementation of a broad-scale groundwater recharge project. HDR worked with the Program to identify and understand the key design elements and constraints for a project that would optimize recharge and provide better roosting habitat for federally endangered whooping cranes, as well as gain the ability to re-time water to the river.

The Program incorporated a pioneering approach to better manage target flow deficits in the Platte River for the health of the ecosystem and the people who depend on it. 

We designed and constructed eight water retention cells over roughly 400 grassland acres, created by approximately 6.5 miles of earthen berms no higher than 6 feet tall. When the Platte River flows exceed target levels, excess flows are diverted from a canal to the Cottonwood Ranch via a new 42-inch conveyance pipeline. Water is impounded in the retention cells at depths of 12 inches or less, creating suitable habitat for the endangered whooping crane. At the same time, water slowly recharges the groundwater and is ultimately returned to the Platte River to increase the river’s flow when flows are below target levels to reduce the shortage. 

The project included innovative techniques and modeling and a state-of-the-art flow control system to overcome flat topography, berm under-seepage concerns, and borrow site grading challenges.

Our team provided timely reviews and responses to produce submittals and requests for information to keep the project moving forward and meet the aggressive design schedule set by the Program. On-site coordination between the resident project representative, design staff and the contractor’s superintendent allowed for the anticipation of potential construction issues and the avoidance of them. The team also overcame wet (flooding) conditions during the construction window.

In addition to using recharge to re-time water so flows are available during times of shortage, the project meets the goals and objectives of the program to manage land and water resources to provide benefits for four “target species” on the Platte River in Nebraska: the endangered whooping crane, interior least tern and pallid sturgeon, and the threatened piping plover.