Report on Estimated Cost for Expansion Tamarack Managed Groundwater recharge Project

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4. The United States Fish and Wildlife Service has identified three species of birds (Whooping Crane, Least Tern, and Piping Plover) and one specie of fish (Pallid Sturgeon) within the Platte River Basin as either threatened or endangered under the Endangered Species Act. This project will contribute to the Tamarack Plan and thereby incidentally benefit these species by reducing shortages to target flows in the "associated habitats." 5. This augmentation may also protect existing water supplies which are used for various purposes including agricultural, municipal, domestic, and wildlife management within the South Platte Basin in Colorado by crediting augmentation water to replacement for depletion. The project consists of batteries of wells situated along the banks of the South Platte River operated in conjunction with a series of recharge ponds occupying shallow natural depressions, still within the Platte River valley, but at greater distances from the river. The wells withdraw water from the alluvial materials underlying the Platte River at times when river flows are in excess of the legal and physical demands for water. The water is pumped via buried pipelines to the recharge ponds where it infiltrates and eventually returns to the river. The timing of return flows to the river can be predicted based upon the aquifer characteristics and the distance between the recharge ponds and the river. Accordingly, the project can be used to re- regulate the timing of flows in the South Platte River. The project can be configured in such a way as to cause return flows to the river during low flow periods, thereby benefiting wildlife habitats. The project can also be configured so as to "...protect existing water supplies ... by crediting augmentation water to replacement for depletion" (Final Environmental Assessment, 1999). The full scope of the project was described in the Final Environmental Assessment. The initial phases of the project were constructed beginning in 1996, and have been in operation since that time. The purpose of this report is to identify the work required to complete the project, and to estimate, at a concept level, costs associated with construction of the remaining elements of the project. Plate 1 (in pocket) shows the facilities constructed to date and those required to complete the project as described in the Final Environmental Assessment. Facilities needed to complete the project include the following main elements: • 21 wells (TRSWA) • Infiltration gallery (PESWA) • Surface facilities at the 21 wells and the infiltration gallery • A pumping lift station • Power service to the 22 pumping sites and lift station • Pipelines to deliver water to 11 recharge pond complexes • A jack and bore beneath Interstate 76 for a 24 -inch water delivery pipeline - 2 _ %305�LE