The Navajo-Gallup Water Supply Project (NGWSP), upon its completion, will provide a reliable municipal, industrial, and domestic water supply to; Navajo Nation communities located in New Mexico, the City of Gallup located in New Mexico, Window Rock and Fort Defiance Arizona, the Navajo Agricultural Products Industry, and a portion of the Jicarilla Apache Nation. These areas currently rely on a rapidly depleting groundwater supply that is of poor quality and inadequate to meet the current and future needs. The Secretary of the Interior, acting through the Commissioner of Reclamation is authorized to design, construct, operate and maintain NGWSP facilities that include service connections to public water systems. As such, the July 2009 NGWSP Planning Report/Final Environmental Impact Statement (PR/FEIS) described large water tanks near the trunkline with booster stations that were designated as turnouts for the connections to public water systems to provide water to communities to be serviced by the main trunkline. The Construction Cost Estimate (CCE) included the costs for the tanks and booster stations associated with these turnouts, but no connection to existing public water systems. The Navajo Nation Department of Water Resources (NNDWR) has worked with the members of the NGWSP Project Construction Committee (PCC) to develop a prioritized connection plan list. These proposed connection plans are different than the connection concepts in the PR/FEIS in that the connection plans are based on conveying water from the main NGWSP trunkline to the supply points of the closest Navajo Tribal Utility Authority (NTUA) public water systems. While the connections to existing and future water distribution systems have been termed the lifeblood of the NGWSP, as the designs and estimates for NGWSP features continue to be refined and updated, it is uncertain whether room exists within the CCE to design and construct all of these connection plans. Given the importance of the connection plans coupled with the uncertainties surrounding NGWSP funding of these plans, the Navajo Nation and Reclamation have determined that it is in the best interest of the NGWSP to complete Preliminary Engineering Reports (PERs), as described in United States Department of Agriculture (USDA) Rural Utilities Service (RUS) Bulletin 1780-2, on the highest priority connection plans. A PER is a planning document required by many state and federal agencies as part of the process of obtaining financial assistance for development of drinking water, wastewater, solid waste, and stormwater projects. An applicant for funding from the Waste and Water Disposal (WWD) program must submit a PER as required by 7 CFR 1780.33(c) and 1780.55. The PER describes the proposed project from an engineering perspective, analyzes alternatives to the proposal, defines project costs, and provides information critical to the underwriting process. The connection plans were priority ranked and selected based on the number of water haulers, the percent of water haulers in the communities, the shortage of groundwater, the cost per acre-foot of water delivered, and construction sequencing. The PERs would result in much more reliable estimates of the total connection costs, and would be used to leverage funds from other programs for design and construction.