Currently, the residents of the San Ildefonso, Cuyamungue, Pojoaque, Nambé, and Tesuque Pueblos, and various Santa Fe County (county) customers in New Mexico are served by multiple distinct water distribution systems, each with its own local water supply wells and water storage tanks. Over recent years, it has become evident that a regional integrated system is needed to provide safe and reliable water for the region's future needs, including fire flow and emergency storage. To support the region, the U.S. Department of Interior, Bureau of Reclamation (USBR) is partnering with the pueblos and county to provide additional treated water to the region through the Pojoaque Basin Regional Water System (PBRWS). The PBRWS includes a new source water intake at the Rio Grande River, a new 6 million gallons per day (mgd) water treatment plant (WTP), several new storage tanks, and an integrated transmission system that interconnects the various distribution systems that currently supply drinking water to the region. The new system is expected to simplify maintenance, standardize the level of service, and provide higher quality water to the communities. The extensive scope of the project—spanning over twenty miles along the Pojoaque River Basin—presented unique challenges in the configuration and layout of the integrated transmission and distribution system. Primary among these challenges were the potential for high water ages in parts of the system and the potential for complicated operations between the various interconnected systems. These challenges were made more acute because the system is being designed for a future capacity much higher than the demands expected when the system is first placed into service. To address these challenges, the design team performed extensive steady-state, extended-period, water-age, and transient hydraulic modeling on the system. This paper shows how this modeling identified an optimized system configuration that significantly reduced operational complexity, reduced water-age, and will provide a reliable and safe water supply for PBRWS customers.