Louisville Water, founded in 1854, is one of the oldest water utilities in the United States. Supplying reliable and safe drinking water to Metro Louisville and its five surrounding counties, numerous large diameter transmission mains flow from the Crescent Hill Water Treatment Plant near downtown Louisville outwards to the exterior limits of Jefferson County. As the surrounding counties grow, demands on the aging system has increased. Development in these counties has boomed over the last decade as new industries, including the Ford BlueOval lithium-ion battery manufacturing plant, are built along the I-65 corridor and as the bourbon industry continues to grow. Resultingly, the need for greater transmission capacity to wholesale customers south of Louisville continues to increase. Wholesale customer Nelson County Water District purchases their water directly from Louisville Water. Because of major new industrial site development and the associated increase in water usage, a new wholesale agreement was put in place between Louisville Water and Nelson County Water District for Louisville Water to provide more water to the county via the new Highway 245 Transmission Main and Master Meter. Collaborative efforts between the owner, engineer (HDR), Kentucky Transportation Cabinet (KYTC), and other utilities in the area were crucial in determining the new transmission main route in a cost-effective design solution. The route evaluation involved meetings with Bernheim Forest and Arboretum, the largest privately owned research forest in the state of Kentucky, to secure required easements and determine tree impacts. During the evaluation phase the team also met with multiple KYTC offices to determine ultimate limits of imminent road widening projects to avoid future relocations. This presentation will cover elements of the Highway 245 Transmission Main design including: method of joint restraint and thrust blocking; hydraulic grade line analysis; design of appurtenances that allow for future condition assessment and for operating the pipe over time; cathodic protection of the transmission main at petroleum pipeline crossings; and overall alignment selection. The discussion will also include the design of trenchless crossings under I-65 and other major roadways, creeks, and utilities.