Transmission Lines

The JWC sends water to each of its five member agencies through gigantic pipes called “Transmission Lines”.

Original Transmission Lines – Late 1970’s

Dig-Trans-in-Trench_smThe first major transmission lines were built in 1975 and continue to be used today. The City of Forest Grove is fed through a 24” line that runs directly from the WTP to Forest Grove. Water from Fern Hill Reservoir is gravity-fed from Fern Hill Reservoir through a 45-inch pipeline to the outskirts of Hillsboro. In 1979, a 42-inch pipeline was connected to the 45-inch line to deliver joint service to Hillsboro and Beaverton. In 1994, Tualatin Valley Water District joined the JWC and connected to this line as well.

Phase I Transmission Expansion – Early 2000’s

TransLine-copy_smA second 42-inch line connects to the 45-inch pipeline in Hillsboro and carries water north where it hooks into a 72” interconnect line called the North/South Intertie. The 72” carries the water north to a point where North Plains, a JWC wholesale customer, hooks up with their own distribution line. A 66” line hooks into the 72” from the east and is used to carry water to north Hillsboro and into TVWD.

Phase II Transmission Expansion – Mid 2000’s

Phase-II_smA new section of 72” pipeline was added that runs from the WTP through Cornelius to the 72” North/South Intertie. This addition more than doubled transmission capacity to meet increased demand and also created a looped transmission system. Looping provides redundancy for supplying water to Hillsboro, Beaverton and TVWD if an emergency shutdown of one of the lines occurs.