Transmission & Distribution
The Commission is responsible for the construction and maintenance of more than 490 miles of water mains, not including the Big Butte Springs lines. The water mains that come from the pumping stations are called feeder mains and vary in size from 24 to 48 inches in diameter. The feeder mains supply water to the service mains, which vary in size from 2 to 24 inches. The service mains carry the water to more than 500,000 service connections throughout the valley. The distribution system consists of these water mains and service lines plus valves, fire hydrants, and meters. Pipeline materials consist primarily of ductile iron and cast iron. New pipelines are constructed of ductile iron only.
The Water Commission installs, operates and maintains more than 10,773 valves in a vast underground grid of water mains and service connections. The valves regulate the flow of water through the mains and allow service crews to shut off water to a specific area and isolate a problem for repair or improvement. As a result we are able to limit the number of homes and businesses adversely impacted by a water main project.
The elevations of the Big Butte Springs intakes vary from 2,650 to 2,700 feet. Water flows by gravity from the springs to Medford in two transmission lines, each having a capacity of 13.2 mgd for a combined daily capacity of 26.4 million gallons. The first of these two water lines went into service in 1927 and the second in 1951. Both are welded steel pipelines varying in size from 20 inches to 30 inches and averaging 24 inches in size. Both lines are underground throughout their entire 30.5-mile lengths. The energy from approximately 1,100 feet of elevation difference is dissipated in friction loss resulting from moving such a large quantity of water through the pipelines.
The Big Butte Springs transmission lines are located on different routes, and each passes over approximately 75 different mountain summits. Pressure in the lower reaches is automatically controlled to maintain a full pipe by means of special backpressure control valves.
The Rogue River supply transmission mains transport water from the Robert A. Duff Water Treatment Plant to the City of Medford. The Table Rock Road transmission main consists of five miles of 30 and 42-inch ductile iron pipe. A second transmission main from the Rogue source consists of a 36-inch ductile iron pipe. There is also a 36-inch transmission main on the westside of the service area.
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