Water Supply Facilities in the Bull Run Watershed

Between 1904 and the early 1960s, the city added major elements to the original system: storage reservoirs, a modern headworks facility, and transmission conduits.

Storage Reservoirs

In 1929, the Portland Water Bureau completed construction of Bull Run Dam 1, a concrete gravity arch dam. Dam 1 impounds Reservoir 1 (also known as Lake Ben Morrow). The maximum storage capacity of Reservoir 1 is 9.9 billion gallons. In 1962, the bureau completed Bull Run Dam 2, an earthfill dam. The maximum storage capacity of Reservoir 2 is 6.8 billion gallons. Although the combined total capacity of both reservoirs is approximately 17 billion gallons, the total useable storage in Reservoirs 1 and 2 is closer to about 10 billion gallons.

Releases from the reservoirs are controlled to ensure that water quality meets federal and state drinking water standards for unfiltered water systems.

Headworks Facility

Headworks is the Portland Water Bureau's facility at the "head" of the water source where water is first diverted, treated, and routed into the distribution system. At Headworks in Bull Run, operators treat the water with chlorine, a disinfectant. As the water flows into town, operators add ammonia and sodium hydroxide to the water. The ammonia prolongs the effectiveness of the chlorine, a process called chloramination.

Transmission Conduits

From the Bull Run watershed, water flows by gravity through large conduits to the 50-million gallon underground reservoir at Powell Butte Nature Park in Portland. Using gravity to move water reduces the need for pumping which requires a lot of energy.

Related site:

History — including conduit construction