Salem’s Water Source

​​The North Santiam River watershed provides Salem’s drinking water. A watershed is the area of land within which all the rainfall and snowmelt reach a common body of water​—a stream, river, lake, wetland, or aquifer. The reason we talk about a watershed, and not just the river, is that the way land is used in the watershed affects the quality and quantity of water it produces.

Highlights of Salem’s water source

Some key points about the North Santiam River watershed include:

  • Size: Salem’s watershed covers more than 490,000 acres of land stretching from the Cascade Mountain peaks of Mt. Jefferson and Three-Fingered Jack to the City's water intake above Stayton.

  • Management: Approximately 80 percent of the land in the watershed is owned and managed by the United States Forest Service, Bureau of Land Management, and the Oregon Department of Forestry.

  • Uses: The agencies manage for multiple uses including timber harvest, recreation, and water resources. Land use in the entire watershed is a combination of wilderness, lumber, recreation, agriculture, and rural residential.

  • Communities: A few small communities are located along the river. The combined population of Gates, Idanha, Detroit, and Mill City is about 2,700.

Aquifer storage

Salem is growing and with it the demand for water. The question is, how to find a second reliable water source without damaging the environment and creating huge costs to the rate payer. Salem is one of a growing number of cities in the United States going underground for the answer. An Acquifer Storage and Recovery System (ASR) system was identified in the City’s Water System Master Plan as the preferred new secondary water source.

The volcanic action of 17 million years ago has created just the right conditions for water storage beneath the South Salem Hills. The cavities between the jumble of rocks formed by the Columbia River Basalt Lava Flows hold water much like an irregular honey-comb contains honey. The ASR system uses the latest technology to pipe treated drinking water from the North Santiam River during winter into the aquifer where it is stored. When summer brings peak demands, or during an emergency, the water is recovered by pumping it back out of the aquifer.

The North Santiam River will remain the City’s primary water source, but the capacity to treat and deliver the water to Salem is going to be expanded. The ASR system will continue to play a vital role by allowing high river flows in the winter to be stored underground for use in the summer.