The Portland Water Bureau operates a well field capable of producing close to 100 million gallons per day of high quality drinking water. The Columbia South Shore Well Field (CSSWF) is the second largest water source in the State of Oregon, with about half of the daily capacity of Portland’s Bull Run source. Groundwater from the CSSWF is used as an emergency back up for customers served by the Bull Run supply and also provides supplemental supply during the summer high demand season.

The Columbia South Shore Well Field:

• Can provide 82-102 million gallons a day of drinking water from 27 wells
• Meets or exceeds all state and federal drinking water standards
• Is ideally located to serve as the secondary source of Portland’s drinking water
• Allows Portland to maintain Bull Run as an unfiltered drinking water source
• Supplies water during emergencies or to augment Bull Run supply in the summer
• Is protected from contamination by the Groundwater Protection Program which requires businesses that use harmful chemicals to implement best management practices to prevent spills
• Spans three cities: Portland, Gresham and Fairview

To access groundwater, wells are drilled into aquifers. Portland groundwater supplies are tapped from three regional aquifers.