On Tuesday, July 22nd, the Portland Water Bureau announced it had begun adding groundwater from the Columbia South Shore Well Field to the City’s Bull Run-sourced drinking water. Officials are making this change primarily due to prolonged dry conditions, warm temperatures, and the limited precipitation forecast this season. The Bureau explains that blending Portland’s two sources extends the water supply through the summer season, ensuring water users maintain access to high-quality drinking water until rainwater replenishes the Bull Run watershed.
This announcement marks the earliest summertime supply augmenting activation of the city’s well water system since 2019. In recent years, this has occurred as early as August, due to dry springs and early summer weather reducing the supply at Bull Run. The October 2023 to April 2024 water year, which had near-average rainfall and a suitable mountain snowpack, kept Portland’s watershed supplied for a significant portion of the dry season lasting into October. However, warmer weather patterns and increased water usage have made well-water sources integral to the regional water supply. The Water Bureau’s “Seasonal Water Supply Augmentation and Contingency Plan” guides the Bureau’s annual addition of groundwater to slow the drawdown of the Bull Run reservoir. This augmentation preserves the watershed supply throughout the dry season and supports year-round water usage for fish habitat, which also relies on water flow from Bull Run.
Columbia South Shore Well Fields tap into deep aquifers filled with rainwater throughout the year. Portland Water Bureau assures residents that Portland’s groundwater supply meets or surpasses all federal and state drinking water regulations. However, the Bureau’s policy is to notify the public when activating groundwater sources so sensitive water users can take precautions. It can take up to two weeks before residents receive blended water. After operators revert to entirely Bull Run-sourced water, customers can expect it to take another two weeks for the lines to clear of groundwater.
Sensitive water users can sign up at the Portland Water Bureau’s website to receive notifications regarding changes to the water system. Customers with questions should call the Water Line at 503-823-7525 and check this article for updates when Portland’s water system returns to 100 percent Bull Run watershed-sourced water.
Update October 22, 2025: The Portland Water Bureau announced it returned its water supply source to 100% Bull Run-sourced drinking water. Customers can expect another two weeks for supply lines to completely clear of the blended Bull Run and groundwater mixture.
