The Water Bureau will rely on the secondary source as long as weather conditions and water quality dictate.

The Portland Water Bureau turned off the Bull Run water supply system this morning due to increased turbidity in the watershed. The bureau activated groundwater wells in the Columbia South Shore Well Field to temporarily serve water to Portland. Recent heavy rains and increased stream flows in the Bull Run watershed have contributed to this rapid increase in turbidity. Turbidity is a measurement of the cloudiness of (drinking) water by suspended particles. Portland is one of six large drinking water systems in the country that does not filter its water supply. The city is able to comply with federal drinking water regulations by continuously meeting a set of filtration avoidance criteria.

Portland has been able to consistently meet these criteria, but it occasionally has to shut down the Bull Run system and operate from its backup groundwater supply when storms and other natural disturbances in the Bull Run reservoirs increase the turbidity. The Surface Water Treatment Rule requires that the city not serve drinking water exceeding a turbidity level of 5 Nephelometric Turbidity Units (NTU). "Stream levels rose rapidly overnight resulting in a spike in turbidity at Headworks (treatment facility). Although stream levels have crested, turbidity levels continued to rise through the morning. We are taking this proactive step to ensure that we continue to serve the high quality water that we strive to provide." said Water Bureau Administrator David Shaff.

"Activating the Well Field allows us to continue providing extremely high quality drinking water to our customers despite turbid conditions in the watershed." The Columbia South Shore Well Field is a high quality water supply which meets or surpasses all federal and state drinking water regulations. The Water Bureau will run the Well Field as long as weather conditions and water quality dictate. The Water Bureau's Web site (portlandonline.com/water) provides further information about both the Bull Run and the Columbia South Shore Well Field under the "Portland's H2O" tab.