Neighborhood Notes

The Portland Water Bureau turned off its groundwater supply system this morning. The system has supplied Water Bureau customers with drinking water since high levels of turbidity forced the bureau to turn off its primary Bull Run water supply last week.

"This was an unusual run of groundwater." said Water Bureau Administrator David Shaff. "When intense rain in the Bull Run causes excessive turbidity, that rain is generally followed by more rain which flushes the turbidity out. In this case, there was no more rain, so the levels of turbidity in the watershed remained above acceptable serving levels. Flushing has taken a bit longer than normal."

While both of the bureau's water sources, the Bull Run watershed and the Columbia South Shore Well Field (CSSWF) meet and exceed all federal drinking water standards, the bureau relies primarily on the Bull Run source to provider customers with drinking water. The CSSWF is maintained as an emergency back-up for events similar to what the watershed experienced last week and for seasonal supply augmentation.

To enhance operational flexibility as part of the bureau's Habitat Conservation Plan, the bureau intends to install a variable level intake system by 2014. This system will allow the bureau to pull water from varying depths of water, as opposed to the current intake system which only pulls from the bottom of Bull Run's reservoir 2.

"In this case, had the variable level intake system been available for our use, said Water Bureau Operations Manager Chris Wanner, we could have pulled less turbid water from shallower areas. Since we only have the option to take water from the bottom at this point, our ability to mitigate turbidity events like we experienced last week is poor."

Jennie Day-Burget

Public Information Officer

jennifer.day@ci.portland.or.us