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Fall Color Season in the Bull Run Watershed

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As a result of the recent heavy storms in the Bull Run, Portlanders may notice that their water has taken on a subtle tea color. This is a normal change that can occur in fall and winter due to organic materials that have washed into the Bull Run storage reservoirs. Heavy rains early in the fall and winter are responsible for carrying materials into reservoirs and streams before the water is treated.

Our drinking water is treated but not filtered, which is why you may see color at your tap water or staining the filters in your business or home. Learn about upcoming changes to how Bull Run water is treated including the building of a filtration plant by 2027.

What causes “fall color?”

The color is produced by tannins found in the organic materials, like the color you might see in a cup of tea. Tannins do not produce any negative health effects nor do they change the quality of Portland’s water. The length of the fall color season depends on the strength and duration of the rains and the amount of organic material that is carried into the system.

As always, the Portland Water Bureau constantly monitors the water entering our distribution system to continue to meet all state and federal drinking water standards. Customers will be notified of any changes to water quality safety if they occur.

Any questions may be directed to the Water Quality Information Line at 503-823-7525