PORTLAND, Ore. (AP) — Portland city officials say an estimated 60,000 gallons of storm water and sewage overflowed into the Willamette River following weekend heavy rains.

The Portland Bureau of Environmental Services characterized the estimate of the combined sewage overflow Saturday as preliminary. It defines a combined sewer overflow as about 80% storm water and 20% sewage.

The agency, in a release, said the number of such overflows has dropped by 94% to the Willamette River since the completion in 2011 of a $1.4 billion project aimed at reducing such incidents.

The agency said people should avoid contact with the river downstream and in other areas until late Monday due to increased bacteria in the water.