Correction appended

A grease-clogged sewer line caused an estimated 600-gallon sewage overflow Thursday in Southwest Portland, authorities say.

Portland’s Bureau of Environmental Services said the overflow occurred in the 6700 block of Southwest Capitol Hill Road, just upstream from Stephens Creek Nature Park.

The public should avoid contact with the creek, especially in the area of the park, through Sunday, according to the bureau.

The sewage overflowed from a maintenance access hole onto Capitol Hill Road and into a storm drain leading to the creek.

Workers arrived about 7 p.m. and cleared the blockage about four hours later.

The bureau advised people to never pour grease down drains, as the liquid solidifies in pipes. People shouldn’t flush wet wipes down the drain, either.

The nature park covers 4.73 acres in the Willamette watershed.

-- Jim Ryan; jryan@oregonian.com; 503-221-8005; @Jimryan015

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A previous version of this report incorrectly stated the location of the overflow, due to a source’s error. The overflow occurred in the 6700 block of Southwest Capitol Hill Road, just upstream from Stephens Creek Nature Park.