(Portland, OR)  --  Officials are urging people to avoid contact with the Willamette River, from south of the Sellwood Bridge to near Kelley Point Park.  The Bureau of Environmental Services says yesterday's heavy rainfall caused the city's sewer system to overflow into the river. The Bureau says the overflow is contaminated with untreated sewage.  People who do have contact with river water within 48 hours of issuance of the advisory are urged to wash their hands thoroughly.