Swimming was banned.Ĭitizens took action. The untreated sewage also carried disease-causing bacteria and other contaminants into the river. Pollution had robbed the river water of nearly all its oxygen. By the mid-1930s, salmon fingerlings placed in the river died within 15 minutes. Tests in 1927 showed that the Willamette flowing through Portland was severely polluted. In the early 20th century, public concerns about water pollution and public health increased. By 1933, larger pipes made of concrete or brick extended the system to 1,100 miles of pipe that conveyed sewage directly into the Willamette River and the Columbia Slough. By 1883, the City had installed 15 miles of terra cotta pipe ranging in diameter from 9 to 18 inches. Over the following years, the collection system grew. Built in 1864, this simple system collected sewage from homes and businesses and carried it directly to the river. Portland's first sewer was a covered wooden trough that ran down Southwest Montgomery Street from Fourth Avenue to the Willamette River. View Less Evolution of Portland Wastewater Treatment