The City of Portland has had more than 20 sanitary sewer overflows over the past five years that have reached waters of the US, and over 80 that have affected public and private property. By requiring the implementation of an operations and maintenance plan as well as the continued efforts at combined sewer overflow abatement with this Order, it is expected that the number of SSO events per year will decrease significantly and therefore the gallons of raw sewage reaching US navigable waters (including fragile ecosystems and public beaches) will also decrease.