SAN FRANCISCO (Standard&Poor's) Feb. 22, 2007-- Standard&Poor's Ratings Services assigned its 'AA-' rating to Portland, Ore.'s 2007A first-lien sewer revenue refunding bonds and raised its rating and underlying rating (SPUR) to 'AA-' from 'A+' on the city's outstanding senior and subordinate sewer system debt. The outlook is stable. The raised rating reflects successful completion of the system's West Side Tunnel project -- a significant component of city's sizable combined sewage overflow (CSO) remediation project, begun in 1991 and scheduled for completion in 2012 -- coupled with strong debt service coverage, successful funding of a sizable rate stabilization fund, and solid additional cash reserves. To date, the city has managed this project on time and on budget