Standard&Poor's Ratings Services assigned its 'AA+' rating to the City of Tacoma, Wash.'s series 2011 sewer revenue refunding bonds and affirmed its 'AA+' rating on the city's sewer system's debt outstanding. The outlook is stable. The rating reflects our view of the following credit strengths: A sound and diverse service area economy; A good operational history of the sewer and surface water systems; A strong revenue collection process, with the legal ability to place liens upon property for delinquent accounts; and Good financial results, reflected by solid coverage of annual debt service and a strong liquidity position. The bonds are secured by the pledge of net revenues of the sewer system, which is made up of two utilities: