...Standard & Poor's Ratings Services assigned its '##' rating to Houston's series 2015C and 2015D combined utility system (CUS) first-lien revenue refunding bonds. At the same time, Standard & Poor's affirmed its ratings on all CUS-related debt issued by either the city or the Coastal Water Authority on the city's behalf. The outlook, where applicable, is stable. The bonds are secured by net CUS revenues, but are subordinate to the lien securing the previous ordinance bonds. The system has roughly $6.1 billion in total outstanding debt, roughly $140 million of which is related to the previous ordinance, which we rate '##+'. We understand the 2015C bonds will be privately placed with Citigroup, and used to refund for savings portions of the system's parity series 2007A revenue bonds. The series 2015D bonds will be used to refund various maturities of multiple system parity revenue bond series, also for interest rate savings purposes. The ratings reflect our assessment of the system's:...