...S&P Global Ratings assigned its '##-' rating and stable outlook to Trinity River Authority (TRA), Texas' series 2018 revenue improvement bonds, issued for the Red Oak Creek system, a regional wastewater treatment system. At the same time, S&P Global Ratings affirmed its '##-' rating, with a stable outlook, on the authority's Red Oak Creek system's parity debt. We base our rating on the member cities' collective general creditworthiness and their contractual commitments to TRA. The cities receive a monthly invoice from the authority, with each billing composed of 8.3% of the budgeted operating costs and a fixed component that supports TRA's debt service on the Red Oak Creek system. The cities with the strongest relative credit quality are, in our view and in no particular order, are Cedar Hill, Desoto and Glenn Heights, which in total accounted for a little more than 64% of fiscal 2017 flows, or the physical volumes of wastewater conveyed to the authority. Flows are the major determinant...