S&P Global Ratings raised its long-term rating on Oak Grove, Mo.'s general obligation (GO) bonds to 'A+' from 'A'. We also assigned our 'A' rating to the city's series 2017 certificates of participation (COPs). The outlook on both ratings is stable. The raised rating reflects improvement in the city's unassigned general cash balance, which is above $500,000. The COPs are secured by annual lease rental payments payable from legally available funds, subject to annual term renewal. The city plans to use certificate proceeds to fund improvements to its sewer treatment plant, construction of an interceptor line, and other improvements to the sewer system. Management reports that the city intends to pay the certificates from sewer system revenues. The 'A' rating