The independent credit risk research group Standard & Poor's Ratings Services raised its rating on the Colleyville's waterworks and sewer system revenue refunding bonds to AAA, reflecting the system's stability and low debt level, according to the S&P report.

City spokesperson Mona Gandy said S&P typically reaffirms or upgrades bond ratings every two to three years and had already rated Colleyville's general obligation and drainage utility bonds as AAA, the highest available bond rating. With the upgrade, Colleyville joins Arlington as the only Texas cities to have three AAA bond ratings.

"Achieving a third AAA rating is a testament to the hard work by city leadership and staff to manage our projects and budgets effectively," said Mayor David Kelly in a press statement. "It allows us to do more with our tax dollars, and that's good for Colleyville citizens and businesses."

The report said the bond was raised from AA+ as a result of a stable, long-term water supply that requires moderate water and sewer rates and adds limited capital needs.

For Colleyville, this means it can borrow money at lower interest rates when issuing debt, or refinancing existing debt, for city capital projects, which saves money for the taxpayer, Gandy said.

S&P's report expects that the city's waterworks and sewer systems debt level of $2.1 million in revenue bonds will be paid off by 2018.