AUSTIN, Texas--(BUSINESS WIRE)--Fitch Ratings assigns its 'AAA' rating to the following Lewisville, TX's (the city) waterworks and sewer system revenue bonds: --$12.1 million waterworks and sewer system revenue refunding and improvement bonds, series 2015 The bonds are scheduled to sell on July 20. Proceeds will be used to refund certain outstanding obligations for debt service savings, and to finance improvements to the city's waterworks and sewer system. In addition, Fitch affirms its ratings