SAN FRANCISCO (Standard&Poor's) April 11, 2013--Standard&Poor's Ratings Services raised its underlying rating (SPUR) to 'A' from 'A-' on Burton Elementary School District, Calif.'s existing certificates of participation (COPs). At the same time, Standard&Poor's assigned its 'A' long-term rating on the district's series 2013 COPs. The outlook on all ratings is stable. "The rating reflects our view of the district's improved financial management practices and consistently strong reserve levels," said Standard&Poor's credit analyst Kate Parmer. "The ratings further reflect our view of the district's strong income indicators on a household basis and low to moderate debt levels," Ms. Parmer added. The 9.5-square-mile district serves an estimated population of 17,800 and is located in