Standard&Poor's Ratings Services assigned its 'BBB-' underlying rating (SPUR) to Brazoria County Municipal Utility District (MUD) No. 21, Texas' series 2008 unlimited tax general obligation (Go) bonds. The SPUR reflects the district's: High overall net debt burden; Adequate financial position, but below average by special district standards; and Elevated tax rate. These factors are offset, in part, by the district's: Advanced status development; and Very strong wealth and income levels, which are boosted by the MUD's participation in the Houston metropolitan statistical area (MSA). An unlimited ad valorem tax pledge secures the bonds. Officials will use bond proceeds to make general improvements to the existing water, sewer, and drainage infrastructure. The district, with an estimated population of 3,400,