Standard & Poor's Ratings Services assigned its 'BBB-' rating, and stable outlook, to Harris County Municipal Utility District (MUD) No. 188, Texas' $4.34 million series 2003B unlimited-tax GO bonds. The rating reflects the district's: High total debt, and Moderate property tax base concentration. Factors that moderate these risks include the district's: Participation in the Houston MSA, boosting wealth and income levels; Good reserve levels; and Essentially complete status of development. An unlimited ad valorem property tax secures the bonds, which will be used to refund various maturities of the district's series 1994 bonds outstanding. MUD No. 188 is about 26 miles northwest of Houston, Texas' central business district, with easy access throughout the entire MSA. Entirely within Houston's extraterritorial jurisdiction,