Standard&Poor's has placed its 'A-' underlying rating (SPUR) on Maricopa County's multifamily housing revenue bonds series 1999A on CreditWatch with negative implications. The bonds were issued on behalf of the Metro Gardens and Mesa Ridge Apartments project, two affordable multifamily housing developments in Phoenix, Ariz. The key factor driving the rating action is the possibility that debt service coverage on the senior, rated bonds may have dropped, suggested by the owner's report that it may draw on the debt service reserve fund for the subordinate, unrated bonds (series B) in order to pay debt service on those bonds. Additionally, the owner has reported very low occupancy at the project. Standard&Poor's has not yet received financial statements,