NEW YORK (Standard&Poor's CreditWire) May 22, 2001 – Standard&Poor's has assigned its single-'A'-plus rating to Washington County, Md.'s $12.69 million public improvement bonds series 2001 due Jan. 1, 2021. The outlook is stable. In addition, Standard&Poor's affirmed its single-'A'-plus rating on the county's outstanding public improvement bonds and its single-'A'-plus underlying rating (SPUR) on the county's outstanding public improvement bonds series 1998, 1999, and 2000, and taxable water and sewer refunding bonds series 1999. The rating is based on the full faith and credit pledge of the county and reflects: -- Steady tax base growth, -- Sound finances and reserve levels, and -- A moderate debt burden. Tempering factors include the ongoing state-mandated requirement