A series of Harford County bonds recently received triple-A ratings from three national bond-rating agencies, the highest designation ever received by the county.

The bonds were upgraded from "Aa" to "Aaa" by Moody's Investors Service, from "AA" to "AAA" by Fitch's Investor's Service and from "AA" to "AAA" by Standard & Poor's.

The ratings affect $33.8 million in general obligation bonds and tax-backed water and sewer bonds that are being refunded by proceeds of a sale last fall to take advantage of lower interest rates.

County Treasurer James Jewell said county officials are "overjoyed. The higher rating reflects the confidence of the investment community in Harford County."

The triple-A ratings, the top investment grades issued by the bond houses, mean the county's bonds are good-quality investments, Mr. Jewell said. They will allow the county to borrow money for capital projects, such as schools and roads, at lower interest rates.

The refunded bonds received the high ratings because they are backed by secure U.S. government obligations, Mr. Jewell said. In Harford's case, those obligations are U.S. Treasury notes, held in an escrow fund that cannot be touched. That guarantees payment of the bonds when they become due, he said.

The bonds, which were issued in 1988, 1990, 1991 and 1992, have 10-year call dates.