Jefferson County (Ala.) has finalized an agreement with Ambac Assurance Corp. as the county works its way through its $4.2 billion bankruptcy, according to the county's top executive, the Birmingham Business News reported today. The agreement involves nearly $90 million in debt associated with the construction of the county's courthouse in Bessemer. The courthouse project involved the creation of a building authority to which the county agreed to allot annual lease payments of $8.3 million to pay off the $89 million in warrants. New York-based Ambac insurers those lease payments. Jefferson County CEO Tony Petelos said the deal, officially completed Wednesday, will reduce those payments to trustee First Commercial Bank to $1.2 million this year. The payments will rise to and level off at $5 million in three years, he said.