Stoking the fires of the Midwest’s most contentious environmental issue, the U.S. Fish and Wildlife Service and the Army Corps of Engineers agreed yesterday that the flow of water in the Missouri River should be increased in the spring to save fish and birds from extinction. Gen. Carl Strock became the first Corps official to publicly endorse a “spring rise” in the river to protect the pallid sturgeon, piping plovers, and least terns from extinction, though he said any changes in river flow would not be fully implemented until 2003. But Sen. Christopher Bond (R-Mo.), an ally of farmers and barge owners who would be hurt by the spring rise, said he would lobby Texas Gov. George W. Bush to reverse the decision should he become president.