The day after he received a major award for blowing the whistle on a billion-dollar Army Corps of Engineers construction project on the Mississippi River, Donald Sweeney was at it again yesterday, saying the Corps is still trying to overstate the value of expanding locks on the waterway.

Sweeney, an economist and 25-year civilian veteran at the Corps, was among nine public servants receiving the first "Service to America" awards Wednesday night for publicly alleging in 2000 that he had been removed as head of a Mississippi River study for refusing to use suspect data at the behest of his bosses. The awards for federal employees were sponsored by the Partnership for Public Service and the Atlantic Media Group.

Yesterday, Sweeney alleged at a Capitol Hill news conference that the Corps has simply gone back to using an antiquated economic model that fails to consider alternatives to moving grain on river barges, thereby overstating the need for lock expansion. He appeared at the news conference, sponsored by Environmental Defense, despite what he called a Corps "gag order" advising him not to speak on the issue.

"What the Corps has done is actually make the study even worse than it was with cooked numbers," Sweeney said.

Robert M. Andersen, the Army Corps of Engineers' chief counsel, responded that the Corps has restructured its study with an appropriate model and included the Environmental Protection Agency and other federal agencies in the review.

"We have made every attempt to look at all the options, and we are doing it with our federal partners in the open," Andersen said.

He and other Corps officials, meanwhile, confirmed that Dominic Izzo, principal deputy assistant secretary of the Army for civil works and a top civilian overseer of the Corps, had resigned Nov. 6 for personal reasons.

Izzo, a former engineer officer in the Army, left the Corps and worked as a senior Enron Corp. executive before returning to the Corps as a member of the Bush administration. Izzo has not been linked to the financial irregularities that have engulfed Enron, and acquaintances inside and outside the Corps say his departure was unrelated to the Enron scandal.

While Izzo should have been in position to replace Michael Parker, who was forced to resign in March as the Corps' top civilian official for failing to support President Bush's budget, Izzo apparently lacked the reform credentials desired by the White House for overhauling the troubled agency.

"Whatever you could say about Dom Izzo, and there are a lot of good things you can say about him, I don't think he saw shaking up the Corps as part of his job," said Scott Faber, a water resources specialist at Environmental Defense, a nonprofit environmental group.

Faber called the economic model now being used by the Corps in its restructured study an "insult" to the Army's inspector general and the National Academy of Sciences, which investigated Sweeney's allegation and determined that the Corps had tried to skew its original study in favor of expanded locks.

"The political leadership of the Corps of Engineers continues to use bad math to justify projects that could not pass a credible cost-benefit analysis," Faber said.

Jeff Stein, a senior policy analyst at Taxpayers for Common Sense, said the Corps' economic model assumes that farmers will continue shipping grain by barge on the Mississippi no matter how high barge rates escalate and despite numerous alternatives, including rail transit and ethanol processing.

Donald Sweeney, an Army Corps of Engineers economist, blew the whistle on a Corps construction project.