City officials said there will be $5 million more in the city treasury this year as a result of lower workers' compensation costs and closing the books on some old expenses.

Mayor Mufi Hannemann yesterday praised city workers for cleaning up the accounting books by determining that $3.1 million in old purchase orders could be canceled, freeing that money for other expenses.

Hannemann also said city officials have cut workers' compensation expenses to $12.5 million this year from $14.5 million the year before.

And he praised safety programs, employees and others for getting people back to work earlier, so they are more productive.

City Budget and Fiscal Services Director Mary Pat Waterhouse said that going back through old purchase orders that were not actually spent showed that some of the unused money had been tied up for more than 10 years.

Waterhouse said the money came from a variety of sources: from equipment purchases to consultant contracts on design and construction projects. "It's all over the place," she said.

For example, she said the city may have issued a purchase order for a $20,000 consultant contract but needed to spend only $15,000 by the time the work ended. By clearing the books, that $5,000 can be returned to the general fund.

Hannemann also announced that the city has given the state an amphibious excavator used to clear Salvinia molesta, a noxious weed, out of Lake Wilson in 2003. He said the 31-ton Caterpillar backhoe on pontoons cost the city $496,121.

The city hopes that turning over the backhoe might help smooth the way for the state to take responsibility for Kawai Nui Marsh in a move that requires joint cooperation between the two branches of government.

Hannemann said that Gov. Linda Lingle sent a thank-you letter for the transfer.

"Allowing the state to own the excavator will streamline the process of sharing it between cooperating agencies and will have a positive impact on the management of endangered water bird species, flood control and law enforcement," she said.

The city transferred the excavator last month from the Halawa Corporation Yard to a state location in Waipahu next to Pouhala Marsh. The move cost the city $5,000.

Hannemann said, "we hope this helps the state also fulfill its obligations concerning the maintenance of the wildlife habitat of Kawai Nui Marsh in Kailua."

Reach Robbie Dingeman at rdingeman@honoluluadvertiser.com.