Butler County could have made more money by investing wisely, according to county Controller Jack McMillin.

He said at Tuesday's county prison board meeting the county borrowed money allotted for projects such as the new prison and invested it at a low interest rate.

"What it amounts to is lost revenue for the prison project," McMillin said.

The county in 2003 borrowed $50 million to pay for projects, including the new prison being constructed on South Washington Street.

To help offset the costs of these various projects, the county in 2003 invested $30 million with Sky Bank.

McMillin said the county only earned a 3 percent interest on the money when it could have been receiving a higher rate sooner.

The county lost $300,000 annually, or around $1 million total, in potential revenue, he said.

County Treasurer Diane Marburger said later Tuesday the Sky Bank investment was locked in at the 3 percent rate because the county did not have a date when it needed to draw on the money.

The county borrowed and invested money without knowing when it would be spent as there was no construction schedule; a site had not been selected yet.

"We borrowed the money prematurely," Marburger said.

Although the money could have been reinvested at any time, the county could not receive a better interest rate until awarding the rest of the prison construction contracts in January, which led to a completion date, she said.

McMillin previously had complained about the county borrowing the $50 million before the commissioners selected a prison site.

Bill O'Donnell, chief county clerk, disagrees that the $50 million should have been borrowed later. He said later on Tuesday the prison was not the only project being funded and the other work, including the new county communications center, was under way much sooner.

O'Donnell said the interest rates for borrowing were so low in 2003 that the county could not pass up the opportunity to borrow then. Just as the county would pay lower interest rates on borrowed money, it would receive lower interest rates on invested funds, he said.

However, the county still did make money from the Sky Bank investment. Marburger said the interest earned is $1.5 million.

The county earlier this year closed the Sky Bank account and reinvested the now $32 million with Citizens Bank at a 5 percent interest rate.

The financing aspect of the prison project is not the only issue McMillin has complained about in the past year. He also challenged the $36 million construction cost of the prison, saying it would be $40 million.