Federal officials have upgraded Lawrence’s flood control rating — and reduced flood insurance premiums here — saying city efforts to restrict floodplain development have made the entire city safer.

“This saving is a tangible result of the flood mitigation activities your community has implemented that protect lives and property,” David Maurstad, acting director of the mitigation division at the Federal Emergency Management Agency, wrote in letter to the Lawrence City Commission.

The improved rating will result in a 10 percent discount for policies issued or renewed by the National Flood Insurance Program after Oct. 1, officials said. Those savings could average about $40 a year for Lawrence property owners.

“You know, it’s one of the things we believed we could accomplish with better floodplain regulations, and we delivered on that,” said Commissioner David Dunfield, who was one of the most vocal proponents of the regulations.

But Bill Yanek, director of governmental relations for the Lawrence Builder-Realtor Coalition, said there were hidden costs associated with the new regulations. Property owners near the floodplain have paid as much as $500 for certification to ensure they’re not subject to the rules.

“We’re certainly pleased with the decrease in floodplain insurance premiums — but citizens should be aware there’s an increase in costs just from the potential of being in the floodplain,” Yanek said Monday.

The regulations were adopted by the Lawrence City Commission in October 2002 and went into effect in January 2003.

They require builders to do a hydrological study showing their development wouldn’t expand the floodplain. The rules apply only to properties already designated by FEMA as part of the 100-year floodplain. Those studies, developers say, typically cost between $3,000 and $5,000, depending on the size and location of the lot under development.

The result of the new regulations, Yanek said, has been that “development in the actual floodplain is not happening.”

Federal law mandates lenders pay for insurance on properties in the 100-year floodplain. City officials say that in 2003 there were 420 flood insurance policyholders in Lawrence, who paid an average of $399 per year. The new rating, then, would result in a nearly $40 average discount.

City commissioners will discuss the FEMA rating at their meeting at 6:35 p.m. today in City Hall, Sixth and Massachusetts streets.