ANNAPOLIS -- State legislators have renewed the debate over whether Maryland's temporary ban on phosphate detergents should be made permanent next year.

Del. Lawrence A. LaMotte (D-Baltimore County) has prefiled a bill to erase the expiration date and make the ban permanent.

Sen. Gerald W. Winegrad (D-Annapolis) said six Economic and Environmental Affairs Committee members have agreed to cosponsor a similar bill in the Senate.

Six member signatures are enough to get the bill out of committee, where Winegrad's initial proposal died in 1984.

A recent state study shows that phosphates coming from waste treatment plants have been reduced as much as 21 percent since the ban took effect.

"What's happening is pretty overwhelming," LaMotte said of the report released by the Department of Environment Water Management Administration.

"There have been substantial reductions in the levels of phosphates going into the bay, and there's not been one complaint from anyone other than the industry," he said.

However, Del. Anthony M. DiPietro (D-Baltimore) said he questions whether the ban really is helping the bay.

The state report indicates only that waste treatment plants are saving money, more than $12,000 daily, from having less phosphate to treat, DiPietro said.

The report does not show that the bay is healthier and that more fish or submerged aquatic vegetation are living, he said.

While Maryland is actively working to improve the bay, DiPietro said he thinks much of the problem is coming down the Susquehanna River from Pennsylvania.

Del. William A. Clark (R-Harford) said phosphate reduction indicated in the state report might be a result of weather rather than the ban.

The report compares treatment plant effluents before the ban with those in 1986, one of the driest years in recent history, he said. During dry weather, less runoff affects groundwater infiltration, and that may mean less phosphate, he said.

Lobbyists for the soap and detergent industry argue that nonphosphate detergents do not clean as well and are more costly.

Winegrad and LaMotte criticized opponents of the extension.

"I think {their arguments are} absolutely ridiculous," Winegrad said. "They're arguments that have been fostered by the industry. They mean that unless you can show a benefit from spending $22 million on agricultural programs, we should just let them go, too."