The Army Corps of Engineers has found a new way to create oyster beds, but its safety is coming into question.

The Corps obtained slag, a byproduct of steel manufacturing, and placed it in the Severn River, a tributary of the Chesapeake Bay, to stimulate oyster production last December. Slag is believed to have high levels of pollutants.

Environmentalists raised concerns about the dangers to the bay, and now federal agencies have agreed to regulate the use of slag, specifically testing the areas where slag has already been placed.  Severn Riverkeeper Fred Kelly said in an interview with the Annapolis Capital that “we would have preferred they’d done the testing before they put the slag down in the Severn River.”

Claire O’Neill, a spokesperson for the Army Corps of Engineers, told the Capital that monitoring already was planned for the area containing the slag, but after meeting with environmentalists, “we’re going to change the protocols a little bit.”

Typically, baby oysters are grown on beds of old oyster shells, but there has been a shortage in available shells.

The Corps hopes to lay the first slat, or baby oysters, on the slag this summer. Harvesting will not be permitted on the reef.