Federal wildlife managers say more than 30 ducks and geese have died after they came in contact with cooking oil waste in a flood retention pond in Lakewood.

The U.S. Fish and Wildlife Service said Monday the birds ingested the oil or absorbed it through their skin. The first dead birds were found Jan. 20.

Officials believe the commercial cooking oil was dumped upstream from the pond starting about Jan. 18. The pond collects runoff from residential and commercial neighborhoods.

The Fish and Wildlife Service asked for the public’s help in finding whoever dumped the oil. Ducks and geese are protected by state and federal laws.