NIAGARA FALLS, N.Y. — Operators of a wastewater treatment plant that discharged a plume of stinky, black water near the base of Niagara Falls say they’re cooperating with investigators.

The Niagara Falls Water Board has said little publicly about the discharge that turned the water near the famous falls black Saturday, during a busy tourist weekend.

Mayor Paul Dyster says he’s disappointed in the lapse in communication.

The water board operates independent of city government.

In a statement Wednesday, the board said Executive Director Rolfe Porter has met with the state Department of Environmental Conservation as it, along with city police, investigates the discharge.

The water board says it emptied a sediment settling basin at its plant during the course of routine maintenance.