NIAGARA FALLS, N.Y. - Officials in upstate New York say excess sewer water again made its way into the Niagara River after a high-profile discharge of black-coloured water last summer.

The Niagara Falls Water Board says it reported to the state Department of Environmental Conservation that excess sewage was discharged on Wednesday.

WGRZ-TV reports state officials said in a statement that the discoloured water is "wholly unacceptable."

Officials say the water board must immediately make corrections. The DEC's maximum penalty for water quality violations are US$37,500 per day.

The water board says it has no way of controlling the colour of overflow discharge during a wet weather event.

In late July, a discharge of foul-smelling water from the board's wastewater treatment plant turned the water near the base of Niagara Falls turned an alarming shade of black.