NIAGARA FALLS, NY - Investigations are underway into the inky, stinky, black discharge of sewage near the base of the world famous Niagara Falls over the weekend.

What looked to some like a massive oil spill occurred on Saturday afternoon, during one of the busiest weekends for tourism—the life blood of the Falls’ economy.

By Sunday the sewer discharge and the discoloration of the water in the lower Niagara River had dissipated.

In a statement issued Monday, the New York State Department of Environmental Conservation confirmed that it had “responded to complaints of discolored water and odors near Niagara Falls State Park, and is continuing to investigate a discharge from the City of Niagara Falls wastewater treatment plant into the Niagara River. The investigation is ongoing and additional information will be provided as it is available.”

Also on Monday, Dan O'Callaghan, installed as Chairman of the Niagara Falls Water Board in January, told WGRZ-TV there will be a full investigation of the matter, and expressed confidence the DEC will find that his agency did not violate any terms of its discharge permits.

Niagara Falls Mayor Paul Dyster –who appoints some of the members of the Niagara Falls Water Board, is away on vacation. However, a city spokesperson said the administration is “disappointed” with the timing of the release and the lack of any heads up to city officials that it was about to occur.

The discharge, which entered the water from a tunnel not far from the Maid of the Mist docks, emanated from the Niagara Falls Waste Water Treatment plant on Buffalo Avenue, according to the water board's Executive Director Rolfe Porter, who said it was the result of some work being done to maintain one of its sediment tanks.

"Part of the process requires us to back wash our filters,” Porter told 2 On Your Side. “Our filters are carbon filters so they're black. When we back wash those filters, our back wash water is black."

“It was careless and unacceptable," said Pat Proctor of Rainbow Air, whose helicopters fly thousands of tourists over Niagara Falls every summer, and who captured dramatic images of what appeared to be a giant black cloud in the water.

Proctor also serves as the Chairman of the Niagara Falls Tourism Advisory Board.

“It’s a hiccup that we hope just doesn't happen again," Proctor said.

Unfortunately, a hiccup involving Niagara Falls is often heard around the world, and indeed Proctor confirmed he has had inquiries from media outlets around the globe seeking more information and permission to use his photos.

"We've had news outlets from over in Europe calling us, including the BBC, the UK Daily News, and the Associated Press as well,” Proctor said.

John Percy, who heads the Niagara Tourism and Convention Corporation, expressed his disappointment with the timing of the discharge to Channel 2 News.

"This should not have taken place on a Saturday afternoon at the height of the tourism season," Percy said.

Ordinarily it wouldn't have, according to Porter.

“Typically we do this type of thing in the spring and fall," he said.

However, he said that in this case there were specialized contractors expected to arrive at the wastewater treatment plant on Monday to repair the sediment tank in question, and that the tank had to be drained in order to allow that work to proceed.

“We had to do it for construction reasons,” Porter insisted.

Beyond the ill-fated timing of the discharge creating an unsightly spectacle for thousands of tourists, Proctor expressed dismay that there was no warning from the water Board that the discharge was about to occur.

“In the future, we’d hope that they would contact the city administration, just to give them a heads up to say that they have to do this, and that they would try and delay it until at least after sundown so that its visual impact would be diminished,” Proctor said.

“That certainly could have been an option,” countered Porter. “But that just didn't work out for us in terms of getting ready for the work crews on Monday.”

O'Callaghan vowed that improvements in communication will be a part of the review of the incident.