After an inky, foul-smelling discharge blackened the water near the base of Niagara Falls during a busy tourist weekend, several U.S. lawmakers are calling for the resignation of the board that runs the wastewater treatment plant on the American side of the river. 

A preliminary report of the discharge, posted to an online database by the New York State Department of Environmental Conservation (NYSDEC), lists the cause of the spill as "equipment failure," CBC News has learned. 

The material discharged is listed in the report as "raw sewage" and a previous statement by the Niagara Falls Water Board clarified that the "inky water" was the result of residue from black carbon filters used to clean the water.

However, New York Governor Andrew Cuomo and several New York legislators suggest that "criminal charges" may be warranted from the "potentially serious" incident.

The water board for the city of Niagara Falls, N.Y. had originally said that Saturday's discharge was part of routine maintenance of one of its basins.

Cuomo said "the original version of, 'Well, we did this and this was pursuant to a (Department of Environmental Conservation) permit,' I don't believe is true." 

The NYSDEC said in a statement earlier this week that the discharge violated state water quality standards by changing the colour and odour of the Niagara River. The volume, extent and the impact of the spill remain unknown.

Several state legislators have asked for their attorney general, the district attorney and the Environmental Protection Agency to investigate. Niagara Falls MPP Wayne Gates has also called for an investigation in an open letter to provincial Environment Minister, Chris Ballard.

If found guilty of violating state water quality standards, the city could face a fine of up to $37,500. 

Mayor of Niagara Falls, Ont., calls for better communication

The mayor of Niagara Falls, Ont., said Cuomo's comments and the reaction to the spill led him to believe the incident was "suspect."

"I don't know if we're talking sabotage or deliberate, but doing a flush like this especially at this time of the peak season, it makes no sense at all," said Jim Diodati.

He said discharges happen in Canada too, especially in times of wet-weather events like heavy rainfall with flooding, to prevent sewage backing up into people's basements. But the fact that no protocol was followed in this instance, with regards to communication or notification, concerned him.

"When we do it... we have to notify the Ministry of Environment, we have to post it on our websites and let the public know so that they're aware of what we're doing and why," said Diodati. "But something like this... everybody was quite surprised."

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The water near the base of the falls that border the U.S. and Canada turned an alarming shade of black before tourists' eyes following a foul-smelling discharge from a wastewater treatment plant. (Patrick J. Proctor/Rainbow Air Inc./Associated Press)

The mayor said he first learned of the discharge on social media, where visitors had started sharing images and video of the black water spreading and tagged him. 

"The frustrating part was I didn't know what it was, I didn't know what had happened, I couldn't get any information," he said, adding he immediately reached out to the mayor Niagara Falls, N.Y., who also seemed to be unaware. 

In an open letter, Niagara MPP Gates called on the provincial ministry "to investigate this matter immediately and find out definitively what this black discharge was composed of, ensure that no damage was done to the Niagara River, and take steps to ensure that such an incident does not occur again." 

 The Ontario Ministry of Environment and Climate Change (MOECC) said that while it did not have direct involvement with the incident, it is in contact with the city of Niagara Falls, N.Y. and the Department of Environmental Conservation to request more information. 

According to a statement from spokesperson Lindsay Davidson, both theU.S. and Canadian Coast Guards have protocols in place to notify each other and the MOECC Spills Action Centre if there are any spills that occur in shared waters. However, she told CBC News that the discharge was not reported to the Spills Action Centre by any agency or member of the public.

Officials at Environment and Climate Change Canada have not yet provided comment.

Experts say discharge violated regulations

Ian Brindle, emeritus professor of chemistry at Brock University who has researched water contamination in the lakes for four decades, is skeptical about the official story, saying there's a lot more to hold the other side accountable for.

The Niagara Falls Water Board said the water "did not include any organic type oils or solvents," but Brindle says that does not dismiss the possibility that it could have contained heavy metals, bacterial contaminants, or "legacy" contaminants from historic industrial spills that could've made their way into the treatment plant. 

"The main question is what could have happened to people swimming in the area. If that amount of raw sewage has been dumped into the river, then the possibility of bacterial-borne diseases increases. There is an acute effect for people using the water recreationally, and it would have an effect in minutes," he said.

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The water board for the city originally said Saturday's discharge was part of routine maintenance of one of its basins, and that the discharge was within permitted limits. (Patrick J. Proctor/Rainbow Air Inc./Associated Press)

Brindle thinks Cuomo's comments stem from the fact that, before any discharge takes place, there is a regulatory framework in place to provide extensive information about the types of contaminants being treated, and what its potential effects could be — a protocol that was clearly not followed here. 

"There's been a significant lapse in responsibility somewhere here," he said. "They need to educate people. They can't just do this and then seek an apology after the fact. It's disgraceful."

Water board officials issue apology for causing alarm

The water board for the city of Niagara Falls, N.Y., said in a statement Sunday the discharge was part of routine maintenance of one of its basins, and its colour the result of "a routine, necessary, and short term change in the waste water treatment process." 

The board reassured people that the discharge was within permitted limits.​

Rolfe Porter, executive director of the board, did not respond to multiple calls. There were no immediate reports of fish kills, or changes in the quality of drinking water for towns downstream of the river—including Lewiston, N.Y., and Niagara-on-the-Lake, Ont..

With files from The Canadian Press