NIAGARA FALLS, NY – We are learning more about the sewage discharge which occurred near the base of the world famous Niagara Falls last Saturday.

Two On Your Side has obtained a copy of an internal memo sent early this week by an official with the Niagara Falls Water Board.

Its authenticity has been confirmed by two members of the water board as well as a manager at the agency, on the condition that they remain anonymous.

The memo provides, among other things, a timeline of events, and reveals that the discharge wasn't originally supposed to occur when it did....and certainly not how it did.

According to the memo, one of five sediment basins at the Waste Water Treatment Plant on Buffalo Avenue was in need of repairs to its baffle system.

To do this, the large rectangular pool of sewage must first be drained of its contents to allow contractors to access it. The memo indicates this process was to begin on Thursday July 27, but that staff shortages and mechanical malfunctions delayed the job until Saturday morning..

According to a source familiar with how the process works, when the basin is drained, enough clean water is supposed to be mixed in to dilute the remaining waste and carbon filtration sediment, so that it's no longer dark enough - or smelly enough-- to be noticeable when it's eventually pumped into the river, under a permit issued by the New York State Department of Environmental Conservation (DEC).

Due to staff shortages, according to the memo, the job was left largely in the hands of two operator/trainees who had been given careful instruction on the procedure by a supervisor.

Sources say the investigation is now centered on whether it was a valve malfunction, or an error by a worker to leave a pump on too long, that lead to the incident turning a portion of the lower river below the Falls black, before thousands of visitors at the height of the tourist season.

The contents of the memo seem to fall in line with the limited amount of information provided late Thursday, when Water Board Chairman Dan O'Callaghan appeared at a hastily called news conference.

Reading carefully from a prepared statement, O'Callaghan said, "it is clear to us that as a result of a possible human error or a possible mechanical malfunction, a large quantity of water from the sediment tank was released and that wasn't supposed to happen."

O'Callaghan declined to answer further questions, including when we attempted to ask him if the staff on duty at the time of the incident had been sufficiently trained.

According to several sources, O'Callaghan's declining to answer questions had much to do with the lawyers who flanked him at the news conference, and then who cued him to stop talking before hustling him away from reporters. Sources say Water Board attorneys have advised O'Callaghan and other officials to be guarded in what they say about all of this.

"I can't answer questions because this is currently being investigated," O'Callaghan said.

The incident has prompted a full scale investigation by the DEC into not only the discharge, but the operation of the city’s wastewater treatment plant, which is run by the Water Board.

Sources tell us the DEC was once again meeting with Water Board officials today.