Over the weekend, visitors to Niagara Falls were shocked and a little frightened when they saw the water at the base of the American Falls suddenly turn black.

According to Buffalo News.com, the water below the American observation deck all of a sudden turned dark as a slimy-looking black 'sludge' came flowing into the water.

The 'sludge' it turns out came from the Niagara Falls Wastewater Treatment Plant's routine maintenance.

Here's a short video showing what the water looked like over the weekend as the discharge flowed into the Niagara River:

The Niagara Falls Water Board released a statement concerning the incident:

The substance discharged is a result of the routine maintenance of one of the water board’s wastewater sedimentation basins located at the Waste Water Treatment Plant on Buffalo Avenue.

The “inky water” is the result of a routine, necessary, and short term change in the waste water treatment process. We apologize for causing alarm to residents, tourists and others. The blackish water contained some accumulated solids and carbon residue within permitted limits and did not include any organic type oils or solvents. The unfortunate odor would be limited to the normal sewer water discharge smell.

You can read the full statement at NFWB.org.

Although the Niagara Falls Water board had the proper sewer discharge paperwork to release the volume of sewage and sediment into the river, Governor Andrew Cuomo wasn't happy, Tweeting this:

Despite the proper paperwork, it seems like doing such a thing on a busy Saturday in the height of the summer tourist season seems like a lapse in judgement, 'routine' or not.