NIAGARA FALLS, N.Y. — Photos and videos surfaced on social media showing a pool of black water in the Niagara River.

Maid of the Mist tweeted out a video taken by Rainbow Air that shows the dark, sludgy-looking water.

Niagara Falls Water Board Executive Director Rolfe Porter released the following statement on the water.

"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.

NFWB remains committed to the highest quality of waste water treatment and the treatment and distribution of drinking water consistent with public health laws and regulations, the public enjoyment of natural resources, the protection of fish and wildlife and the economic development of the city of Niagara Falls, NY."

That water has returned to normal Sunday as shown in a picture below, courtesy of Rainbow Air.

The Niagara Falls Mayor Paul Dyster and City Administrator Nick Melson could not be reached for comment.