Everybody was surfing — surfing M-T-A.

Wednesday night’s downpours took out a temporary wall at the Court Square-23rd Street subway stop in Long Island City, flooding the platform and knocking a man off his feet and nearly onto the track as a train entered the station, according to video posted on the @SubwayCreatures Instagram account.

“It’s nuts. It was the craziest thing I’ve ever seen. It was up to your shins,” said Luke Power, a Manhattan man who witnessed the deluge and helped the unidentified flood victim.

“I jumped over and grabbed the guy’s hand and helped him up. I’m not sure he spoke English – he was very disoriented.”

Power said that he could see the flooding was getting bad as he entered the station around 8:30 p.m.

“When I walked over to the overpass, there was all this water starting to come up at the mezzanine level,” he said. “I walked down [over to] the Manhattan platform. It was all starting to come out of that blue wall . . . The M train was coming.”

He added that the water smelled worse than normal rain water, as if a pipe had broken. “I had to throw out my shoes.”

Power later responded to an earlier MTA tweet about signal problems, saying “That’s not a signal problem it was a tidal wave.”

The MTA claimed the deluge was caused by a nearby construction site.

“This was an absolutely unacceptable and avoidable incident caused by a contractor working on a residential development project that could have put lives at risk,” MTA spokesman Shams Tarek said.

“Our initial investigation finds that severe and dangerous flooding was caused at the Court Square subway station last night when a private developer building a residential tower adjacent to the subway station – as well as a new entrance and elevator for the station – allowed their construction site to become inundated with water after their contractor relocated utilities and did not have the proper pumping system in place to act as a temporary drainage system.”

The MTA would not publicly identify the contractor, but said it is “taking steps to make sure the developer and contractor are held accountable and this doesn’t happen again.”

Signs posted in the subway say that contractor John Civetta & Sons is building the station entrance. The contractor did not respond to a request for comment.

Straphangers at the subway station Thursday were floored by the footage.

“It doesn’t seem safe. I’ve always thought they should have a barrier up. I mean, the MTA’s always been terrible. It’s just so old. You go to other places, they have a barrier between the trains, so God forbid if a flood comes nobody’s hurt,” said Raphaella Baek, 27.