Friday night’s deadly collision of a small powerboat with a moored construction barge just south of the Tappan Zee Bridge was an accident waiting to happen

The crash killed bride-to-be Lindsay Stewart and best man Mark Lennon, both 30, and injured the groom and three others, including the boat’s driver, now accused of driving while intoxicated.

If so, he’d be far from the only drunk on these waters. Almost every evening, dozens of similar boats ply their way across the Hudson in a parade between Tarrytown, Piermont and Nyack.

Many have only one thing on their minds: getting a drink at the Washington Irving Boat Club in Tarrytown, which serves until last call at 11:30 p.m. on an outdoor patio next to its marina.

But preliminary construction work is underway around the marina, the start of the Thruway Authority’s five-year, multibillion-dollar project to build a new Tappan Zee Bridge.

And the boaters are barely mentioned in the hundreds of pages of the environmental-impact statement for the project; instead, it details the risks of noise and to auto traffic as well as to sturgeons and oysters.

Yes, it mentions “temporary disruptions” to boaters and marinas, but claims the “work zone would be clearly marked . . . to alert boaters of potential navigation hazards” so they “would not be adversely affected.” It recognizes the Boat Club — under “Visual and Aesthetic Resources.”

Huge work platforms by the shores are detailed on project materials, but no stationary barges are mentioned. Soon there will be 60.

The 1,600-plus pages of agreements with the contractor, Tappan Zee Constructors never mention boaters or barges.

Plopped randomly in the river, these barges are hundreds of yards north and south of the bridge. There are no flashing warning lights or buoys, no “icicle” lights dangling from their sides, chains of LEDs or coned-off areas.

Lighting rules for moored barges also don’t cut it when dozens of boaters, jet skiers, sailboats, kayaks and work boats are crisscrossing the bay.

Along with deck lights, the Coast Guard requires just four white lights on a barge’s corners, to be visible for one nautical mile. No lights are needed on the mooring itself — a big floating “box” anchored in the river — or the rope to the barge.

It’s now clear those rules aren’t enough.

A friend recalled a drunken night ferrying a group to the Boat Club when he noticed a tug line and barely avoided a catastrophe. He gave his boat away.

From our house by the river, the barges are hard to see in daylight; at night they vanish. After the accident, the contractors added “some” lights; we still couldn’t see them. On Monday, a crane barge by the bridge was awash with light, the others were still invisible.

The Coast Guard’s weekly “Active Public Notices” buried on its Web site, warns in longitudinal and latitudinal detail where sturgeon “telemetry receivers” are located but not the huge barges. Coast Guard spokesman Charles Rowe said the barges and locations aren’t detailed “because they move,” and may be relocated. They’ll also multiply like bunnies as work gets underway.

Along the Erie Canal, also controlled by the Thruway Authority, hazardous areas are clearly marked with dozens of orange and white buoys. So far, nothing like this warns off boaters from the Tappan Zee barges.

Rowe says the Coast Guard may now have to check boats at night by the Boat Club. But the contractors and the state also have a responsibility here.

“We have a community-outreach group and are working on an ongoing basis to remind boaters that this is an active construction zone,” said a Thruway official. “We urge and continue to urge the public to stay clear of the construction zone for their own safety.”

To stay clear, however, you have to be able to see the obstacles. The contractors should quickly plan and get approved strings of lights and water safety buoys to create a bright wide path around all the barges.

The new bridge is one of Gov. Cuomo’s core initiatives — meant to show that New York, under his leadership, can still get big projects done. Under pressure, it seems his underlings overlooked a few safety steps.

And now Lindsay Stewart and Mark Lennon are dead. The Thruway Authority needs to crack down on safety now. No one else needs to die or be injured.

Lois Weiss writes The Post’s “Between the Bricks” and kayaks on the Hudson.