Loads of East River seaweed pose challenge for plan to put floating pool on waterway

During the fall, heaps of seaweed repeatedly clogged a filter system designed for a future floating pool in the East River. Despite the setback, the project’s backers, who have been working on the idea for more than a decade, said they remain confident that aquatic plant life won’t derail their plans.

The vision for the so-called +POOL aims to build a series of platforms on the tidal estuary and use high-powered filters to clean its polluted water to make it safe for swimming. The concept was first pitched as a fundraiser via Kickstarter in 2013, but gained traction in January when Gov. Kathy Hochul and Mayor Eric Adams announced plans to fund the project.

The +POOL team said a small test version of the pool is expected to open next summer. They set up a barge on the East River to begin testing their filter system earlier this year. And this month, they wrote in an email about the challenges posed by the waterway’s seaweed.

“One thing we didn’t quite expect was how much seaweed would be pulled into our pre-filter, which required regular manual cleaning; and how much seaweed would grow in our mock up pool,” the email said. “Since we didn’t have swimmers in our mockup pool, we did not schedule regular cleanings and allowed algae to grow so we could assess cleaning frequencies for the full scale section we are building for next summer.”

The project’s backers said they’re working to address the seaweed problem, but noted their filters successfully eliminated harmful bacteria like E. coli to levels so low they weren’t detectable in lab testing.

“Even getting this temporary test in the river was pretty incredible to see,” said +POOL Managing Director Kara Meyer. “I think there’s an appetite for innovation in New York City and trying something that is going to return New Yorkers to their waters.”

The filter system didn’t use any chlorine, and instead relied on ultraviolet light to sterilize the water pulled from the river.

The +POOL team also contracted a company that sent underwater drones to the floor of the East River to see what was at the bottom as part of their environmental assessment. The drone captured video of the murky riverbed and the contractor said they saw black sea bass, red beard sponges, blue crabs and some algae species.

Meyer said that if New York City were to face an extended drought r similar to the one this fall, floating pools like +POOL could replace traditional pools that draw from the same reservoirs as the city’s drinking water.

“This is pretty unprecedented that we have this drought,” she said. “If these kinds of conditions continue, public pools are probably going to be the first on the chopping block.”

There’s still no firm date for the launch of the smaller version of the pool than the 9,000 square-foot concept announced by the governor and the mayor in January.

“It takes a long time to build things in New York City. Everyone always told us that and we know that,” Meyer said.