NEW YORK - Four waterfalls built as an art spectacle on Manhattan's East River are the subject of an eco-uproar for the damage their brackish mist is doing to the waterfront greenery.

Some New Yorkers want the $15.5 million falls created by Danish artist Olafur Eliasson to be shut off after Labor Day, not on Oct. 13 as scheduled, to spare the vegetation on the city's Brooklyn Promenade.

“We have lost shrubs, trees and plenty of plants on the promenade,” said Judy Stanton, president of the Brooklyn Heights Association. “They have been ... irreversibly damaged by the salt coming from the waterfall.”

The falls were erected at two locations off Brooklyn, including at the base of the Brooklyn Bridge; north of the Manhattan Bridge on the Manhattan side of the river; and off Governors Island in New York Harbor.

Parks Department First Deputy Commissioner Liam Kavanaugh acknowledges that vegetation along the Brooklyn waterfront and on Governors Island is “clearly showing signs of stress.” Salty water harms trees by interfering with the photosynthesis process needed to sustain life.

Kavanaugh said there should be no long-term damage since Parks Department workers are watering the plants regularly.

He said experts have recommended soaking the trees' root area once a week to flush out any salt in the soil, as well as hosing down the leaves and foliage in the early morning.

Among the critics are Michael “Buzzy” O'Keeffe, owner of the River Cafe restaurant by the bridge. He said leaves on the trees in the restaurant's sprawling garden are turning brown.

“They look awful now - like on a cold February day,” said O'Keeffe. “They can take a little salt, but not too much without dying.”

O'Keeffe estimated his damages at “hundreds of thousands” of dollars and said he plans to submit a bill to officials responsible for the project.

“Innovative art is a gamble, and this was not a win,” he added. “No art should be allowed to destroy things.”

The falls that were turned on in late June are New York's biggest public art project since The Gates in Central Park in 2005.

The money to build the falls was raised by the Public Art Fund, a private, not-for-profit organization. Individuals, foundations and corporations - including Mayor Michael Bloomberg's media company, Bloomberg LP - donated $13.5 million, and a state agency picked up the rest of the tab.

Bloomberg has said the project is expected to generate more than $55 million in economic activity for New York, money spent by visitors on everything from hotels, restaurants and stores to boat excursions to see the manmade cataracts. Officials had no estimate of how much revenue has been produced so far; The Gates were believed to be responsible for pumping $254 million into the local economy.

Besides browning vegetation, Eliasson's artwork has also been a hurdle to humans on the East River, with boaters getting caught in the current that sends them floating toward the roaring water.

Last month, harbor patrol vessels rescued two kayakers who got too close to the Brooklyn Bridge waterfall and were hanging onto pilings near the installation.

The waterfalls are on every day from 7 a.m. to 10 p.m., and illuminated after sunset.

AP-ES-08-29-08 1456EDT