As if it didn’t already have enough, the East River seems to attract water: Last summer, its big draw was a floating swimming pool; this summer, it will be waterfalls — created by an artist.

Olafur Eliasson, a Danish–Icelandic artist whose installation “The Weather Project” drew 2 million people to the Tate Modern in 2003 and 2004, has designed what will likely be the city’s biggest public art project since Christo and Jeanne-Claude’s “The Gates”: a series of freestanding waterfalls in the East River.

Mayor Bloomberg and the Public Art Fund, a private nonprofit organization that produced, among other works, Anish Kapoor’s “Sky Mirror” and Jeff Koons’s “Puppy,” both at Rockefeller Center, are scheduled to announce Mr. Eliasson’s project at the South Street Seaport tomorrow.

According to a source whom the mayor told about the project, the waterfalls will rise about 60 to 70 feet above the water — more than half as high as the roadway of the Brooklyn Bridge. They will be visible from the area around the Seaport, from Brooklyn Heights, and from the Governors Island Ferry.

Someone who was briefed on the waterfalls project last year said that, at that time, it was estimated to cost between $9 million and $11 million.

The waterfalls project will coincide with a retrospective of Mr. Eliasson’s work, called “Take Your Time,” which will run at the Museum of Modern Art and P.S.1 between April 20 and June 30. The exhibition, currently at the San Francisco Museum of Modern Art, is the first major retrospective of his work in America.

Mr. Eliasson is known for creating immersive environments that take their inspiration from nature and play tricks with viewers’ perceptions. With “The Weather Project,” Mr. Eliasson used mist, mirrors, and 200 monofilament light bulbs to create an image of a glowing sun in the Tate Modern’s Turbine Hall. In a work called “Green River,” in 2000, he poured nontoxic dye into a river in Stockholm, turning it green. In an early work called “Beauty” (1993), he created a rainbow in a gallery by projecting light across a fine mist of water.

Born in Copenhagen to Icelandic parents, Mr. Eliasson has long been interested in waterfalls, which form an important part of the landscape of Iceland. A piece called “Reversed Waterfall” (1998), which will be included in the P.S.1 exhibition, uses a system of pumps and basins to send water jetting uphill. In 2005, he created a 20-foot outdoor waterfall as part of an exhibition at Dundee University in Scotland.

Many of Mr. Eliasson’s works have a subtle environmental message. “The Weather Project” was partially intended to make viewers contemplate their personal experience of weather and climate. The exhibition at SFMOMA includes a work called “Your mobile expectations: BMW H2R project,” in which Mr. Eliasson removed the outer shell of a BMW hydrogen-powered race car and replaced it with a translucent surface of steel mesh, reflective steel panels, and ice. A 1999 series of photographs, called “The glacier series,” documented glaciers in various stages of melting.

Mr. Eliasson is one of a number of contemporary artists working on a scale that requires vast workspaces and fleets of assistants. According to a 2006 profile in the New Yorker, he has a 15,000-square-foot studio in a former train depot in East Berlin and employs about 40 people there, including mathematicians, technicians, lighting designers, and architects.

The New York City Economic Development Corp. estimated that Christo and Jeanne-Claude’s “The Gates,” a series of some 7,500 saffron-yellow gates that were installed in Central Park for 16 days in February 2005, attracted 1.5 million out-of-town visitors and generated $254 million in economic activity for the city. The project cost more than $20 million and was financed entirely by the artists.

A spokesman for the mayor declined to confirm plans for the waterfalls project.