A blog called Brand Avenue has an item about The Channels and at the end of it, they link to a webpage about proposed islands in another stream, the Mississippi River at St. Louis:

When the Great Rivers Greenway District called upon Balmori Associates to provide a proposal for the St. Louis riverfront master plan in October 2005, the firm initially developed four schemes for the underutilized three-quarter mile riverfront. Traditional plans of a pedestrian promenade in a landscaped park were discarded, however, for a more bold and atypical concept: a riverfront of floating islands....

The current proposal includes a series of islands suspended on catamaran-like supports and linked by floating walkways. The original proposal included detachable landforms, which would be flexible enough to change the shape and size of the islands. A major benefit of the proposal is not only this flexibility in landform configuration but also in the potential to change the riverfront’s seasonal activities. As [project manager Javier] Gonzalez explained, “You could detach one of the connecting pieces to attach a new one with a new function. In one you may have a kiosk in the summer, then you could take it to the shipyard and come back with another island with something for the winter.”

When I read the word "landforms" I keep thinking about Colorforms.

By the way, the reason the St. Louis riverfront is "underutilized" is because it was cleaned out by urban renewal.