Initially marked for land reclamation, it was saved by a large coordinated effort by volunteers who submitted a report and petition to the government, expounding on its biodiversity and value to Singapore's nature conservation. It is now under the National Parks Board, who conducts guided tours (using volunteers) during low tide season to the general public. There is now a visitors centre, and even a boardwalk for people to get up close to the marine life.
For urban Singapore, this is an excellent venue for a nature family outing, and it is evident when I see many families joining the guided tour of the wetlands. Do note the tide timings and details on how to get there etc can be found on our NParks website. Enjoy!