A 25ac (10ha) site in New Orleans is to be transformed by into an environmental, recreational and educational amenity that will use natural processes to store and treat excess stormwater.

Designed by Waggonner & Ball, Mirabeau Water Garden will provide a place for stormwater to drain to, be stored and be naturally filtered.

In addition to reducing the impact of potential flooding on streets and homes, it will be a recreational amenity, a space for community gatherings and a means of reducing the risk of soil subsidence in the area.

The site was owned by the Congregation of St. Joseph but was donated to the City of New Orleans on the condition that it be used to enhance and protect the neighbourhood.

The project, meanwhile, will be the first major piece of construction of the Greater New Orleans Urban Water Plan, which was conceived after Hurricane Katrina with the aim of implementing sustainable strategies for groundwater and stormwater management in New Orleans.

The water garden will be able to store and clean up to 24ac ft (29,600 cu m, 7.8 million gal) of stormwater diverted from the city’s drainage system in the event that it should be overwhelmed.

Spaces around the garden have been designed around each different phase in the stormwater management process, showing visitors and helping them to understand the processes that are taking place.

Native plants will be used throughout the site to absorb water and remove pollutants, while "bioswale" channels around its perimeter planted with native vegetation will provide another means of collection and filtration.

Planting will also be used to tell the story of the site's location and history, with evergreens used to contrast soft meadows, native meadow grasses providing cover and native grass and perennial wildflower species.

The intention is for the water garden to be used as a model for managing stormwater that can be used at other open spaces and institutional sites in New Orleans and the surrounding areas.