An empty Mid-City lot that used to collect trash is now a park designed to collect thousands of gallons of stormwater, improving drainage in one of New Orleans’ most flood-prone neighborhoods.

The nearly 4-acre park at the corner of Toulouse and Moss streets, about a stone’s throw from Bayou St. John, can hold nearly 56,000 gallons of stormwater, the equivalent of 1,100 bathtubs, and ease pressure on the city’s drains and aging pump system.

“This was an abused piece of property that people would park on, and they’d trash it,” said Ghassan Korban, executive director of the Sewerage & Water Board, which owns the property. “We’ve made it an amenity.”

On the surface, the Bayou St. John Green Infrastructure Project looks like a grassy field with a scattering of newly planted cypress and oak trees. But short berms channel rainwater into a low spot ringed by a 150-foot-long retention wall that doubles as a seating area. The landscape is designed to hold water while porous pavement, special soils and tree roots soak and filter it. A large drain raised above the ground will handle overflow before water spills into neighboring properties, Korban said.

Mid-City is often referred to as the bottom of the “bowl” in the city’s concave topography. When it rains, water from a large area of the city drains into the neighborhood, flooding vehicles and sometime homes and businesses.

The park, which cost $270,000 to develop, is the 10th green infrastructure project the S&WB has completed to meet the requirements of a federal consent decree related to pollution from the city’s sewer system. In 1998, environmental regulators ordered the city to rebuild much of its East Bank sewer system to stop it from releasing untreated sewage into Lake Pontchartrain and other waterways.

As part of the consent decree, the S&WB agreed to invest $2.5 million on stormwater projects and educational initiatives. The park is the largest of the 10 projects, which include rain-absorbing gardens, porous pavement and green roofs at schools and other public properties.

The S&WB plans to build several more dual-purpose projects that serve as public spaces on dry days and temporarily collect and store runoff during heavy rains.

“This nature-based solution is a must as we add layers of protection for our city,” Korban said. “We need many projects like this.”

Over the next three years, water will be tested at various spots at the park to determine which which elements of the green infrastructure do the best job of cleaning runoff, which is often tainted with motor oil and other vehicle-related contaminants. The S&WB will incorporate those lessons into future projects.

“We’ll know if the area we planted the cypress or where we planted irises removes different pollutants,” said Dana Brown, a landscape architect who helped design the park. “It’s exciting. We’re going to learn something from this.”