When it rains, water runs off hard surfaces like roofs, roads and sidewalks. Most of the water that falls on typical grass lawns turns into runoff, too. In New York City, stormwater runoff goes into the same combined wastewater system as sewage from homes and businesses. During many storms, so much water enters the system that the wastewater treatment plants are overwhelmed, and millions of gallons of stormwater and raw sewage are released into the area’s waterways.

The Queens Botanical Garden is trying to manage all of the rainwater that falls on our site to help prevent this kind of pollution. One of our most important tools are bioswales. These are low-lying areas that have been selected or excavated and planted with vegetation that can tolerate wet and dry conditions. Some of the plant species in the Garden’s bioswales include Sweet Flag Acorus calamus and Shallow Sedge Carex lurida.

When it rains, water runs off surrounding areas into a bioswale. There, the water is retained in the soil (a special soil mixture can be used to maximize retention), evaporated, absorbed by plants, and allowed to infiltrate back into the water table.

At the Garden, three bioswales has been completed as part of the Sustainable Landscapes and Buildings project. They manage excess rainwater runoff from the new buildings and paved areas. All of the stormwater that falls on the parking surface of the new Parking Garden will be managed by bioswales.

During a massive storm in November 2005, the Garden’s first bioswale successfully managed over a foot of rainfall over the course of a week!

Top right: Newly planted bioswale at Visitor & Administration Center in Fall 2007

Bottom right: Visitor & Administration Center bioswale as seen from roof in Summer 2008.

Image credits: Nicole De Feo