Biotope & Bioswales

Cleansing Biotope

The Garden’s Cleansing Biotope, located at the western end of the Visitor & Administration Building, is an area planted with selected native wetland species such as Soft Rush (Juncus effusus) and Swordgrass (Scirpus americanus).

During a storm, rainwater runs off the roofs of the building and terrace and other impermeable surfaces into the Cleansing Biotope. The water filters through the plant root systems, where contaminants are removed and treated by bacterial activity on the root surface.


The cleansed water is stored in a 24,000-gallon underground cistern and eventually piped underground to the entry plaza fountain. After gurgling out of the fountain, the water flows across the plaza through a water channel planted with native vegetation. At the end of the plaza, the water channel turns and runs alongside the Visitor & Administration Building, bringing the water back to the Cleansing Biotope to begin the cycle again.

All of the water used in the fountain and water feature is provided in this way, conserving fresh water while reducing stress on New York City’s wastewater system.


Bioswales are another integral part of QBG’s stormwater management plan. These low-lying areas have been selected or excavated and planted with vegetation that can tolerate wet and dry conditions.

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 & 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 Parking Garden is also managed by bioswales.

Photo Credits: Jess Brey, H. David Stein