THE BUZZ ON MOSQUITO CONTROL FOR STORMWATER DESIGN

With the appearance of West Nile Virus, stormwater projects are now viewed as potential public health threats. Designers find themselves not only considering mosquito control but also convincing clients that these methods will succeed. Depending on the species, there are three possible design strategies to discourage mosquito breeding: (1) Ensure that systems designed to empty following a storm do so within 72 hours; (2) Encourage a robust predator population in areas that remain wet, and limit the spread of emergent vegetation by establishing permanent deep-water zones of at least four to six feet; and (3) Animate the water surface with a spray, wave or flow motion, especially where permanent deep-water zones are not possible. Stormwater projects must be regularly monitored and maintained and be designed with access points that facilitate this care. Common failures involve excessive growth and decay of emergent vegetation, which can overwhelm predator populations and clog conveyance and aeration features; accumulation of silt, trash and other debris, which can create small pools of standing water; and mechanical or electrical malfunctions that can entirely shut down a system. More: “Managing Mosquitoes in Stormwater Treatment Devices”: http://www.anrcatalog.ucdavis.edu/pdf/8125.pdf; “Managing Mosquitoes in Surface-Flow Constructed Treatment Wetlands”: http://www.anrcatalog.ucdavis.edu/pdf/8117.pdf  Landscape Architecture, Nov 04, p 52, by Patty Gambarini.