Rain Barrel Burden

Sept. 29, 2016
Rain barrels provide breeding ground for mosquitoes

About the author: Kelly Middleton is director of community affairs for the Greater Los Angeles County Vector Control District. Middleton can be reached at [email protected].

Thousands of residents of Los Angeles County, Calif., are requesting rain barrels for water conservation during the state's historic drought. SWS Associate Editor Bob Crossen spoke with Kelly Middleton, director of community affairs for the Greater Los Angeles County Vector Control District, about the rise in rain barrel popularity and how to mitigate risks associated with standing water.

Bob Crossen: What risks are associated with residential capture and detention of rain water?

Kelly Middleton: Unfortunately for Southern California, capturing rainwater for residential reuse has only limited benefits. Since we get most of our rain during the winter months, little, if any, rain falls to refill rain barrels during the hot summer months when water is needed most. One unfortunate design feature of many rain barrels is the spigot location several inches from the bottom of the barrel. This allows a few inches of water to remain in the bottom of the barrel, which can provide habitat for larval mosquitoes for months unless the barrel is turned over and emptied completely. One bucket or rain barrel can produce more than a thousand mosquitoes each week if left undisturbed, which can spread throughout an entire neighborhood.

Crossen: Why are storm water catchment systems (detention ponds, rain barrels, drains, etc.) attractive to mosquitoes?

Middleton: Preferred egg-laying habitat will differ between species; however, they all require a ready food supply in the water (algae and bacteria), calm or still water, and ideally, a lack of predators. Most storm water catchment systems have the potential to provide these needs: nutrient- and pollutant-rich urban runoff in a reliable, long-lasting and protected structure. Routine maintenance required to reduce these attractants, however, is often lacking.  

Crossen: What is the risk of Zika virus in storm water management systems?

Middleton: A new and rather concerning challenge for California’s vector control professionals are several invasive Aedes mosquitoes (Aedes aegypti, the yellow fever mosquito, and Aedes albopictus, the Asian tiger mosquito) that have recently been detected in many counties across the state. These mosquitoes are vectors (transmitters) of the viruses that cause dengue, yellow fever, chikungunya and now Zika. These mosquitoes thrive in urban environments and prefer to lay their drought-resistant eggs in small, man-made containers, both above and below ground, including [in] storm water management [systems]. Eggs can remain dry and viable for years awaiting the next influx of water before they hatch.

Crossen: How are storm water management programs addressing these issues?

Middleton: Thanks to the dedicated work of California Department of Public Health and vector control professionals, an increasing number of storm water management plans across the state have added language addressing mosquito production concerns. It is important for storm water program managers to have conversations with their local vector control agencies, [which] can help address problems in their communities.    

About the Author

Kelly Middleton