by Tom Lalley
Most of us are just finishing up the arduous task of raking and bagging leaves around our properties. We rake leaves for many reasons like aesthetics, safety and to keep our lawns healthy, but there’s another reason to rake leaves that you may not have considered: the health of Chesapeake Bay and other local waterways.
Every year, leaves from urban areas flush into sewers and waterways causing phosphorus and nitrogen levels to spike. Both elements are essential to plant life but too much of them in water kill aquatic animals and plants. Even without leaves, the city’s waters would be polluted and unsafe for human contact.
The biggest offender is runoff from the city’s streets, but a new study from the U.S. Geological Survey found that leaves can account for 56 percent of the annual load of phosphorus in storm water. When leaves are cleared from streets, the percent drops to just 16. The study was conducted in Madison, Wisconsin, but the researchers say that the results are applicable to any urban area with a phosphorus pollution problem.
During the fall, the city’s Department of Public Works collects leaves twice a month. On top of reducing pollution from leaf litter, DC also composts its leaves and provides the resulting mulch free of charge to city residents.