Second, nearly a quarter of the nitrogen entering the Chesapeake comes from the air, and about half of that is from automobiles. Those automobiles are concentrated in the developing areas of the watershed close to the Bay, where they do the most damage. Even though we have made great progress as a nation in reducing the pollution produced from individual autos, urban sprawl has meant that the number of vehicle miles traveled in the Chesapeake region has gone up at a rate four times greater than population growth. So even as our cars have become cleaner, our development patterns have caused us to drive more and more, and to generate more nitrogen pollution. Finally, large lot subdivisions scatter over the landscape in ways that exacerbate nutrient pollution.
Lawns use much more fertilizer and pesticides per acre than the forests and farmlands they replace.
The roads and driveways that serve the subdivisions, and even rooftops, are all impervious and cause rainwater to wash off, turning creeks into flashing storm drains. In short, the land and the streams lose their ability to absorb the shocks and thus pass them on to the Bay. For all these effects, we have reason to celebrate the public's discovery of the costs of sprawl. And so long as it keeps up, the Bay will be a beneficiary. Bill Matuszeski is director of the EPA's Chesapeake Bay Program Office.