The use of synthetic Nitrogen fertilizers has increased steadily in the last 50 years. Synthetic fertilizers are commonly applied to agricultural fields as well as residential and commercial lawns. Nitrogen is a necessary nutrient for plant growth, however, overuse of fertilizers causes the excess to runoff into nearby streams
and rivers that lead to the Bay.

Urban nonpoint sources account for approximately one-fourth of the phosphorus and one-eighth of the Nitrogen reaching the Bay. With increased development of urban areas, these loads continue to escalate. Often, as homeowners treat their lawns, they over-fertilize, and mistakenly leave fertilizer on driveways and sidewalks, which allows the product to be washed directly into storm drains.
(The Chesapeake Bay Program, www.chesapeakebay.net)