All of the water that falls on the ground will either be absorbed by plants or drain to the lowest point in the area, usually a lake or stream. We can map the high and low points of the terrain to create maps of when potential rainfall will flow and collect. This area, the drainage area, in combination with rainfall averages gives us an idea of how much water is flowing into a system. It also lets us know where the water is coming from and where potential pollutants may be going.
Watersheds area also defined by scale. For example, water from the LEA parking lot collects in a storm-drain that goes directly to Stevens Brook. Taking a step back we see that Stevens Brook flows into Long Lake. Oil leaking from a car in the parking lot would therefore affect Stevens Brook, but also Long Lake. On an even larger scale Long Lake flows through Brandy Pond, down the Songo River and into Sebago Lake, eventually through the Presumpscot River into Casco Bay. Use the map below to explore Maine’s watersheds. Scroll in and out to see watersheds at different scales and how they are all connected!