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35th Anniversary logo for Friends of Casco Bay

The Casco Bay Watershed

A map of the Casco Bay watershed from the Casco Bay Estuary Partnership.

A watershed is an area of land that drains rainwater, snowmelt, and any other sources of water through a system of streams and rivers to a low point such as a lake, bay, or sea. Watersheds come in many sizes depending on geography and the specific receiving body of water. For example, the watershed for a small pond may encompass only a few acres, while the watershed for the Gulf of Maine includes much of the New England Coast and extends up into Canada.

In the Casco Bay watershed, the Bay is downstream from everything. The boundaries of the watershed include parts of more than 41 towns, cities, and the hundreds of Calendar Islands whose lands slope downhill and ultimately drain to Casco Bay. While the Casco Bay watershed comprises only 3% of land in Maine, it is home to one in five Mainers. Whether we find ourselves on shores of the Bay or as far inland as Bethel, Maine, our actions and those of our communities can impact the health of Casco Bay.