What is a Watershed?

Every body of water has a watershed—an area of land that drains water into some kind of basin. The watershed is named after the basin: Swan Lake. Belfast Bay. Penobscot Bay.

Size & Impact
They can be huge--the Penobscot Bay Watershed has a drainage area of more than 8,500 square miles--and they’re foundational to local wildlife, human life, and the economy. To quote Gaylord Nelson, senator and founder of Earth Day: “The economy is a wholly owned subsidiary of the environment, not the other way around.” That’s demonstrably true in Mid-coast Maine, where we depend on fisheries, farming, and tourism, as well as clean drinking water, for survival.

Nationwide more than $450 billion in goods and tourism depend on healthy watersheds. Learn more from EPA’s watershed page >

How a watershed works (or doesn’t)

Of course, around here, we tend to think of water flowing toward the bays and the ocean. But that’s not the whole story.

When rain fails or snow melts, it can soak into the ground, where it might linger in the soil and seep to the nearest stream—or drain deeper down into an aquifer. Or the water may slough off along hard surfaces (such as marine clay on the Maine coast or manufactured surfaces in a city) and flow toward the lowest point available.

Oftentimes these low points are literal “storm drains,” which are sometimes overwhelmed.

Oftentimes they’re rivers, which can also be overwhelmed—think Hurricane Helene’s impact in North Carolina. All of these dynamics affect the quality of our freshwater—and the ocean. NOAA has a lot to say about this.

What is a healthy watershed?

EPA can get pretty technical about the health of watersheds—but give it a visit.

At the Watershed Coalition, we’ve got our eye on

Habitat. Is the watershed healthy enough to support natural habitat? This means, in part, free-flowing streams for fish, as well as forests and fields that can host diverse species—including the birds and bugs that make our world bloom. Learn more about our educational programs, designed for grownups and kids.
Water quality. Can our water support healthy biological communities? For instance: Can it support lobsters, kelp, and other saltwater species? Does it support land-based plants that we all need? Can we humans count on safe drinking water? (One of our efforts: We monitor Belfast Bay >)