Casco Bay

Casco Bay: A National Treasure

Casco BayCasco Bay is an estuary, a fertile crescent of ocean where rivers and tides converge. Most of our country’s population centers were built along estuaries. These cradles of colonization, such as Boston Harbor, Long Island Sound, Chesapeake Bay, and Casco Bay, offered early settlers food from the sea, salt marsh hay for grazing livestock, and waterways for exploring the interior.

The rivers that fed the estuaries were tapped for drinking water, hydropower, and sewage disposal. Such use and abuse left some estuaries dead zones. Thanks to the watchful advocacy of many guardians, Casco Bay survives, although not as it was in Colonial days.

Casco BAYKEEPER® Joe Payne notes, “Unlike some other estuaries, Casco Bay isn’t dead or dying, but it is suffering from a lot of cuts. Our problems are manageable- we can work on them; we can even see the results; we can win. It is vitally important that all the friends of Casco Bay continue their activities towards improving the health of the Bay.”

Our estuary is saltier than most (a characteristic apparently preferred by lobsters) and cleaner than the rest, a quality enjoyed by all who spend time on Casco Bay. The Bay supports some 850 species of marine life; from microscopic plants to migrating pilot whales. Each spring, fifty islands become noisy nesting colonies for many of the 150 species of waterbirds that inhabit Casco Bay. Casco Bay is both a working waterfront and a port of call for cruise ships, oil tankers, and bulk cargo transports and a scenic postcard of historic forts, stalwart lighthouses, and secluded anchorages.

Casco Bay has not always been so picturesque. Beginning in the mid-1800s, tanneries, foundries, slaughterhouses, and shipyards amassed along the waterfront. Over the years, power plants, filling stations, tank farms, and sewage outfalls were added to the shoreline. Though many of these pollution sources have been removed, polluted runoff, combined sewer overflows, boat sewage, and the threat of oil spills still jeopardize the health of the Bay.


A Minute for the Bay

“In the 50 plus years I have known Casco Bay two remarkable changes have occurred. One is the unbelievable increase in the bird population. When I was a boy seeing an osprey was a once in a decade experience, a heron occasionally, an eagle – never. Now all are daily visitors. Eider ducks are everywhere, and terns and cormorants and laughing gulls…. The other is the increase in the number of people living next to the bay. Although a challenge to the bay as an ecosystem this development also multiplies the number of those with a stake in seeing the bay continue improving. I’m optimistic. Well done Friends of Casco Bay!”

-Chuck Hillier


“Last night, I climbed down to the edge of Casco Bay where earlier in the evening I had a wonderful swim. Much to my surprise the tide had receded leaving behind the gemlike intertidal pools that my flashlight illumined. As I looked out for the water’s edge, it seemed to go on and on and down, I saw boulders, green crabs, the dull yellow-brown seaweeds, but could not find the water so far had the tide receded! Then I became amazed to see the geological formations laid bare, absolutely fascinating. Now I must study more.”

-Peter Wolf


Have you had a compelling experience on, in, or around Casco Bay? What is your most recent or memorable experience that made you feel connected to Casco Bay? Please use our contact form to share your experience with us.


Winter on Casco Bay

Click the image to read more about winters on Casco Bay.

Click the image to read more about winters on Casco Bay.


An Estuary of “National Significance”


Casco Bay is one of 28 estuaries in the nation that has been designated an “Estuary of National Significance” by the U.S. Environmental Protection Agency. The EPA established the National Estuary Program in 1987 to protect nationally significant estuaries threatened by pollution, development, or overuse. In 1990, Casco Bay was inducted into the program, and the Casco Bay Estuary Partnership was created to develop a plan to preserve the ecological integrity of Casco Bay and ensure compatible human uses of the Bay’s resources through public stewardship and effective management.

The Casco Bay Estuary Partnership (CBEP) is one of Friends of Casco Bay’s primary partners. Besides providing us with on-going, significant support for our Water Quality Monitoring and Vessel Pumpout Programs, we partner on various projects such as lobster relocation, sediment sampling, and clam flat restoration. The Casco Bay Estuary Partnership also works with many other partners throughout the Casco Bay watershed as you will see when you visit the CBEP’s website.


Where In the World Is Casco Bay?

Casco Bay is located in southern Maine. It extends from Cape Elizabeth to Cape Small, encompassing 13 coastal towns, including two of the largest cities in Maine, Portland and South Portland. The Casco Bay watershed collects water from 42 communities and 958 square miles from Bethel to the coast.

Casco Bay