A Changing Casco Bay: The Bay Where You Work and Play Is at Risk
Learn How You Can Help Protect the Health of Casco Bay
For a full version of the report A Changing Casco Bay in PDF, please use this link: https://drive.google.com/file/d/0B_dTKz-k7OLmQzRlWGxFaXhwNGM/view?usp=sharing
Valued for its rich diversity of marine life, Casco Bay was designated an Estuary of National Significance by the federal government in 1990. A technical report from the National Oceanic and Atmospheric Administration on environmental benchmarks found that Casco Bay had twice as many marine organisms as other temperate bays. Since 1989, Friends of Casco Bay has been working to improve and protect the environmental health of Casco Bay.
The dots indicate work that Friends of Casco Bay volunteers and staff have done around the Bay over the past 25 years. Click on the image to see a larger version.
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Casco Bay by the Numbers
236,483 = Number of residents living in the Casco Bay watershed, from Bethel to the Bay (2010)
1 in 5 = Number of Mainers living in the Casco Bay watershed
578 = Miles of shoreline around the Bay
200 = Approximate area of water in the Bay in square miles
785 = Islands and exposed ledges in the Bay
$628,143,000 = Value of ocean related activities on and around Casco Bay (2011)
Working Waterfront and Scenic Postcard
Casco Bay extends from Two Lights in Cape Elizabeth to Cape Small in Phippsburg, encompassing 13 coastal communities, including two of Maine’s largest cities, Portland and South Portland, and two of Maine’s newest towns, Long Island and Chebeague Island. The Casco Bay watershed collects water across a landscape of nearly 1,000 square miles, from 42 communities between Bethel and the coast.
Casco Bay is an estuary, where rivers and tides converge. Rivers add nutrients, tides deliver cold, oxygen-rich seawater, and relatively shallow depths provide protected habitat. These factors make our estuary the feeding, breeding, and nursery grounds for 850 species of marine life in Casco Bay, from microscopic plants to migrating pilot whales, and for 150 kinds of waterbirds that nest here.
The circulation of water around Casco Bay is affected by runoff from rivers and streams, tidal action, currents, winds, and geography. Many small rivers, including the Fore, Presumpscot, Harraseeket, Royal, and Cousins, empty directly into Casco Bay, but their collective volume cannot match the influence of the Kennebec River. Even though it is not in the Casco Bay watershed, we have detected runoff from the Kennebec at Halfway Rock, nearly nine nautical miles from where the river enters the ocean.
Casco Bay is both a working waterfront—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.
In the mid-1800s, tanneries, foundries, slaughterhouses, and shipyards crowded the Casco Bay waterfront. Later, power plants, filling stations, tank farms, and discharge pipes from industry and sewage treatment plants were added to the shoreline. Though many of these pollution sources have been removed, polluted runoff, overflows from sewage pipes en route to sewage treatment plants, boater sewage, the threat of oil spills, and the effects of climate change jeopardize the health of the Bay.
For over 23 years, staff and volunteers have been collecting data for Friends of Casco Bay, to give us a better understanding of the health of our coastal waters. This report focuses on nitrogen, oxygen, water clarity, pH, and pesticides, to create a comprehensive overview of the water quality of the Bay.
Read next section of the report What’s Beneath the Beautiful View?