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Perspectives on Casco Bay



8 miles of shoreline

200 square miles of water

8 official lighthouses and 8 historic forts

13 municipalities from Cape Elizabeth to Phippsburg, including Long Island and Chebeague Island, abut Casco Bay.

1 in 5 Mainers live in the 42 communities of the Casco Bay watershed, from Bethel to the Bay.

1989 Friends of Casco Bay was founded to improve and protect the environmental health of Casco Bay.

1990 Casco Bay was designated an Estuary of National Significance under the Clean Water Act.


With the arrival of spring, we hope you seize the Bay by getting outside to enjoy our 578 miles of shoreline, taking in that 200 square miles of water, and visiting those lighthouses and forts!

What’s in a name?

What’s in a name?  

Casco Bay has had many names.

Where did the name Casco come from?

The Abenakis called this place Aucocisco [ah-coh-sis-ko]. While some have translated Aucocisco as “Place of the Herons,” it more likely meant “marshy place” or “place of the slimy mud.”

European explorers may have shortened Aucocisco to Casco.

Others say that when Portuguese explorer Estêvão Gomes sailed into the Bay in 1525, he thought the Bay was shaped like a helmet, or casco in Spanish, and christened it Bahia de Casco, Bay of Helmet.

Colonel W. Romer made an inspection of Casco Bay for the British in 1700. He reported back to London, “Casco Bay had a multitude of islands, these being reported as many islands as there are days in the year.” Today, despite the fact that 785 islands and exposed ledges have been counted here in Casco Bay, the region is quaintly known as the Calendar Islands.

Did you know…How many lighthouses are in Casco Bay?

Did you know…How many lighthouses are in Casco Bay?
All are in the southwest region of the Bay, which is not surprising, since this where ship traffic is concentrated. Draw them on a chart of Casco Bay.
1. “Bug Light,” South Portland, Portland Breakwater
2. Spring Point Ledge, South Portland, Southern Maine Community College campus
3. Ram Island Ledge
4. Portland Head Light
5. Two Lights, Cape Elizabeth
6. Halfway Rock Lighthouse, south of Baily Island
7. Echo Point Light, Great Diamond Island (a tiny lighthouse on the southwest tip of the island)
8. Little Mark Island, south of Bailey Island (this light is on a monument and is not officially a lighthouse)


Become a pollution detective

Become a Pollution Detective!

What is polluted runoff? What are sources of pollution in stormwater runoff? (pesticides & fertilizers, pet wastes, litter, oil & road salt, soil & sand, leaky septic systems, motor oil)
On the next rainy day, grab your rain gear and boots, and investigate your own neighborhood for evidence of these actual or suspected sources of water pollution.


____ Dirty water flowing downhill into a stream, gully, or other water body


____ A worn, straight path that leads toward a gully, road, or stream


____ A storm drain that is blocked by leaves and other debris


____ Bare ground where soil can wash away in the rain


____ Oil stain on a driveway or road that indicates oil or gas dripping


____ Pet waste


____ Other evidence of stormwater pollution




So you think you know Casco Bay

So You Think You Know Casco Bay


1. What are the landward and seaward boundaries of Casco Bay?


_________________ _______________________

2. How many coastal or island communities border Casco Bay?



3. What is an estuary and why is it important?






4. What are some of the leading threats to the environmental health of Casco Bay?




5. Name two important marine residents of Casco Bay and describe why they are important.

______________________ ________________________________________


______________________ ________________________________________


6. Describe one action children and/or their families can take to protect Casco Bay.


ANSWERS: So You Think You Know Casco Bay

1 What are the landward and seaward boundaries of Casco Bay?
Cape Elizabeth (Two Lights), Cape Small (Phippsburg), Halfway Rock

2 How many coastal or island communities border Casco Bay? 14

3 What is an estuary and why is it important?
Where rivers and ocean meet; important as feeding, breeding, and nursery grounds for marine life and birds; protected, food-rich settlements for humans

4 What are some of the leading threats to the environmental health of Casco Bay?
Stormwater runoff, nitrogen pollution, sewage, coastal acidification

5 Name two important marine residents of Casco Bay and describe why you think they are important.
Lobsters most important fishery in Maine
Eelgrass nursery for many marine animals
Soft-shell clams 2rd most important fishery in Maine
Harbor seals iconic marine life
Mackerel, striped bass, bluefish popular among recreational fishermen
Pogies (menhaden) caught commercially for lobster bait

6 Describe one action your family can take to protect Casco Bay.
Reduce use of fertilizers and pesticides, don’t discard cigarette butts, pick up dog wastes, any other actions that reduce pollution that can run into the Bay


Field trip!
Go to Buoy Park, the small park next to the Casco Bay Lines terminal along Commercial Street in downtown Portland. You will find four panels that explain the history of Casco Bay. (If you can’t get there, read them here [http://www.cascobayestuary.org/resources/graphics-signs/)
Find three facts you did not know and create your own “So you think you know Casco Bay” to quiz your family and friends.


Stewardship: Design your perfect yard

BayScaping: Design Your Perfect Yard


Our idea of the “perfect yard” grew from our ancestors’ appreciation of the manicured lawns of English estates. On any issues related to estate you can also hire litigation lawyers as they an help you out legally. Moreover, large expanses of grass require heavy investments of fertilizers, pesticides, water, and labor. After Edwin Beard Budding invented the lawnmower in 1830, Americans became obsessed with lawns. By 1870, thanks to promotion by landscape architects, the detached home with a manicured lawn was the standard to which homeowners aspired. (New York Times, “A Thousand Years of House & Home,” December 30, 1999) Today, Americans spend about $7 billion a year on lawn care equipment and supplies.

By thinking about how we actually use our outdoor living space, families might design their yards to reflect how we really use them, and create a yard that requires less lawn, less maintenance, and is more environmental to boot.


Connecting lawn care with Casco Bay

Casco Bay is one of the primary reason people live in this region. Residents need to know that their lawn care practices can affect Casco Bay, even if they are not waterfront owners. Every time it rains water flows off roofs (Check out here to find the best roofing services along with its prices), streets, driveways, lawns, parking lots, and other surfaces, carrying pollutants. Water flows like a funnel down the watershed into the Bay. Runoff from yards enters groundwater and streams and eventually makes its way into the Bay, where it can promote algae growth that can deplete oxygen marine organisms need.


  1. Discuss, “What does grass need in order to grow”?

(i.e., Sun, Soil, Nutrients, Water, Warmth, Air (carbon dioxide and oxygen)


  1. What do children need for growth?

(i.e., Air (carbon dioxide and oxygen), Food, Water, Shelter, Clothing)


What requirements do plants and humans have in common?

What requirements for plant growth are supplied “automatically” by nature?

Which assistance/addition might need to be supplied by humans?


  1. Find photos of different kinds of yards. Photos of different kinds of yards, especially from different cultures, which can be found on the Internet or in Home & Garden magazines. Try to locate examples of English estates (our heritage), Japanese gardens, desert or xerotrophic yards, forested area, wildflower fields, rock gardens, paved playground, water garden, etc.

Discuss one highlight from each landscape. Highlight yards that minimize grass, as they require fewer chemicals to maintain them (fertilizers and pesticides); yards that have many trees or bushes, as these help to prevent stormwater runoff.


Ask children which landscapes they like best.

What features would they add to their own yard?


  1. Ask them to consider

How do you like to use your yard?

Who else would you like to use it? (wild animals, birds, insects, friends, pets, etc.)

How could you make your yard better for the environment? (don’t put down pesticides, prevent stormwater runoff, have buffer plantings to hold soil, cover bare ground with grass seed, less grass, etc.)


  1. Together, make a rough map of your own yard or a nearby plot of land, incorporating some or all of these features:
  • Unvegetated areas
    • Any buildings, structures, driveways, walkways or areas without lawn
  • Uses of your lawn
    • Sitting or barbecue area, play areas, sports areas, garden work area or compost bin, open turf for visual enjoyment
  • Non-turf vegetation
    • Garden beds, groundcovers, trees, shrubs
  • Light
    • Best areas for grass are generally where the lawn gets 6 or more hours of sun a day
  • Problem turf (grass) areas
    • Heavily worn, compacted, pest-damaged, or unused/excess lawn areas
    • Surface water runoff, gullies, or eroding soil
    • Soggy areas


  1. Ask children what features they would add/delete to make their yard more environmentally-friendly and more kid-friendly. Are they the same features?


  1. Have them re-draw their property depicting it with features that would make it their ideal yard.


  1. Brainstorm alternative uses for the family lawnmower if you had less lawn!



Read The Secret Garden by Frances Hodgson Burnett. Discuss how a special piece of land can be a refuge and an outlet for creativity.

Ecology: What makes Casco Bay an estuary?

Estuaries are defined as “where the river meets the sea”

Estuaries form where river meets the sea and fresh water mixes with salt. Teeming with life, these places of salt marshes, eelgrass beds, mudflats, and tidal waters serve as nursery areas for oceangoing fish, migratory stopovers for shorebirds, and homes for an amazing diversity of shellfish, fish, mammals, horseshoe crabs, crabs, plankton, and many others sea creatures.

Casco Bay is saltier than most estuaries because the rivers that flow into Casco Bay are small and do not contribute much fresh water to the system.

Salinity variations in Casco Bay are less a result of changing tides, as in many estuaries, than the distance from freshwater inputs (rivers and rain runoff)


Find the rivers of Casco Bay

Look at a map of the towns that border Casco Bay, from Cape Elizabeth to Phippsburg. [link] Find the rivers that flow into Casco Bay (Fore River, Presumpscot River, Royal River, and Harraseeket River).

Lay a string along the twists and turns of each river from its source to the sea, and then straighten it out on a ruler to find the length. Which is longest?

Which one is closest to where you live?

Look at a chart of Casco Bay.

Here’s a trick question: Which river delivers the most freshwater to Casco Bay?

The river that delivers the most freshwater to Casco Bay isn’t even in Casco Bay; it’s the Kennebec River, which flows into the ocean between Phippsburg and Georgetown, just beyond Casco Bay. It carries water from several rivers, including the Kennebec, Cathance, and Androscoggin rivers. All are considerably longer than any rivers that flow into Casco Bay. This freshwater input curls around and into eastern Casco Bay.


Fresh to Salty

Find 3 sites on the chart: a river mouth, a nearshore site, and offshore:

  • Mouth of the Presumpscot River, Falmouth
  • Fort Gorges, which is just off the Presumpscot and Fore rivers
  • Ram Island Ledge at the entrance Portland Harbor (not far from Portland head Light)


Which one do you think is the saltiest? Which one is the least saltiest?


A river has zero salinity; Casco Bay’s average salinity ranges from 25 to 32 parts per thousand (ppt), and open ocean water has salinity of about 32-35 ppt. Thus, the average salinity of seawater is about 0.3%.


Another way to figure out which site is saltiest is to look out the actual data collected by Friends of Casco Bay.


How did we collect this information? Volunteers collected water samples along the shoreline between April and October; staff scientists sampled by boat year-round.


Average Surface Salinities at 3 Sites in Casco Bay, 2001-2005

Measured in parts per thousand (ppt)

Compare the average monthly salinity data for those three sites in Casco Bay.


Month                  Presumpscot River                          Ft. Gorges           Ram Island Ledge


January                                                                                                29.4 ppt                                32.0 ppt

February                                                                              31.0                                        32.1

March                                                                                   27.8                                        30.7

April                       1.3 ppt                                                  28.7                                        30.0

May                       2.6                                                          30.0                                        30.6

June                      1.3                                                          28.0                                        30.3

July                        2.4                                                          29.9                                        30.6

August                  2.3                                                          30.1                                        31.2

September         4.2                                                          30.5                                        31.4

October               3.1                                                          29.5                                        31.7

November                                                                          29.5                                        31.3

December                                                                           28.1                                        32.9


What’s left behind?

What factors affect the salinity in Casco Bay? (rivers, tides, rain, melting snow, evaporation, ocean currents).

Collect jars of water from a river, from just where the river meets the bay, and from the ocean. Put each sample into a separate aluminum pan and allow the water to evaporate over the next day or two. What is the residue left at the bottom of pan?  How do they differ?

After all the water has evaporated, mix up the pie plates and challenge others to figure out which is from the river (hint: no salt, maybe a little sand), the mouth of the estuary (some salt), and open ocean (most salt).

Caution: Don’t let anyone try to figure out which is saltiest by tasting the granules! Why not?


Books that trace the river to the sea

  • The Secret Bay by Kimberly Ridley and Rebekah Raye, Tilbury House, 2015
    The Secret Bay uses a variety of formats to explain the life of estuaries:  poetry, natural-history sidebars, and field guide
  • A Day in the Salt Marsh. by Kevin Kurtz, Sylvan Dell Publishing, 2007
    Hourly changes brought on by the tides


What is the value of estuaries?

Brainstorm a list of ways that an estuary is valuable for wildlife (including marine life, birds, and terrestrial animals). If you need ideas, check out the resources below:

Geography: Navigate Casco Bay


Navigating Casco Bay


If you were planning a trip across Casco Bay, you would need to know the answers to the questions below before you ever set sail. Use the chart of Casco Bay to figure out the answers to these navigation questions. Pay attention to the scale and compass direction on the chart.


What town marks the eastern boundary of Casco Bay?



Which town marks the western boundary of Casco Bay?



How far apart are they (in a straight line: “as the crow flies”)?



Find Halfway Rock. How far is Halfway Rock from each of these communities?


Eastern_____________ Western_____________


If you were on a sailboat, in what direction would you sail to travel from the mouth of the Fore River to the tip of Harpswell?



What body of water is beyond Casco Bay? ____________________________


Name the four rivers that flow into Casco Bay. (You may find more, but only these contribute much fresh water to the Bay.)











BONUS: How far is it, approximately, from the tip of Harpswell Neck to Cape Small. (You can use the scale on this chart or a road map)


By car ______________

By boat _____________



Navigating Casco Bay ANSWERS


If you were planning a trip across Casco Bay, you would need to know the answers to the questions below before you ever set sail. Use the chart of Casco Bay to figure out the answers to these navigation questions. Pay attention to the scale and compass direction on the chart.


What town marks the eastern boundary of Casco Bay?


 Phippsburg (at Cape Small)



Which town marks the western boundary of Casco Bay?


Cape Elizabeth (at Two Lights)



How far apart are they in a straight line (“as the crow flies”)?


About 16 nautical miles by boat



Find Halfway Rock. How far is Halfway Rock from each of these communities?


Eastern 8 1/2 n.m. Western 7 nautical miles



If you were on a sailboat, in what direction would you sail to travel from the mouth of the Fore River to the tip of Harpswell?




What body of water is beyond Casco Bay? Gulf of Maine


Name the four rivers that flow into Casco Bay. (You may find more, but only these contribute much fresh water to the Bay.)

Fore River                   Royal River Presumpscot River          Harraseeket River


BONUS: How far is it, approximately, from the tip of Harpswell Neck to Cape Small. (You can use the scale on this chart or a road map)


By car   About 23 miles  By boat  About 8 mile


Geography: Where is Casco Bay in the world’s oceans?

Geography Lesson: Where is Casco Bay in the World’s Oceans?

Casco Bay is part of a larger ocean system called the Gulf of Maine, a semi-enclosed body of water within the Northwest Atlantic Ocean. Bounded by Nova Scotia, New Brunswick, Maine, New Hampshire, and Massachusetts, it forms what people call “New England’s Own Ocean.” Georges Bank and Browns Bank form its eastern rim, setting the Gulf of Maine apart from the rest of the Atlantic Ocean.  These relatively shallow waters have been rich fishing grounds for cod and other fish for over 400 years. The Gulf of Maine is slightly larger than the state of Maine.

Why the Gulf of Maine is good for fishing

If you have ever jumped into the ocean in Maine, you know it is COLD! Cold water holds more oxygen than warmer waters. Both animals and plants need oxygen to live.

Nutrients from land are carried by rivers into the Gulf of Maine, where they fertilize the cold waters and promote the growth of tiny plants, phytoplankton, the base of the ocean food chain.

Cod and their relatives, pollock, hake, and haddock, have firm, tasty flesh. This white fish is sought after by diners, and so the fish are sought after by fishermen. Many cold-water fish travel in giant schools, which makes it possible—and profitable—for fishermen to capture thousands of fish at a time. They drag huge nets along the ocean floor. When the fleeing fish become tired, they are swept into a smaller net at the back, appropriately called the “cod end.” They are described in Fishes of the Gulf of Maine at http://gma.org/fogm.

Where is the best fishing?

On a map of the world, locate these prime fishing grounds. What bioregions are they in? [cold water]

  • Georges Bank, off Massachusetts
  • Grand Banks, off Newfoundland
  • Southern Africa
  • North Sea
  • Iceland
  • Norway
  • Barents Sea
  • Bering Sea in the North Pacific
  • Gulf of Alaska
  • Coastal areas around Japan
  • Northeast Pacific


Many of the most popular food fish have declined by 80% or more from overfishing and habitat destruction. Find out more about the Sustainable Seafood movement at Seafood Watch, Sustainable Seafood:  www.seafoodwatch.org


Find the Gulf of Maine on a globe

The ocean has different climate regions, just like there are on land.

Look at a globe of the world. The bioregions of the world are defined by their distance from the imaginary line around the center of the earth, the Equator.


Latitude and longitude are the two grid coordinates by which one can locate any point on Earth. Lines of longitude run north and south. Greenwich, England, has been designated to be 0 o longitude. Locations are calculated E or W of this imaginary line. Portland is about 70oW longitude.

Latitude is measured in degrees North and South of the Equator. The Equator is at 0 o latitude. Our latitude in Maine is around 45oN.

Find these latitudes on the globe:

  • 5oS to 23.5oN: Tropical region
  • 5o to 66.5oN and S: Temperate regions
  • 5oN to 90oN and S (Arctic and Antarctic): Polar regions


Find Maine on a globe and follow the latitude line around the globe to see what other countries are on the same parallel of latitude. Do you think these countries have the same climate as we do? Do the same with the line of longitude. Do these have different climates? The distance from the Equator affects how warm and cool a region is, and ocean currents also warm and cool a region.

If you were a fish, where would you rather live?

If you were to ask people to picture where in the world oceans they would find the largest number of fishes, most would say the tropical seas, conjuring up images of a vivid, bustling coral reef. But consider the locations of the major fisheries of the world, which depend on netting huge quantities of fish in each tow; they are in cold waters. Temperate and cold seas are home to relatively few species of fishes, but many individuals, and while tropical waters offer a staggering variety of life, there are far fewer individuals of each species.

 “Country Fish”: The fishes of cold and temperate waters

The cold waters of temperate and frigid seas may look murky, but they aren’t polluted. It’s the rich sea soup of plankton that reduces visibility to a few feet under the water and makes it appear green above. Advantage: Abundant food


“City Fish”: Coral reef residents

Tropical seas are hugely popular with divers and underwater photographers because the water is so clear. That is because there is relatively little plankton floating in the water to obscure your view.

In comparison to colder waters, tropical seas are relatively empty, except for coral reefs. A coral reef is like a city in the desert—an oasis—which may provide the only food and shelter for many miles around. The animals there have evolved complex strategies to compete for the limited food and hiding places within the shelter of the coral reef.  Advantage: Many hiding places