To see a map of the ponds and watersheds of Mount Desert Island, Maine, click on Pond Map.

Acadia National Park and Mount Desert Island are famous for their granite coastal hills, but between those hills lie valleys with streams and ponds equally deserving of fame.

Ponds are stream- or spring-fed lowlands or valleys where the watertable (the level of water held in the soil) rises above the surface of the soil to form a body of relatively still water open to the air. In some places the word "pond" is reserved for shallow bodies of surface water and "lake" is used for deeper ones, but in Maine all surface waters are considered to be ponded and are referred to as ponds.

Just because water in ponds moves more slowly than it does in streams doesn't mean there's nothing happening in ponds. Changes in daily and seasonal temperatures of water near the surface of a pond sets up currents of flowing water within the pond itself, promoting a corresponding flow of nutrients. In both spring and fall, pond waters turn upside-down, bottom waters rising to the top, surface waters sinking to the bottom. The fall overturn is the result of falling temperatures that leave surface waters cooler than the depths, causing the warmer water on the bottom to rise to the top. In spring, equinoctial winds (winds near the equinox) stir up the surface waters of a pond, establishing currents that drive a second annual overturn.

Ponds are often full of plant and animal life, especially if their waters contain nitrogen (needed for plant growth) and phosphorus (needed for plant reproduction). Aquatic plants grow at various depths, some preferring the shallows near the edge of a pond, some thriving in moderate depths. Many freefloating plants and algae benefit from the bright sunlight at the surface and the waterborne nutrients in the pond itself. Two examples of shallow ponds in Acadia National Park are the Tarn (in the valley between Dorr Mountain and Huguenot Head south of Bar Harbor) and Aunt Betty's Pond (north of Sargent Mountain). These two ponds are fast filling in with vegetation such as arrowhead, pond lily, and bayonnet grass and will be wetlands, not ponds at all, in the near future.

Acadia's deeper ponds have such clear water and low nutrient levels that they are relatively free of plant life. Eagle Lake is one such pond and is the water supply for the town of Bar Harbor, as Jordan Pond is for Seal Harbor, and Long Pond is for Southwest Harbor. Pond clarity is measured by dropping a weighted target (Secchi disk) overboard from a boat and lowering it until it can no longer be seen. Secchi depths for many of the ponds on Mount Desert Island are contained in the righthand column in the table of ponds below.

The Ponds of Acadia and Mount Desert Island (*=ponds wholly within the park)
POND	AREA	Max. DEPTH	Av. DEPTH	ELEVATION	TROPHIC	SAMPLE SECCHI DEPTHS
NAME	Acres	Meters	Meters	Feet	TYPE	Meters Low/High
Aunt Betty's Pond*	34	2.1	0.9	210	Eutrophic	1.7/2.1
Beaver Dam Pond*	8	4	4	215	Eutrophic
Bubble Pond*	32	11.9	6.4	331	Mesotrophic	6.0/13.5
Duck Pond*	1			170	Dystrophic
Eagle Lake*	437	34	13	274	Oligotrophic	7.5/14.1
Echo Lake	237	20.1	8.5	84	Oligotrophic	6.0/14.0
Fawn Pond*	3
Halfmoon Pond*	3	6.1	4.3	250	Mesotrophic	5.00
Hamilton Pond	41				Oligotrophic	0.8
Hodgdon Pond	35	6.7	3.4	50	Eutrophic	3.0/7.1
Jordan Pond*	187	45.7	25.6	274	Oligotrophic	9.0/18.6
Little Long Pond	38	1.5	0.9	20	Mesotrophic
Little Round Pond	16	5.2	2.4	70	Mesotrophic
Lake Wood*	14.8	3.4	2.1	136	Mesotrophic	2.9/3.4
Long Pond (Isle au Haut)	73	18	7	15	Mesotrophic	8.1
Long Pond (MDI)	897	34.5	11.3	59	Oligotrophic	5.0/12.9
Lower Breakneck Pond*	8	6.4	3.4	260	Mesotrophic	3.8
Lower Hadlock Pond*	32	12.2	5.5	188	Mesotrophic	6.7/9.5
Round Pond*	38	5.8	3.4	72	Mesotrophic	4.0/5.5
Sargent Mt. Pond*	1	3	3	1,070	Oligotrophic	3.3
Seal Cove Pond	283	13.4	5.5	38	Mesotrophic	4.5/10.2
Seawall Pond*	5
Somes Pond	104	7.6	3.4	38	Mesotrophic	3.0/5.9
The Bowl*	6	9		410
The Tarn*	8	1.2	0.9	97	Eutrophic	0.7/1.1
Upper Breakneck Pond*	9	3.7	1.8	260	Eutrophic	3.6/3.8
Upper Hadlock Pond*	35	11.3	4.3	228	Mesotrophic	5.0/7.8
Witch Hole Pond*	28	9.5	3.7	179	Mesotrophic	2.9/5.3

Only two ponds on Mount Desert Island are acidic, Sargent Mountain Pond and Duck Pond, which are about one acre in size with a pH of 5.0 or less. The acidity of Sargent Mountain Pond is thought to be caused by atmospheric deposition on a small, granitic watershed with little soil; the acidity of Duck Pond results from its being fed by a naturally acidic wetland.

POND TROPHIC TYPES
• OLIGOTROPHIC--Ponds lacking plant nutrients and plants, with high levels of dissolved oxygen (Eagle Lake and Jordan Pond)
• MESOTROPHIC--Ponds with moderate levels of nutrients, plants, and dissolved oxygen (Bubble Pond and Upper Hadlock Pond)
• EUTROPHIC--Ponds with abundant plant nutrients, algal blooms, with low levels of dissolved oxygen (The Tarn and Aunt Betty's Pond)
• DYSTROPHIC--Acidic ponds with high levels of vegetable matter from a small variety of plants (Duck Pond)

The following table contains readings that show variations with depth of water temperature and dissolved oxygen content in Eagle Lake on September 23, 1998. At a depth between 19 and 20 meters, the temperature abruptly falls several degrees and the dissolved oxygen drops and then trails off. Cooler waters and decaying organic matter on the bottom markedly decrease the amount of oxygen available to living organisms. Those bottom nutrients are carried upward at the spring and fall overturns, making food available to organisms in the upper levels where dissolved oxygen is more plentiful. Generally speaking, in ponds what goes down must come up.

EAGLE LAKE; DEPTH/TEMP/DO 9/23/98
DEPTH	TEMPERATURE	DISSOLVED OXYGEN
Meters	Centrigade	PARTS/MILLION
00	17.2	8.8
01	17.2	8.8
02	17.2	8.8
03	17.2	8.9
04	17.2	8.7
05	17.2	8.9
06	17.2	8.8
07	17.2	8.7
08	17.2	8.7
09	17.2	8.8
10	17.2	8.8
11	17.2	8.7
12	17.2	8.8
13	17.2	8.8
14	17.2	8.7
15	17.2	8.8
16	17.2	8.9
17	17.2	8.9
18	17.1	8.8
19	17.0	8.5
20	13.8	3.6
21	13.3	3.3
22	13.1	2.9
23	13.0	2.6
24	13.0	2.5
25	13.0	2.4
26	13.0	2.3
27	13.0	2.1
28	13.0	2.1
28.5	13.0	0.3

Learn more about Acadia's water resource program.