Coastal Maine includes 30 major estuarine systems. These are listed along 

 with their areal extent (where available) as determined by the FWS National 

 Wetlands Inventory (NWl) in table 5-1. The major estuarine systems comprise 

 more than 92% (120,111 acres; 48,628 ha) of the total estuarine system in 

 coastal Maine (130,075 acres; 52,662 ha). Twenty-three of these major systems 

 are >1000 acres (405 ha) in size; four are >10,000 acres (4049 ha) in size. 

 The locations of the major estuarine systems and their limits 

 (riverine/estuarine upper limit and marine/estuarine lower limit), as 

 determined by the NWl, are illustrated in figures 5-1 to 5-6. The locations 

 of specific areas are given in atlas map 1. The estuarine system is located 

 between a relatively small riverine system and a much larger marine system. 

 Since the three systems are contiguous, processes occurring in one area are 

 likely to affect the others. 



The estuarine system in Maine includes areas with considerable freshwater 

 inflow (e.g., Kennebec-Androscoggin, and Penobscot estuaries) and areas with 

 relatively little freshwater inflow (e.g., Somes Sound, Little Kennebec Bay, 

 and New Meadows Rivers). Specific estuaries in Maine are often contiguous 

 (e.g., Kennebec-Sheepscot , and Machias-East Machias) and receive freshwater 

 flow from more than one riverine source. 



Only the Sheepscot, Damariscotta , and Penobscot estuaries and the 

 Passamaquoddy/Cobscook Bay system have been the subject of detailed 

 hydrographic studies. Hydrographic data from these studies are examined under 

 "Hydrography" in this chapter. Little sampling of hydrographic data is 

 available for other estuaries. However, freshwater flow data on 11 rivers in 

 the characterization area are available from United States Geological Survey 

 (USGS). Using these data, tidal range data from the National Ocean Survey and 

 topographic data from nautical charts, a semiquantitative model is employed to 

 describe the hydrographic features of those 11 estuaries (Ketchum 1951). 

 Limitations of the model are discussed under "Hydrography." The hydrography 

 of the remaining estuaries is not discussed here because of the lack of data. 



The estuarine system in coastal Maine as discussed here consists of subsystems 

 and classes that have been identified by the NWl. The area exposed at low 

 tide (intertidal subsystem) is ecologically different from the area that is 

 submerged at all times (subtidal subsystem); for this reason, the two habitats 

 are discussed separately here. Estuarine classes identified by the NWl 

 include aquatic beds, unconsolidated bottoms, open water and rocky bottoms in 

 the estuarine subtidal subsystem and aquatic beds, beach/bars, flats, reefs, 

 rocky shores, emergent wetland, and streambeds in the estuarine intertidal 

 subsystem (figure 5-7). 



Intertidal and subtidal aquatic beds are principally eelgrass on mud 

 sediments. Unconsolidated bottoms are comprised of cobble, gravel, sand, and 

 mud. Vegetation may include eelgrass or emergent wetland species. Rocky 

 bottoms consist of substrata of bedrock and/or boulder. Vegetation is 

 principally algal beds (kelp). Beach/bar habitats encompass cobble, gravel, 

 and sand beaches. Flats include both sand and mud flats and streambeds 

 crossing the flats. Reefs are composed of mussels and usually are found on 

 mud flats. Atlas map 1 depicts the location of all estuarine systems, 

 subsystems and classes identified by the NWl in coastal Maine. 



5-3 



10-80 



