KENNEBEC RIVER BASIN PHYSICAL DESCRIPTION OF THE KENNEBEC RIVER AND WATERSHED The Kennebec River basin, located in west central Maine, has a total drainage area of 5,893 square miles, constituting almost one-fifth the total area of the State of Maine. The Androscoggin River basin lies to the west, the Penobscot River basin to the north and east, and a section of the Maine coastal area to the south. The northwesterly limit of the basin forms a part of the international boundary between the United States and Canada. The basin has a length in the north-south direction of 149 miles and a width of 72 miles. The upper two-thirds of the basin, generally above Waterville, is hilly and mountainous, being part of the Appalachian Mountain Range. The lower third of the basin, including the Sebasticook River and Cobbosseecontee Stream tributary areas, has a more gentle topography representative of the coastal area. The Kennebec River Basin lies in a large section of Somerset County, the eastern part of Franklin County, most of Kennebec County, and smaller portions of Penobscot, Waldo, Sagadahoc, and Androscoggin Counties.3 A map of the Kennebec basin including hydropower sites is shown on page 35.
The Kennebec River originates at the outlet of Moosehead Lake and flows southerly 145 miles to the head of Merrymeeting Bay at Abagadassett Point, about seven miles above Bath. From Merrymeeting Bay the Kennebec waters continue south, through the Maine coastal area, another 20 miles to the Atlantic Ocean at Hunniwell Point. The main river is tidal as far as Augusta, 25 miles above Abagadassett Point. Between its origin and mean tide at Augusta, the river falls about 1,026 feet in a distance of 120 miles, as average gradient of 8.5 feet per mile. One "S" curve in the river, between Madison and Skowhegan, forms the only large digression in the river's southward course.
The principal headwater tributary is the Moose River which drains 716 square miles of mountainous watershed area easterly to Moosehead Lake. The tributary area of the Moose River represents about 58 percent of the total Moosehead Lake watershed (1,268 square miles). The Moosehead Lake watershed, in turn, represents about one-fifth (20 percent) of the total Kennebec basin area.
Principal downstream tributaries (draining at least 400 square miles) are the Dead, Carrabassett, Sandy, and Sebasticook Rivers. Individual drainage areas are listed in Table 3. The combined drainage area of the four principal downstream tributaries are about 2,800 square miles, representing 47 percent of the total basin area and about 60 percent of the area below Moosehead Lake.