US Army Corps of Engineers
New England District

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Maine River Basins

There are 19 principal river basins that lie entirely or partially in New England. Eight river basins lie in Maine to include the Saint John, Penobscot, Saint Croix, Kennebec, Androscoggin, Presumpscot, Saco and Piscataqua. Three of these basins, the Saint John, Penobscot and Kennebec, have Corps' flood risk management projects within their drainage areas.

Saint John River Basin
The Saint John River Basin is one of the largest basins on the Atlantic Seaboard. It has a drainage area of 21,360 square miles, of which approximately 14,000 (66 percent) square miles lie in the Canadian provinces of New Brunswick and Quebec, and 7,360 square miles (34 percent) in northern Maine.

The basin has a maximum length of approximately 121 miles and a maximum width of approximately 253 miles. For about 100 miles, the Saint John River forms the United States-Canada boundary.

The Saint John River Basin occupies most of Aroostook County and small sections of Somerset, Piscataquis and Penobscot counties.

Penobscot River Basin
The Penobscot River Basin is New England’s second largest river basin lying entirely within the region, exceeded only by the Connecticut River Basin. Located completely within Main, the basin’s northwestern limit forms part of the international boundary between Maine and Quebec.

The basin has a maximum length of about 125 miles and a maximum width of about 115 miles.

The drainage area of the Penobscot River Basin is approximately 8,570 square miles. The basin occupies large sections of Piscataquis and Penobscot counties, and smaller parts of Somerset, Aroostook, Washington, Waldo and Hancock counties.

Kennebec River Basin
The Kennebec River Basin, located in west central Maine, has a maximum length of about 149 miles and a maximum width of about 72 miles. The northwestern limit of the basin forms part of the international boundary between Maine and Quebec.

The basin’s total area of approximately 5,910 square miles constitutes nearly one-fifth of the total area of Maine.

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 the Penobscot, Waldo, Sagadahoc and Androscoggin counties.

St. Croix River Basin
The St. Croix River Basin stretches across the international boundary, lying in the southeastern corner of Maine and the southwestern portion of New Brunswick, Canada.

It has a maximum length of about 70 miles and a maximum width of about 50 miles.

Of its total area of 1,635 square miles, 1,010 square miles (62 percent) lie in Maine, and 625 square miles (38 percent) lie in New Brunswick. In Main, most of the basin lies in Washington County, with smaller sections lying in Aroostook, Penobscot and Hancock counties.

Androscoggin River Basin
The Androscoggin River Basin, which lies partly in western Maine and partly in northeastern New Hampshire, begins at the Canadian border and stretches to the Atlantic Ocean.

It has a maximum length of 110 miles and a maximum length of 65 miles.

The basin consists of 3,450 square miles, with 2,730 square miles (79 percent) lying in Main and 720 square miles (19 percent) in New Hampshire. In Maine, it comprises nearly all of Oxford and Androscoggin counties and smaller portions of four other counties: Franklin, Cumberland, Kennebec and Sagadahoc.

Presumpscot River Basin
Located in southwestern Maine, the Presumpscot River Basin lies entirely within the state and has a total area of 920 square miles.

The basin’s maximum length is 63 miles and maximum width is 41 miles.

The basin occupies most of Cumberland County and minor portions of Oxford, Androscoggin and Sagadahoc counties.

Saco River Basin
The Saco River Basin stretches from eastern New Hampshire into southern Maine. It covers an area of 1,697 square miles, of which 870 square miles (51 percent) lie in New Hampshire and 827 square miles (49 percent) in Maine.

The basin has a length of nearly 75 miles and a maximum width of 44 miles.

In Maine, the basin occupies the southwestern section of Oxford County, most of the northern third of York County, and minor areas of western Cumberland County.

Piscataqua River Basin
Although it lies mostly in southeastern New Hampshire, a portion of the Piscataqua River Basin lies at the souther tip of Maine. Of the basin’s total area of 1,022 square miles, 776 square miles (76 percent) lie in New Hampshire and 246 square miles (24 percent) lie in Maine.

The Piscataqua River and its largest tributary, the Salmon Falls River, form the boundary between New Hampshire and Maine.

The Piscataqua River Basin has a maximum length of 48 miles and a maximum width of 35 miles. In Main, the basin occupies the southernmost portion of York County.

- Updated: 12 June 2015