Rivers
Maine’s rivers connect forests, lakes, communities, industries, and the coast—and preserve visible traces of the state’s transportation and manufacturing history.
River systems across Maine
Water is one of Maine’s defining natural resources. Rivers gather runoff from land and lakes, form watersheds, support wildlife, and carry freshwater toward estuaries and the Atlantic.
Drainage area describes the land and water surface that contributes flow to a river. Comparing a river’s length with its drainage area helps show both the distance it travels and the scale of the landscape it collects water from.
From log drives to free-flowing channels
During Maine’s river drives, pulp logs traveled downstream toward mills. Many sank before reaching their destinations, while bark and wood accumulated beneath the water and continued to decay. Remnants may appear in tidal reaches when water levels are low.
Rock-filled cribworks anchored floating booms that steered logs around coves and obstructions. Dams also supplied power and regulated flow for mills and riverbank industries. The final log drive ended in 1976.
A major change came on July 1, 1999, when the Edwards Dam was breached and the Kennebec flowed freely through Augusta for the first time in 162 years. In winter, icebreaking helps keep major navigable channels open for marine traffic.
Maine’s twenty longest rivers
Lengths and drainage areas are presented as reference values. Parenthetical notes indicate the branch or outlet included in the listed length.
| River | Length (miles) | Drainage (sq. mi.) |
|---|---|---|
| St. John (with southwest branch) | 331 | 8,765 |
| Penobscot (with west and north branches) | 240 | 7,760 |
| Androscoggin | 174 | 3,430 |
| Kennebec (with west outlet) | 170 | 5,900 |
| Saco | 121 | 1,680 |
| Aroostook | 100 | 2,290 |
| Mattawamkeag (with west branch) | 83 | 1,520 |
| Dead River (with south branch) | 74 | 878 |
| Sebasticook | 72 | 890 |
| Allagash | 69 | 1,240 |
| Piscataquis (with south branch) | 67 | 1,500 |
| Sandy | 65 | 644 |
| Moose | 65 | 735 |
| Fish | 62 | 975 |
| Sheepscot (with west branch) | 55 | 228 |
| Narraguagus (with east branch) | 48 | 214 |
| Baskahegan* | 48 | 270 |
| Magalloway (with west branch) | 48 | 455 |
| Little Androscoggin | 47 | 350 |
| Machias | 46 | 450 |
*Baskahegan is described as an Indigenous word meaning “branch stream which turns down.” See the Glossary for terminology used throughout the collection.
Canals, locks, and connected waters
Engineered passages extended the usefulness of some Maine waterways by helping boats move between waters at different levels.
What this entry includes
Use the river list as a starting point, then follow linked entries for places, waterways, and recreation routes.
Watershed scale
Drainage figures show how much surrounding land and water contributes flow to each river system.
Industrial traces
Cribworks, submerged wood, dams, and former mill sites reveal how waterways were adapted for work.
Connected places
River entries lead into communities, wilderness waterways, canoe routes, and related ecological subjects.
Understanding Maine rivers
Quick explanations of the measurements, history, and terminology used on this page.
What does a river’s drainage area mean?
It is the total land and water area from which precipitation and runoff flow toward that river. It may include tributaries, lakes, wetlands, and smaller streams.
Why are branches included in some river lengths?
A named branch or outlet may form part of the measured river system. The table identifies those cases in parentheses so the basis of the listed length is clear.
How did river booms and cribworks function?
Floating booms guided logs through channels and around places where they could collect. Rock-filled cribworks anchored those booms and some remain visible today.
When did Maine’s last log drive end?
The state’s final log drive ended in 1976, closing a long period in which rivers served as major transportation corridors for timber.
Why was the removal of Edwards Dam significant?
Its breach on July 1, 1999 restored free flow through Augusta after 162 years and marked a major change in the Kennebec River’s modern history.
Where can I explore more river-related topics?
Follow the linked river names in the table or browse the broader Rivers ecology category.