Yokum Brook in Becket, MA. Credit: USFWS

Dams Over Time

More than two hundred years ago, the first dam was built across the Connecticut River. Soon afterwards, Atlantic salmon became extinct in the watershed. Now there are more than 1,000 dams in the basin. See Dams Over Time, an animated map series of the increase in dams since 1850. The animation opens in a new window and is 515 KB in size, so it will take about 3 minutes the first time it is loaded (at 28,800 bps). It will then run in 10 seconds by using your browser's "reload" button.

Although dams have made it difficult to restore salmon, they have not made it impossible. The first map below shows the potential range of migratory fish if there were no upstream fish passage facilities, such as fish ladders. The second map shows that more than 1,000 miles of historic habitat has been made available to migratory fish by installing upstream fish passage facilities at selected dams (orange dots).

Map showing potential range of migratory fish if there were no fish passage facilities. Credit: USFWS

Map showing potential range of migratory fish after installation of upstream fish passage facilities. Credit: USFWS

Many thanks to Muhammad Irfan Azam of Pakistan for programming the animation sequence.