Prior to the construction of manmade dams, migrating fish were able to ascend up the Hudson River to Glen Falls, nearly 200 miles from the Atlantic.
On the Mohawk River, the first major tributary to the Hudson, migrating fish could reach Cohoes Falls, a natural barrier approximately 3 miles upstream of where the rivers come together.
Under these natural conditions, the Albany, NY area was identified as important spawning grounds for alewife, blueback herring, shad, sturgeon, and other species of anadromous fish.
The Green Island Project (aka the “Federal Dam”) is located at river mile 152 on the Hudson River, 5 miles north of Albany, NY. The project is the first dam on the Hudson River and is the head of tide. Upstream of Green Island, 12 additional dams have the potential to restrict or block fish migrations.
In 2009, the resource agencies and the Green Island Power Authority, the license holder for the powerhouse on the Federal Dam, signed a settlement agreement to address fish passage at the complex.
Changes to the Federal Dam will include re-aligning the dam, installing a downstream fish passage screening system and expanding the powerhouse. Improvements to the powerhouse and the dam are expected to take place in 2013.
source: NOAA Fisheries