Prior to settlement, the river had an abundance of fish and was an important food source for local Indigenous peoples.
During colonial times, the river was dammed multiple times, including in the same place as the current Ellsworth Dam. Many of these were sawmill-style dams with fishways to allow for fish passage. The fish populations remained robust despite impacts from these dams.
In 1907 the Ellsworth Dam was built to generate hydropower. With the arrival of electrification, this dam was a game changer. Power from the dam electrified Blue Hill, Mount Desert Island, and powered the Brewer trolley cars. It was an economic boon and–as the tallest dam in New England–a marvel of modern construction. Despite spirited discussions, no fishway was built into the dam.
In 1924 the Graham Lake Dam was built. Shortly after it was built, the dam broke and resulted in the largest human-made disaster in the state’s history. Floodwaters from the dam failure wiped out many sawmills and other structures in Ellsworth. Shortly after this, an engineer named Graham rebuilt the dam that still operates today.
With the dam’s completion, Graham Lake filled existing marshland and flooded forest at the lake’s edge. During the Great Depression, people looking for free lumber cut down these flooded and dead trees from the frozen lake, leaving many stumps that still make Graham Lake difficult to navigate today. This incident led to new regulation requiring tree removal before any dam construction.
In the 1970s & 80s increased awareness and concern around the environment led to new understanding and regulations that affected the operations of the Union River dams. The owner of the dams, Bangor Hydro, successfully avoided investing in some improvements, like fish passage, through successful court cases.
In 1973 the Green Lake National Fish Hatchery, one of two in the country for Atlantic Salmon, opened. The hatchery’s operations at one time involved catching salmon at the Ellsworth Dam and bringing them to the hatchery to spawn. While this is no longer the case, the hatchery continues to grow young salmon that are stocked in rivers in Maine. Once safe fish passage occurs at the dams in the Union River, this hatchery will supply salmon for the Union River as well.
Modern updates to the Clean Water Act and Endangered Species Act, and the addition of the Atlantic salmon to the latter, now affect considerations for dam relicensing in Maine.
In 2013, Brookfield Renewable - a property manager - acquired ownership and operation of the Ellsworth Dam and a number of other dams in Maine as an investment opportunity for their shareholders. The dams are currently undergoing relicensing, which will require Brookfield to make major updates to the dams’ structural integrity, water quality, and fish movement. Brookfield appealed these requirements and was required by the State Supreme Court to reapply for a water quality certificate from the State of Maine.
A renewed national investment in green energy, including hydropower, has resulted in monies allocated to supporting and improving dams that are licensed to generate power. It is yet to be seen if the Ellsworth dams would qualify for such investment.