Talbot Mills Dam Removal

It is upstream of two dams on the Concord River:

1. The Middlesex Dam, which is breached so fish can pass here under normal flow conditions.
2. Centennial Island Dam which has a fish ladder for fish passage.  Fish counts are conducted here each year .

The Concord River is part of the Sudbury, Assbet and Concord River (SuAsCo) watershed. These rivers flow northward from the headwaters in Westborough to empty into the Merrimack River in Lowell.

The mill complex has many components.

The dam, made of granite-block, holds back the water…

and diverts some of the water behind the dam through two sluiceways.

The sluiceways direct water to two large mills, where it was used to generate power: Talbot Mills Complex on the south side of the river, and Faulkner Mills Complex on the north side of the river. These mills used water from behind the Talbot Mills Dam to power their operations until the mid to late 1800s, at which point they moved to steam power.

The sluice gate on the north side of the dam, which once controlled the flow of water into the Faulkner Mill, is still in place.

However, due to its poor condition, water currently flows through this gate uncontrolled.

Another gate controlled the flow of water into the Faulkner Mill. This gate is currently open and receiving uncontrolled flow from the gate upstream.

A waste gate, on the south side of the dam, which once controlled the flow downstream in the river, is now plugged.

A fishway on the north side of the dam plugged with a concrete block in the 1960's, and remains that way today.

Talbot Mills Dam was also used to divert river water into the Middlesex Canal, which connected Lowell to Boston.  The canal was used to move goods produced on the Merrimack River down to Boston between 1802 and the 1860s. Mules pulled barges across the Concord River on a floating towpath. 

Today, the Talbot Mills Dam no longer serves any industrial purpose, but still has an impact on the local ecology, hydrology, and recreational use. The dam holds back water, creating an impoundment known as the Mill Pond. The dam raises the water level significantly for approximately 0.5 miles upstream to the Pollard St. bridge. It has minor impacts on water levels upstream. The dam slows the flow of water, resulting in near-stagnant conditions upstream during dry summers. It also prevents the natural movement of sediment and nutrients downstream to the Merrimack River and estuary. It is a barrier to fish passage, restricting or preventing the movement of migratory fish both up and downstream.

The approximate limit of the Mill Pond is at the Fordway Bar at the Pollard St. bridge, a naturally-occurring stretch of bedrock, boulders, and heavy gravel which creates a high-point in the river. This bar was a natural place for people and wildlife to cross the Concord River before the Pollard St. bridge was built.

The Concord River is also used for many other purposes. Three miles upstream is the public drinking water intake for the town of Billerica.

The river is popular for recreational fishing, boating, and  birding. The Great Meadows National Wildlife Refuge is upstream on the Concord River, as is Minute Man National Historical Park. The federally-designated Wild and Scenic Sudbury, Assabet, and Concord River begins about five miles upstream of the dam. Twenty-nine miles of these rivers have special protection due to their exceptional scenic and recreational value. They are protected by the Wild and Scenic River Stewardship Council made up of local municipal, state, federal and non-profit representatives under the guidance of the National Park Service. This Partnership Wild and Scenic River is one of only 16 such rivers in the US–a unique and precious resource.

American eel (Anguila rostrata) are another ancient species, with Anguila species entering the fossil record 83 million years ago. American eel are unique as the only catadromous species in North America, meaning they spawn in the ocean, but live their adult lives in freshwater habitat. The lifecycle of eels has long been shrouded in mystery. They spawn in the Saragasso Sea, but this event has never been seen by human eyes.

Eels have long been a source of human food, many people today are familiar eating eel as unagi sushi, and there continues to be a commercial fishery in Maine. Unfortunately habitat fragmentation, pollution, and overharvesting have led to their decline. American Eels are listed as endangered by the  IUCN 3.1 .

To learn more about the American Eel, check out this PBS documentary The Mystery of Eels

Blueback Herring (Alosa aestivalis), Alewife (Alosa pseudoharengus) , and American Shad (Alosa sapidissima) all belong to the Alosa genus of river herring. Like sea lampreys, these three species are anadromous, spawning in freshwater and spending their adult lives in the ocean.

The Alosa genus first evolved 55 million years ago, and these species play a critical role in oceanic food webs. They are a prey species for many fish targeted by commercial and recreational fisheries, as well as being prey for mammals and birds, including four species of birds and three species of whales listed as endangered by the state of Massachusetts.

Shad, alewife, and blueback herring have also long been used by humans as food, bait and fertilizer. Their numbers have declined considerably from their historic levels, primarily due to habitat fragmentation caused by dams, with the  IUCN  considering blueback herring to be a vulnerable species.

To put into context how long these fish have been on the earth, human ancestors only split off from the ancestors of chimpanzees 6 million years ago and our species, Homo sapiens, has only existed for ~400,000 years.

Not only do these ancient species have unique evolutionary histories, due to their multi-habitat lifestyles, they play a critical role in nutrient cycling between oceanic and terrestrial ecosystems. They are at the base of the food chain, supporting many species in rivers and oceans. When their populations suffer, so do the many species that rely on them.

All of these species have an ancient history of human use as food, and have played an important role in human life in North America.

Human presence in the Concord River valley goes back to the end of the last Ice Age. As the glaciers retreated,  our current landscape emerged and the northeast gradually became habitable for humans and migratory fish alike.

Approximately 22,000 years ago New England and much of North America was buried under miles of ice.

Approximately 14,000-12,500 years ago the glaciers melted, leaving behind rivers and large glacial lakes including Glacial Lake Sudbury and Glacial Lake Concord.

The famed wetlands and sluggish pace of the Great Meadows are a result of the gradual upslope of these ancient lake bottoms.

Approximately 12,500-10,000 years ago humans first entered the region following the retreating ice. The SuAsCo and Shawsheen River watersheds contain a large inventory of known pre-contact Native American sites. Artifacts from these locations provide a glimpse into life long ago. Migratory fish began populating the area soon after glacial retreat as well.

The ecosystem at the time was cold tundra and grasslands. Human lifeways were migratory, following herds of large mammals, particularly caribou.

Approximately 10,000-5,000 years ago the tundra converted to boreal forest, then the mixed deciduous forest we see today, as the climate warmed and dried. Due to a decline in many of the larger species, humans relied on smaller game, freshwater fish and wetland plants for food sources. Regular seasonal settlements emerged and settlement sites existed throughout the watershed. Based on locations of found artifacts, it is understood that people settled near falls where fishing was easier, such as those currently beneath Talbot Mills Dam.

5,000-3,000 years ago the population of hunter-gatherers increased. Fishing weirs found dating to this period suggests increased fishing and improved fishing methods.

3,600-1,000 years ago people had established long distance trading routes, as indicated by non-local materials found in tools from this period. People began farming, as indicated by the earliest evidence of agriculture in the region. Anadromous fish continued to be an important food source, along with deer and turkey. Stone artifacts from this period have been found within the SuAsCo watershed.

1,000-450 years ago Tribal territories, as they existed in the European Colonial Contact period, including the Nipmuc and Pawtucket territories within the watershed were established. Click below to explore an interactive map of native territories, languages and treaties within the SuasCo watershed and around the globe, developed by  Native Land Digital .

These are the rivers in the Merrimack River Watershed.

Historically, prior to colonization and the industrial revolution, fish could move freely up and down these streams.

Sediments and nutrients were transported freely from upstream tributaries, downstream to the marsh, allowing the river to support a variety of habitats and ecosystems.

Migratory fish used to travel from the oceans, to the mouth of the Merrimack River...

they swam up the mainstem of the river…

and some returned to spawning grounds in the lower tributaries, while others continued upstream.

Some returned to spawning grounds in the Shawsheen River...

while others migrated up the Concord River.

Many continued up the main stem. An observation in an early biological survey of the Merrimack River in from the end of the 18th century recounted shad at Amoskeag Falls:

“so thick as to crowd each other in the passage up the falls… you could not put in your hand without touching some of them.”

Marston, P.M. and Gordon, M. 1938. Notes on fish and early fishing in the Merrimack River system. Biological survey of the Merrimack watershed. New Hampshire Fish and Game Commission, Concord: 186-198.

Migratory fish have been observed as far upstream as...

the upper sections of the Pemigewasset River, in the White Mountains.

Relative to this, the swim to Talbot Mills Dam is quite close to the ocean.

The green area shows the historical extent of habitat available to migratory fish for spawning, or for eels, for spending the majority of their lives.

Today, almost all of that habitat is blocked by estimated 3,148 dams.

Approximately 2,648 in the New Hampshire portion of the watershed and 500 in the Massachusetts portion.

Now fish can still make it into the mouth of the river,

and up the lower part of the Merrimack River...

but most of the tributaries are no longer accessible due to dams.

Some dams like the Essex Dam in Lawrence and the Pawtucket Dam in Lowell have ways for fish to pass up and down stream. Because of this, they are shown as green circles.

Just downstream of Pawtucket Dam, the Concord River flows into the Merrimack River. Talbot Mills Dam is located just a few miles upstream from the confluence, and upstream of Centennial Island dam, which currently has a fish ladder for passage.

While fish ladders and fish lifts with downstream bypass do make it possible for some fish to pass up and downstream, it is not guaranteed that all fish can pass and requires an extensive amount of maintenance.

Where dam removal is impractical, this can be an alternative. From the perspective of fish passage, dam removal is the best way to ensure fish are able to move up and down the river.

Amoskeag Dam in Manchester, NH, also has fish passage, but fish are met with additional barriers a few miles upstream. Hooksett Dam in Hooksett, NH, and Garvins Falls Dam in Bow, NH, currently lack upstream fish passage infrastructure.

The green area shows the habitat available to migratory fish today, relative to the historically available area, in red. The green area assumes fish can pass through various fish passage facilities, which is not always the case.

Most fish need slower moving waters of the tributaries to spawn and survive. While restoration efforts have improved access to tributaries from just 40 years ago, there are still very few tributaries accessible for migratory fish.