Tag: shad

Weston Mill Dam Removal

Article and photos by John W. Jengo

The Weston Mill Dam and the former Weston Mill gristmill and sawmill site are located approximately 1.5 miles upstream of the Millstone River’s confluence with the Raritan River, and immediately downstream of the Weston Causeway (Wilhousky Street) Bridge in the Borough of Manville and the Township of Franklin, Somerset County, New Jersey. The dam crest length was approximately 112.5 feet long and there was a concrete approach apron that ranged in thickness from 5 to 6.75-inches that extended 17.5 to 18.5 feet upriver of the dam spillway. The location of the mill was depicted on early Colonial-era and Revolutionary War military field maps, and the mill and dam were picturesque landmarks that were often photographed by local residents, including images included in the book Franklin Township [NJ] – Images of America, published in 1997.

Through an intensive deed search, I determined that a gristmill and dam were established on the east bank of the Millstone River at the project area circa 1747, most probably built by Abraham Brokaw, and the mill was subsequently involved in a Revolutionary “Forage War” skirmish between British and American forces on January 20, 1777 while under the ownership of Abraham Van Nest.  Recovery of two cornerstones during 1983 salvage operations suggest major mill building and rebuilding efforts occurred in 1803 and 1844 by John M. Bayard and Isaac R. Cornell, respectively.  Though the mill remained active at this site into the early twentieth century (it was the most productive mill in the Millstone River/Stony Brook drainage), under various private owners and incorporations (Weston Mill Company, Inc.; Community Flour Mill and Grain Company; Union Mills Company, Inc.), and the dam underwent significant structural repairs between circa 1922 and circa 1948 by its last owner (Wilbur Smith), it ultimately fell into disuse and disrepair. On May 31, 1982, the mill building partially collapsed into the Millstone River. Mill artifact salvage operations were initiated on June 25, 1983 but were abandoned when arson claimed the collapsed structure on July 7, 1983.

When I first began assessing this dam in 2009 as a candidate for removal, the Weston Mill site included the brownstone and concrete foundation remains of a gristmill that had enclosed a turbine room (formerly the water wheel pit) and a tailrace room, and there were associated powertrain components scattered throughout the site, including multiple bevel gears, possible mortise and pin gears, sprocket gears, drive shafts, counter shafts, flat belt pulleys, and other mill-related power-train apparatuses. A concrete coring project conducted in August 2015 at five representative locations on the dam approach apron (the same effort that determined the thickness of the apron) revealed two concrete approach aprons, which suggested that the dam was reinforced or rebuilt with concrete in two different periods in the early- to mid-twentieth century and that this run-of-the-river dam may have been built on top of a timber crib dam of unknown age.

Routine visits to the dam site over the next eight years would indicate that beginning in 2015, the eastern 78 feet of the dam crest (i.e., the top of the spillway) and spillway began to noticeably subside and detach from the concrete approach apron, placing undue stress on the riverward mill foundation wall to the east.  By mid-2017, the collapsing dam crest and spillway had subsided almost to the level of the downstream pool elevation, had deflected outward some five feet downriver, and in doing so, the flow of the river was redirected toward the mill ruins on the east bank, potentially causing adverse effects to the mill foundation and complicating the dam removal.

The dam removal and the engineering plans were re-designed to include emplacing scour protection around the Weston Mill foundation walls to arrest the damage to the ruins and preserve the remaining fabric of the site for future study.  The first step in the dam removal process, which commenced on August 14, 2017, was to initially breach a portion of the dam to reduce the differential head between the upstream and downstream pools. The initial breach width of 35 feet, located near the center point of the dam, produced the desired upstream pool drawdown and a relatively low current velocity through the breach. Once the upstream impoundment had drained, the contact between the concrete approach apron and the riverward mill foundation wall was accessible to be saw cut to isolate the apron from the mill wall prior to further demolition. This was done to ensure that neither the weight of the demolition excavator or the vibration of the hydraulic hammer would destabilize the riverward foundation wall.

After the saw cut was completed, the concrete approach apron, an underlying concrete sub-apron, and dam spillway were carefully detached and removed.  Imported rip rap was then emplaced around the mill foundation walls. My experience working on the rivers of this watershed indicated that natural sedimentation from storm events would eventually blanket and in-fill the rip rap, enhancing the stability of the scour protection armament. Finally, a restored river channel thalweg were excavated and contoured appropriately.  It was during these excavations that segments of a timber crib dam, secured to the river bed by using 17.5-inch to 20.5-inch long, 1.125-inch square iron spikes, were extracted that clearly indicated that the pre-concrete dam structure was a timber crib construction.  Three primary types of roughly square timbers believed to be part of the timber crib dam were identified: 13-foot long lap jointed foundation logs with iron spikes, 9.25- to 9.75-foot timbers with two mortise joints (some with intact dowels), and 3.8-foot timbers with tenons at one end.  Several timbers of this historical structure were saved and donated to the Borough of Manville, Delaware and Raritan Canal State Park, and NJDEP, who had purchased the dam site in 2013 from a private owner, an acquisition that allowed the dam removal to proceed.

Monitoring of the river reach above the former Weston Mill Dam in spring 2018 following the August 2017 dam removal found definitive evidence of successful American shad spawning, an astonishing and long-awaited result given this river reach had effectively been blocked to migratory fish for over 270 years.  Five juvenile shad averaging 4.3 inches in length were found 4.5 miles upstream of the dam at the base of Blackwells Mills Dam during a monitoring visit, highlighting yet again the dam removals can yield near-instantaneous positive results even after centuries of impeding fish migration and spawning.

Video of the Weston Mill Dam removal can be viewed here:

Endnote: Because of the archaeological discoveries made before and during the dam removal, and the rich cultural history of Weston Mill, a standalone video on the History of Weston Mill was developed and can be viewed here:

John W. Jengo, PG, LSRP is a licensed Professional Geologist in several Northeastern and Southeastern states and a Licensed Site Remediation Professional in New Jersey. John works as a Principal Hydrogeologist in an environmental consulting firm in southeastern Pennsylvania. He has degrees in geology from Rutgers University (1980) and the University of Delaware (1982). Over the last 30 years, he has conducted the characterization and remediation of large, complex contaminated industrial sites throughout New Jersey, Pennsylvania, and Delaware. He played a key role in Natural Resource Damage (NRD) assessments that led to groundbreaking legal settlements to remove numerous low head dams on the Raritan and Millstone Rivers to restore historically significant migratory fish spawning runs. As technical project manager, he planned, permitted, and successfully managed the removal of the Calco Dam, the Robert Street Dam, and the Nevius Street Dam between 2008-2013, and the removal of the Weston Mill Dam on the Millstone River in 2017, along with leading the archaeological investigation of the former Weston Mill in the Borough of Manville and Franklin Township.

May 21 – General Meeting: All about Forage Fish!

At our monthly meeting on May 21 (10-noon) we will welcome Zack Greenberg with the Pew Charitable Trusts for a special presentation on forage fish and ecosystem-based fisheries management (EBFM).

Zack is a Senior Associate at The Pew Charitable Trusts, focusing on marine conservation issues as a part of their U.S. Oceans, Northeast team. At Pew, Zack is raising awareness about the importance of adopting a big picture approach to marine conservation called ecosystem-based fisheries management or “EBFM”, which recognizes that every part of the marine ecosystem, from seagrass to whales, are interconnected. Zack’s primary focus is to advance protections for forage fish like menhaden, river herring and shad. How these essential forage species are managed has huge implications for the future of the ocean food web and many of the sportfish, marine mammals and birds we enjoy today.

The meeting will be held from 10-noon in the Middlesex County Planning Offices at 75 Bayard Street, New Brunswick, NJ – 5th floor mid-size conference room.

Parking is validated for those parking on floors 5 and higher in the RWJ Wellness Parking Deck located at 95 Paterson Street, New Brunswick, NJ 08901. Be sure to bring your ticket to the meeting for validation.

For more information contact Heather: hfenyk AT lowerraritanwatershed DOT org

Presentation Topics

  • Magnuson-Stevens Act
  • Forage and EBFM
  • River Herring and Shad

Magnuson-Stevens Act

The MSA is the primary law governing marine fisheries management in the United States. It setup many of the regulatory systems and management tools we are familiar with today. The MSA is credited with rebuilding 43 once-overfished populations since 2000, but U.S. fisheries still face significant challenges, including continued vulnerability to overfishing, habitat destruction, and changing ocean conditions—factors that highlight a need to strengthen, not weaken, the MSA.

Forage and EBFM

Forage fish are the foundation of healthy marine ecosystems. Sportfish, like striped bass, summer flounder, and bluefish, as well as popular wildlife, such as osprey and whales, need healthy forage fish populations to thrive. Despite forage fish being an increasingly valued commodity, the MSA currently does not ensure they are managed to account for their ecological role. Protecting forage is the best way to guarantee abundant food and a healthy ocean for marine life, which draws millions of people to the coast for fishing, boating, diving and other recreational opportunities.

River Herring and Shad

River herring and shad once supported large commercial and recreational fisheries. However, the damming of spawning rivers, combined with habitat degradation, overfishing and bycatch at-sea have depleted their populations. In February, the Atlantic mackerel fishery was shut down due to bycatch of river herring and shad, and in March the Atlantic herring fishery closed in southern New England for the same reason. With effective federal management and conservation policies at-sea, rivers up and down the East Coast could once again come to life with thousands of migrating fish.

Dam Surprised Fish

Article and photos by Joe Mish

The sea run shad, striped bass and herring that gather at the mouth of the Raritan River attract animals high on the food chain such as this harbor seal. Whales and dolphin have also been sighted over the last few years not in small part from the contribution of the Raritan River and its sweet water branches.

The spring-fed north and south branches of the Raritan River join in a marriage of sweet water at their confluence, on an endless journey to the sea. Each hidden spring and brook along the way, contributes its own genetic identity, mixed in a final blend at the mouth of the Raritan River.

Where the fresh water meets the salty sea, the ebb and flow of tides stir the brine into fresh water to create a stable buffer zone of brackish water.

These back bays and estuaries formed at the mouths of rivers are a perfect place for young of the year striped bass to gain in size before going offshore to migrate. American, hickory, gizzard shad, river herring, such as blueback herring and alewives also gather here and search for ancient breeding grounds located far upriver.

In the time before dams, sea run fish migrated far upstream into the north and south branch. Fishing was a robust industry in early colonial times where the seasonal migration of herring and shad was a profitable business.

The construction of dams to power mills along the river put a halt to upstream commercial fishing. The mills and dams were not welcomed by colonists who made a living from the seasonal fisheries. One account tells of early settlers in the mid 1700s, unhappy with a mill dam just below Bound Brook, making nightly raids to dismantle the dam and allow shad to continue their upstream migration.

Fast forward to today, the river still flows to the sea and the shad and herring gather to swim upstream.

In 1985 pregnant shad from the Delaware River were transplanted to the South Branch as part of a program to restore a shad migration along with planned dam removals.

Dams that have blocked migrating fish have recently been removed. The Calco dam near the former Calco Chemical Company built around 1938, cleared the way for migrating fish to reach the confluence of the Millstone and Raritan where a flood control dam was built. Known as the Island Farm weir, completed in 1995, it includes a viewing window and fish ladder to allow the dam to be bypassed by fish travelling upstream.

As part of the shad restoration project, volunteers working with Rutgers scientists tag shad and herring in an ongoing effort to gauge the success of the fish ladder and restoration efforts. Preliminary findings can be accessed at, http://raritan.rutgers.edu/wp-content/uploads/2015/10/NJDEP-2013-American-shad-restoration-in-the-raritan-river.pdf

A live underwater camera is placed at the dam each year after threat of ice has past. The camera is now operated by Rutgers University and may be seen online at  http://raritanfishcam.weebly.com/fish-guide.html and at http://raritan.rutgers.edu/resources/fish-cam/

Aside from the Calco dam, three of five dams upstream of the Island Farm Weir, two dams on the Raritan, the Nevius street and Robert street dam and one on the Millstone have been removed. All in anticipation that the head dam at Dukes Island Park and the low dam at Rockafellows Mills on the South Branch will eventually be deconstructed.

See the above link for the video of the Nevius street dam removal. Go to MENU, open videos/multimedia to see Nevius street dam deconstructed.

See this link for a look at the Duke’s Island dam today; https://vimeo.com/259404286

The dream to restore our rivers and fisheries to their unmolested glory is well on the way to reality. Bald eagles now nest along the Raritan and its branches, soon to be joined by spawning shad and herring.

The vision of a pristine river valley, interrupted by 300 years of abuse and neglect is slowly emerging from the river mist as a magical apparition. The magic supplied by the hard work of Rutgers scientists and dedicated volunteers who echo the words of Rutgers president Thomas, who served in 1930, “Save the Raritan”.

As an aside to this article, I will share a sobering and emotional experience involving the Island Weir Dam that took place in 1995. The intent is to emphasize the importance of safety while paddling in general and especially when near dams or in cold water.

See page three of this link for a description of what happened that day: http://www.wrightwater.com/assets/25-public-safety-at-low-head-dams.pdf

I was paddling on the Delaware and Raritan Canal which parallels the Millstone River about two miles from where the dam is located at the confluence of the Millstone and Raritan rivers. This was a training session for a cold water canoe race that takes place each April in Maine. I am an experienced paddler, familiar with cold water immersion and so was wearing a wet suit with a dry top and pants along with a life jacket/pfd while on the calm water in the canal.

As I neared the end of my trip at the Manville causeway, several police cars slowly drove by and turned around as if searching for something. Sirens were wailing and more police and rescue vehicles were seen and the road blocked off. First thought was the body of a woman who was reported to have ended her life in the Millstone a week before was found.

As it turned out a kayaker and two companions in a canoe decided to run the dam. According to my recollection of the news article; the canoe made it through first, while the kayaker who followed, failed to clear the dam and was stuck in the hydraulic.

According to the news article, ‘the experienced paddlers’ wore no thermal protection or pfds when they ran the dangerous dam. It was reported that the canoers paddled back to help their companion and they capsized in the hydraulic. Once you cross that line which marks the downstream flow from the water cycling upstream, you will be pulled into the hydraulic.

The kayaker and one of the men in the canoe were washed out of the turbulent water but the other was lost, his body never recovered.

A hydraulic occurs when the weight of falling water creates a hole which is then filled by downstream water being pulled upstream in an endless re-circulating current parallel to the dam. Low head dams may be altered to prevent or mitigate a hydraulic.

There is a point of no return where you can actually see a line that separates the water flowing downstream from the water flowing back upstream to power the hydraulic.

Island Weir Dam at the confluence of the millstone and Raritan River. You can see the horizontal shelves that are the fish ladder in the center and the subsequent stepped redesign to mitigate the dangerous hydraulic.

There have been several more drownings involving dams on the Raritan and its branches. I recall another at the Headgate, which is the dam created by the Duke estate below the confluence of the North and South branches. The paddler went over and was lost in the hydraulic below.

This is the headgate dam at Dukes Island Park. Created to collect river water via the Dukes canal to power the estates and supply water to the series of ponds built at decreasing elevations to allow the water to return to the river by gravity.

No warning signs are posted to alert paddlers to the danger ahead. On the downstream face of the dam is a warning to keep off.

Too little too late warning.

Paddling on the South Branch from Rockafellow’s mill rd, just below the low head dam that forms Red Rock Lake, this note was placed on my windshield. Though I was no where near the dam, contrary to what the note states, the message was at once heart breaking and shown here, now serves as a warning to all; beware of the dangers of low head dams.

This sign is placed about 5 football fields above the dam at red rock lake on the South Branch. It’s placement a puzzlement that mitigates its message.

Dam at Red Rock Lake.

Though rivers like the South Branch and North Branch are reputed to be no more dangerous than a swimming pool, tragedy can strike when least expected. Strainers, trees that fall into the river blocking passage, can snag and capsize a boat and entangle the paddler in its branches under pressure of a fast current. Low head dams can drown a paddler by immersion or entanglement on debris as the paddler is unable to wash out of the turbulent recycling water. Search on line to get an idea of how widespread is the danger of obscure low head dams and loss of life across the country.

Paddling when river temperatures are well below normal body temperature requires thermal protection no matter the air temperature. Wearing a pfd alone will not be enough to survive if your body temperature drops before you can be rescued or self rescue. Such was the case of a paddler on Round Valley reservoir a few years ago.

Typically water temp during the winter and early spring on the South Branch is 41 degrees. More than enough to cause a spasm to block your ability to breathe even before hypothermia sets in. See this link for a detailed explanation of the effects of cold water immersion. Remember, ‘cold water’ does not have to be that cold.


Overturning in fast water, a boat can instantly fill with a hundred gallons of water. Each gallon weighing 8 pounds, can pin or crush a paddler between the canoe and any obstruction. Such was the case on a locally sponsored canoe trip in shallow water on a beautiful day on the South Branch. One paddler was trapped under the canoe in a strainer. Eventually he popped out from under the boat, shaken but safe. The canoe was stuck fast in the strainer, filled with hundreds of pounds of water. Never be downstream of a capsized canoe.

Tragedy can occur on the calmest day under brilliant blue skies, always wear a pfd and be alert to potential dangers, especially dams.

Low head dam across the North Branch just above rt 202 makes a difficult passage during low water portage and a dangerous hydraulic during high water.

Author Joe Mish has been running wild in New Jersey since childhood when he found ways to escape his mother’s watchful eyes. He continues to trek the swamps, rivers and thickets seeking to share, with the residents and visitors, all of the state’s natural beauty hidden within full view. To read more of his writing and view more of his gorgeous photographs visit Winter Bear Rising, his wordpress blog. Joe’s series “Nature on the Raritan, Hidden in Plain View” runs monthly as part of the LRWP “Voices of the Watershed” series. Writing and photos used with permission from the author.

LRWP response to Draft RP/EA for American Cyanamid Co. Superfund Site

The LRWP has submitted the following letter in response to NOAA’s Invitation to Public Comment on their “Restoration Plan/ Environmental Assessment Draft (RP/EA) for the American Cyanamid Co. Superfund Site, Bridgewater Township, Somerset County, New Jersey”:

May 23, 2016

Carl Alderson
NOAA Restoration Center – Sandy Hook Office
JJ Howard National Marine Fisheries Science Center
74 Magruder Rd, Highlands, NJ 07732

RE: American Cyanamid Draft RP/EA

Dear Mr. Alderson –

The Lower Raritan Watershed Partnership has reviewed NOAA’s proposed Restoration Plan/ Environmental Assessment (RP/EA) for the American Cyanamid Co. Superfund Site, Bridgewater Township, Somerset County, New Jersey and fully supports the proposal for primary and compensatory restoration activities.

The LRWP is New Jersey’s newest watershed association, formed in 2014 to address legacy contamination and current pollution in the Raritan River and the Lower Raritan Watershed. Our mission is to conserve, enhance and restore the natural resources of the New Jersey Watershed Management Area 9, the Lower Raritan Watershed. We believe that not only will removal of the Weston Mill Dam on the Millstone River directly improve resources impacted by legacy contamination, it is our understanding that the proposed project will benefit a broad spectrum of the Raritan River’s ecology and will likewise enable other environmental and human use benefits. Significant ecological, environmental and human use benefits have in fact already been realized following recent removal of a series of dams (Robert Street, Nevius Street and Calco) on the lower portion of the Raritan River between the towns of Bridgewater and Bound Brook. Likewise, we expect that design of technical fish passage at the Island Farm Weir (located on the Raritan River) will advance multiple Lower Raritan Watershed stakeholder goals.

The LRWP is also aware that the removal of the Weston Mill Dam on the Millstone River, as well as future modifications at the Island Farm Weir to include a technical fish passage at the Island Farm Weir on the Raritan River, will expand access to several thousand acres of non-tidal freshwater mid to upper reaches of the Raritan River’s major tributaries. Removal of Weston Mill Dam and the construction of a technical fish passage at Island Farm Weir will significantly enhance maturation and rearing habitat for striped bass, American shad, American eel, blueback herring, and alewife, and should significantly increase the abundance of anadromous and catadromous species, which will improve the ecological health of the Raritan River.

The LRWP’s only concerns with NOAA’s proposal are short term sediment transport impacts following dam removal. However, we are confident that NOAA’s plan to reduce potential environmental consequences is sound and further expect that the proposed projects will provide long term restorative benefits to water chemistry, specifically decreased water temperatures in formerly impounded sections, and increased dissolved oxygen concentrations. These changes will benefit riverine biota from the most basic food chain level up to the top predators for many years to come.

Enhancing fish populations in the Raritan River system is important for fresh and marine ecosystems. It is especially appropriate as the National Marine Fisheries Service (NMFS) lists the estuarine portion of the Raritan River as an important migratory pathway for anadromous alewife and blueback herring, species which NOAA lists as of special concern. The Lower Raritan Watershed Partnership feels that the proposed projects could help to reverse declining population trends, and anadromous fish returning to spawn each spring in the Raritan River provide an attraction to the general public in the Raritan River Basin. The removal of the Weston Mill Dam on the Millstone River and feasibility analysis and design of technical fish passage at the Island Farm Weir are important to the LRWP and we fully support the proposed projects.


Heather Fenyk, Ph.D., AICP/PP
President, Lower Raritan Watershed Partnership

The National Oceanic and Atmospheric Administration, the Department of Interior, and the State of New Jersey invite public comment on a proposed plan.
The Draft RP/EA is available at the following website:


The public comment period on this plan ends June 10, 2016.

To request further information or an additional hard copy of this document or to submit your comments, please contact Carl Alderson at (732)371-0848, NOAA Restoration Center – Sandy Hook Office, JJ Howard National Marine Fisheries Science Center, 74 Magruder Rd, Highlands, NJ 07732 or by email at Carl.Alderson@noaa.gov. Please put “American Cyanamid Draft RP/EA” in the subject line.