Frequently Asked Questions

What are the plans for the South Branch River restoration project?

The Cole’s Mill dam is being considered for removal. The potential project would involve a study to determine project feasibility, engineering and design, permitting, deconstruction of the dam, and restoration of the river channel. It would also include the restoration of the floodplain and riparian habitats that make up a healthy river system, including the area upstream of the dam that currently holds water (known as an impoundment).

Why is the Cole’s Mill dam being considered for this project?

The Cole’s Mill Dam removal project was identified by a scoping effort aimed at restoring natural resources in the Raritan River Watershed. This effort (described in more detail below) involved the input of over 150 stakeholders from the public, and prioritized projects with the most potential for ecological uplift. The Cole’s Mill Dam removal project was selected because of the potential for great ecological benefits to fish and wildlife habitat, water quality, and aquatic connectivity. The South Branch of the Raritan River ( which the dam spans) begins at Budd Lake in Morris County and merges with the North Branch in Bridgewater Township to form the mainstem Raritan River. From there, the mainstem flows out to Raritan Bay (see map below). This project is part of a larger effort to restore the Raritan River and its tributaries to a free-flowing natural state.

Additionally, the project is considered high priority because it will benefit the public through enhanced access for recreational fishing, potential improvements in flooding, as well improved public health and safety.

In January 2018, approximately 30 feet of the dam was damaged by ice and resulted in a breach of the dam. As a result of this incident, NJDEP Bureau of Dam Safety notified the current dam owner in writing that the dam must be repaired or removed. The breach and associated debris accumulation has altered the flow pattern just downstream of the dam in a way that threatens to erode and undermine Raritan River Road.

What is the Cornell-Dubilier Electronics Superfund Site and what does it have to do with the proposed project?

The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA aka “the Superfund Law”) allows for the restoration or replacement of natural resources that were lost or injured as a result of the release of hazardous substances. The Natural Resource Trustees (in this case the U.S. Fish and Wildlife Service, the National Oceanic and Atmospheric Administration, and the New Jersey Department of Environmental Protection) can initiate a natural resource damage assessment and restoration (NRDAR) process to compensate the public for the losses of these resources and the services that they provide.

The Cornell-Dubilier Electronics, Inc. Superfund Site is located in South Plainfield, Middlesex County, New Jersey. As part of the NRDAR process, the Trustees developed and jointly filed natural resources damages claims with potentially responsible parties seeking monetary compensation for injuries to natural resources caused by the release of hazardous substances and pollutants at or from the Cornell-Dubilier Site. Recovered damages are intended to restore, replace, rehabilitate and/or acquire the equivalent of injured natural resources, including their supporting habitats, to compensate the public for injuries to natural resources. The Trustees facilitated a watershed-wide scoping effort under which 150 non-government organizations, academic institutions, and government agencies were invited to propose ecological restoration projects. The trustees then evaluated and selected restoration alternatives based on many criteria. To allow for public input, the plan was released for a 30-day public review and comment and then finalized in 2021. The Cole’s Mill dam removal project was selected as a Tier 1 (highest priority) project in this plan, which is viewable at: RESTORATION PLAN AND ENVIRONMENTAL ASSESSMENT

Who decides that a dam should be removed?

The decision to remove a dam is made by varying entities, depending on the regulatory oversight of the dam. In most cases, the dam owner itself is the decision-maker, often deciding that the costs of continuing to operate and maintain the dam are more than removing the dam. State dam safety offices can order a dam to be removed if there are major safety concerns. State fish and wildlife offices are also often involved in the decision-making, particularly when the goals of the project include restoration of habitat for migratory and resident aquatic species.

Who is paying for the project?

All project costs associated with a possible dam removal would be paid for through the monetary compensation claims associated with the Cornell-Dubilier Electronics natural resource damage assessment and restoration funds. Repairs to and future maintenance of the dam would be the responsibility of the dam owner.

What are the potential outcomes of the project?

A study will be conducted to determine the feasibility of the project and assess the potential impacts of full dam removal. This will include surveys of the land, water, sediment, and wildlife, as well as considerations of public safety and potential impacts to infrastructure. The results of these investigations will inform how the project advances. If removal moves forward, engineering design alternatives will be developed and all necessary permits will be acquired before removal takes place. The final restoration may include new recreational access in addition to habitat restoration. This process is anticipated to be completed in 2026.

What are the benefits associated with the project?

The main public safety benefit associated with the project will be the removal of an in-stream barrier that poses significant risks to the public, including the possibility of drownings and undermining River Road. The removal of a dam and restoration of the river channel is intended to improve conditions for native coldwater-dependent fish species including trout. Impoundments (water held above dams) often experience high temperatures and poor water quality during summer months that cause conditions that are unsuitable for aquatic wildlife and contribute to bacterial contamination. The area affected by this can be extensive. We expect that dam removal and associated river restoration will improve these conditions for native fish species, freshwater mussels, and other aquatic life. Additionally, other wildlife such as birds that feed on these species will benefit from the increased food sources.

From a recreational perspective, this improved fish habitat will enhance recreational fishing opportunities and may result in associated local economic development. Dam removal facilitates long term environmental benefits from the services provided by improved fish and wildlife habitat, water quality, and a restored, free-flowing river. Possible improvements to local flooding and reduced maintenance and repair costs to nearby infrastructure could also result from the dam removal.

What are the potential downsides associated with the project?

Dam removal does result in fundamental changes to the local environment. The impoundment will be eliminated, and with it the flat-water habitat that was created, which will be replaced by the naturally free-flowing river. Wetlands surrounding the reservoir may also be drained, although new wetlands are often created both in the newly restored river reach above the former dam site and in the river below. Sediments that collect behind a dam, sometimes over hundreds of years, may contain contaminants. Removal of these toxic materials is often extremely expensive, and the threat of re-suspending these in the process of dam removal has the potential to damage downstream water quality and threaten the health of fish and wildlife and water users. These impacts, however, can be prevented through proper removal techniques, the need for which will be identified in the first phase of evaluating project feasibility. Short term impacts of the dam removal itself can include increased water turbidity and sediment buildup downstream from releasing large amounts of sediment from the reservoir, and water quality impacts from sudden releases of water and changes in temperature. These short-term impacts are greatly outweighed by the quick recovery of the system and the long-term benefits that result.

What will happen to the ponded water just upstream of the dam and the wildlife that uses it?

Depending on the results of the technical studies that will occur prior to dam removal, the water will likely be released slowly downstream in a way that will not negatively impact downstream resources. During dam deconstruction activities, the project team will monitor for any sensitive wildlife species that need to be salvaged or relocated such as turtles. There will be a short period in which the sediments in the area of the former impoundment will be exposed as the transition to natural floodplain habitat takes place. Once the stream channel has been reformed, banks will be stabilized to prevent erosion and revegetated. Native plants that will provide food and shelter for wildlife and pollinators will be installed, creating a lush green riparian area. Breeding and overwintering native waterfowl that may currently utilize the impoundment (such as mallards, mergansers, and buffleheads) will not be negatively impacted as they also utilize riverine habitat.

Will there be an increase in flooding because of the project?

In heavy rainfall or flooding, some dams are designed to hold back some of the water flowing downstream, protecting people and property downstream from higher water. This naturally results in higher water upstream of the dam, but auxiliary spillways are designed to pass excess flood waters downstream. However, most dams in the state are not designed to function as flood control structures. They are “run of the river” dams designed to hold relatively stable water levels in the impoundment.

Cole’s Mill dam is a run of the river dam and was not designed to hold back flood waters. As part of the permitting phase of any dam removal project, NJDEP Bureau of Dam Safety will need to evaluate whether the engineered restoration design will have any impact on flooding. Should any increase in flooding be shown in the engineering design, the project would not be allowed to proceed. Only projects that show no impact or reduced flooding impacts would be allowed to proceed.

Is the dam considered historic?

Part of the dam removal planning process is to assess the project’s potential to impact historical resources. In accordance with the National Historic Preservation Act, the State Historic Preservation Office must be consulted about the project as early as possible in the project planning process. They may recommend further study to determine the historic value of the site, based on both archaeological and architectural criteria. At some project sites the dam’s historic contributions are honored with interpretive signs, recovered mill stones and other information. In other cases, when a dam is historically significant, dam removal may not be appropriate and other alternatives may need to be considered.

Does the dam pose a public safety concern?

While all dams are potentially dangerous, low-head dams like Cole’s Mill dam are especially dangerous because the water around them often appears to be tranquil and inviting. Many drowning victims deliberately jump from or float over them without knowing the risks. Others are caught unaware, as low head dams are notoriously difficult to spot from upstream. The victims of these dams include many would-be rescuers and first responders who lost their lives trying to save others caught in the hydraulic current.  About 91% of drownings and other dam-related deaths occur in the period from April to August.

Who oversees dam regulation in New Jersey and how will any potential repair or removal be regulated?

In New Jersey, the NJDEP Bureau of Dam Safety oversees most dams. The Safe Dam Act can be found through N.J.S.A. 58:4 and the Dam Safety Standards can be found through N.J.A.C. 7:20. There are additional regulatory agencies that will need to approve of any restoration activities, including but not limited to NJDEP Bureau of Dam Safety, NJDEP Division of Land Resource Protection, Hunterdon County Soil Conservation District, NJDEP Historic Preservation Office, and NJDEP Bureau of NJPDES Stormwater Permitting and Water Quality Management.

How will keeping the dam in place affect habitat and wildlife?

Dams are hydrological barriers to fish passage and can seriously impede migration and natural movement of fishes, which can result in decline and even local extinction of species. As fish cannot move freely upstream of dams that are complete barriers, populations may become isolated, which can result in reduced genetic diversity and population stability.

In addition to being a complete barrier to fish passage, the Cole’s Mill dam creates a 7-acre impoundment that extends over a half a mile upstream of the dam, where sediments have accumulated and water has become ever more shallow. The shallow water behind the impoundment also creates a thermal dynamic that leads to warmer water, which degrades habitat for coldwater species and also lead to higher bacteria counts that could create unsafe conditions for recreation. Stillwater behind the dam often becomes habitat for invasive species like non-native aquatic plants and fish, which reduce habitat quality further. Nuisance species such as Canada geese are also drawn to these habitats and can cause further water quality issues and degrade aesthetic value.

How will removing the dam affect habitat and wildlife?

Dams alter the natural physical, biological and chemical functions of rivers. And, since healthy rivers are considered the lifeblood of healthy habitats, dams can result in unsustainable and degraded conditions for a variety of aquatic and terrestrial species. The habitats that have been created solely because of the dam’s presence will change if the dam is removed.

Removal of the Cole’s Mill Dam would restore fish passage for approximately 11 miles to Nunn’s Mill Dam, the next dam upstream on the South Branch Raritan River. Removal of the Cole’s Mill Dam would additionally provide resident fish passage for five miles downstream, through Ken Lockwood Gorge to the Lake Solitude Dam. Summertime fish kills are not uncommon at the Ken Lockwood Gorge due to water quality issues, particularly increased water temperature. Removal of the Cole’s Mill Dam would help to conserve coldwater habitat in the South Branch Raritan and improve recreational fishing in the Ken Lockwood Gorge. Dam removal will improve fish passage for resident and diadromous species such as American eel and will reduce stream temperatures for coldwater species such as brook trout, brown trout, and rainbow trout.

Water quality and habitat improvements will improve conditions for all species, including several

species identified by the State of New Jersey as having Greatest Conservation Need, including

American brook lamprey, bluespotted sunfish, cutlips minnow, eastern mudminnow, fallfish, margined madtom, redbreast sunfish, satinfin shiner, shield darter, swallowtail shiner, and yellow bullhead. Water quality and habitat improvements will also benefit several mussel species, including alewife floater, eastern, elliptio, and eastern floater. Birds, amphibians, and reptiles will also benefit from the restored river and riparian habitat.

Will fishing and other recreational activities change if the dam is removed?

Dam removal improves the health of the river and aquatic habitat, typically to such an extent that anglers can look forward to increased numbers of fish and more places to fish for them. In some cases, removing a dam will change the type of fishery. For instance, a warm water fishery may be restored to a cool or coldwater fishery. In many cases, free-flowing rivers allow a wider variety of warm, cool and coldwater species to seasonally occupy portions of the same river, providing greater fishing variety. Anglers often like to fish right below dams, and some may oppose removal because they feel they’ll lose a good fishing spot. But it’s important to realize that the fish aren’t necessarily there because it’s good habitat, they’re often there because they’re prevented from moving further upstream. The river will ultimately become safer for all recreational activities because the public safety concern for drowning at low-head dam sites will be removed.

What are the next steps and expected timeline?

Feasibility studies will be conducted to determine whether dam removal will be the best course of action. Those studies will include topographic and bathymetric surveys, wetlands delineation, sediment sampling, geomorphic survey, vegetation survey and wildlife survey. They will be compiled into a report containing results from the field investigations along with design alternatives and be presented at another public outreach event sometime during the Summer of 2024.

September 2023 Project Awarded

November 2023 Public Outreach Event

Dec 2023 / Jan 2024 Topographic Survey

Feb / March 2024 Field Investigations

May 2024 Public Input

July 2024 Conceptual Design & Feasibility Report

November 2024 30% Engineering Design

April 2025 60% Engineering Design

October 2025 90% Engineering Design & Regulatory Approvals

December 2025 Final Engineering Plans