Removal of the Columbia and Remnant Dams

State TrusteeNew Jersey Department of Environmental Protection

Case Name:


United States of America

Restoration Types:

Habitat Creation; Habitat Enhancement; Population Support; Recreation


Affected DOI Resources:

; Other


Knowlton Township



Project Description

The Paulins Kill is a 41.6-mile tributary of the Delaware River in northern New Jersey. The downstream-most barriers, the Remnant and Columbia Dams, prevented anadromous fish, including American shad and river herring, from accessing the river for over a century. Located 0.1 miles upstream of the confluence with the Delaware River, construction began on the Remnant Dam in 1901 to provide hydropower for nearby communities and create an impoundment to harvest ice during the winter. A major flood in February 1902 stopped construction and the partially built dam was abandoned. The Columbia Dam, located 0.3 miles upstream from the confluence, was constructed in 1909 by the Warren County Power Company to generate electricity for local usage. The 18-foot high, 330-foot wide dam operated until the 1950s when Warren County Power Co. was absorbed by the New Jersey Power and Light Company (NJP&L). Ownership of the dam, impoundment (known as Columbia Lake), and surrounding property was subsequently transferred to the State of New Jersey and incorporated into the Columbia Wildlife Management Area in 1955. A small hydropower company, Great Bear Hydropower, Inc., leased the dam from the state to generate power in 1986 and it operated in a limited capacity until 2016. Over the decades, the 43-acre Columbia Lake accumulated sediments from upstream resulting in increased water temperatures and decreased dissolved oxygen levels. To improve aquatic connectivity in the Paulins Kill, the New Jersey Department of Environmental Protection (NJDEP), The Nature Conservancy (TNC), and the U.S. Fish and Wildlife Service (USFWS) collaborated on a project to remove the Columbia and Remnant Dams. The restoration effort began in June 2018 when the Remnant Dam was removed from the river, and the NJ Division of Fish and Wildlife began lowering the water level in Columbia Lake. About 2,000 fish were relocated from the impoundment into the Delaware River, and invasive species that were captured, such as common carp, were humanely destroyed. Downstream of the Columbia Dam, 976 freshwater mussels representing six species were salvaged and relocated to suitable habitats upstream of the impoundment and in the Delaware River. Additionally, eight mussels representing two species were relocated from the lowered impoundment. Weir structures were created under the Interstate 80 bridge to provide the depth and velocities needed for the passage of American shad. A passive sediment management approach was implemented to control the release of accumulated sediment from the impoundment. In August 2018, the first notch was cut into the dam and subsequent notches were cut as river conditions allowed over the following months. The last portion of the dam was removed from the river in January 2019 and three months later, American shad were observed upstream of the dam site for the first time in over 110 years. During the spring and summer of 2019, the river channel was stabilized in the former impoundment and the riparian areas were revegetated by planting native trees and shrubs. In addition to restoring passage for migratory fishes, this project improved water quality, reduced localized flooding, enhanced access for recreational fishing, and eliminated a public health and safety hazard. This project was primarily funded by the Natural Resource Damage settlement from the Combe Fill South Landfill Superfund Site, with TNC, the U.S. Department of Agriculture’s Natural Resource Conservation Service (USDA-NRCS), the USFWS Fish and Aquatic Conservation program, the NJ Corporate Wetlands Restoration Partnership (NJCWRP), and the National Fish and Wildlife Foundation (NFWF) funding the balance.

Restoration Land Ownership


Parties Implementing Restoration

New Jersey Department of Environmental Protection; The Nature Conservancy

DOI Project Representatives

Fish and Wildlife Service

The Columbia Dam and powerhouse were constructed in 1909 to generate hydropower for the surrounding communities., Credit: New Jersey Division of Fish and Wildlife

The Columbia Dam was removed in January 2019, allowing anadromous species access to approximately 11 miles of the Paulins Kill and 22 miles of tributary streams., Credit: New Jersey Division of Fish and Wildlife

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Restoration Documents

Document NameDocument Date
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Map View

Additional Resources

A Tale of Two Fishes: Removing the Columbia Dam (The Nature Conservancy)

YouTube: Columbia Lake Dam Removal on the Paulins Kill in New Jersey (The Nature Conservancy)

YouTube: Columbia Dam Removal Project: Removal of the Columbia Dam (USFWS)

YouTube: Columbia Dam Removal Project: Construction of Fish Passage Structures (USFWS)

YouTube: Columbia Dam Removal Project: Removal of the Remnant Dam (USFWS)


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