By Olivia Matise

Gowanus Canal in Brooklyn, New York, is generally not considered a destination for a scenic stroll along its esplanade. Once a system of marshes and streams inhabited by the Lenape people, the area was forcefully dispossessed by European colonizers who then subjected the ecosystem to centuries of dredging, damming and infilling.

Today, this once sprawling network of wetlands has become just one; the Gowanus Canal.

In the 1800s, Brooklyn was the fastest growing city in America, making the Gowanus Canal one of the nation’s busiest waterways. The industrialization of the Gowanus marshes and the New York Harbor decimated their once-thriving oyster beds, and left a toxic sludge that still covers the bottom of the Gowanus Canal, known as “Black Mayonnaise.”

Industrial pollution from gas plants, coal yards, and factories — as well as Combined Sewage Overflow (CSO) from the surrounding sewer shed (land drained by sewer systems) — has led to a push for remediation of the canal’s shorelines and water quality over the past 30 years. In 2010, the canal was designated a Superfund site by the EPA and placed on the National Priorities list. The Superfund designation led to a final plan to dredge about 10 feet of contaminated sediment from the bottom of the canal and construct two water tanks to address CSO.

Negotiating and funding the clean-up project has been a long and bureaucratic process. The City of New York is obligated to create the sewage filtering facility by 2028 — a deadline that was tested when dredging was delayed until 2017. Furthermore, combined costs of the dredging project and tank construction totals around $3 billion, split between the City and the EPA.

Today, the initial stage of the dredging is complete; as of October 2021, 35,000 cubic yards of sediment have been removed and much of it processed to be recycled as landfill cover. The canal will continue to be dredged in segments, designated Remediation Target Areas, which will be treated differently depending on their levels of contamination.

A toxic sludge covers the bottom of the Gowanus Canal, known as “Black Mayonnaise.”

In addition to the dredging, highly contaminated areas of the canal floor will be capped using a process called In-Situ Stabilization. The process involves injecting the bottom of the canal with chemical compounds like concrete to keep the contaminated areas from spreading through the canal. These areas will then be covered with a multilayer “cap” consisting of clay (the “active” layer) to absorb contaminated particles, sand and gravel (the “isolation” layer) to prevent the first layer from exposure, and stone topped with sand (the “armor” layers) to prevent erosion and restore the canal floor to a healthy marine habitat.

SOURCE: Star Revue

Total restoration of the canal will depend on preventing contamination from upland sources, which the City is responsible for regulating.

The push for cleaner waters comes from stakeholders invested in community development initiatives such as affordable housing and recreation surrounding the Gowanus Canal Esplanade.

The Gowanus Dredgers Canoe Club has played an integral role cleaning up the site, and has advocated for its revival for over 20 years. The Gowanus Canal Conservancy is a grassroots organization that promotes ecologically sustainable development around the Gowanus watershed through community engagement and education. After the canal was designated a Superfund site, the Gowanus Canal Community Advisory Group was formed. Made up of over 50 scientists, business, civic, and community organizations, it remains the largest Community Advisory Group for an EPA Superfund site in the country.

In 2010, the canal was designated as a Superfund site by the EPA and placed on the National Priorities list.

The Brooklyn Atlantis Team, a group of researchers from the department of Mechanical and Aerospace Engineering at NYU Polytechnic Institute, has been using citizen science and robotic boats to monitor and record data about water quality in the Gowanus Canal. Their project will help the EPA monitor the ecological health of the canal, creating an index of photo imagery data.

The Gowanus community continues to fight for equitable and environmentally sensitive development that will someday restore the canal to the beauty and function of its pre-colonial days.

Map of Brooklyn, NY made in 1766

Gowanus Canal History

As the need for navigational and docking facilities in the burgeoning port of New York City grew, in 1849 the New York State Legislature authorized the construction of the Gowanus Canal (completed in the late 1860s). Despite its relatively short two-mile length, the Gowanus Canal soon became a hub of Brooklyn’s maritime and commercial activity. Factories and residential communities sprang up because of its construction. In fact, much of the brownstone quarried in New Jersey and the upper Hudson were placed on barges and shipped through the canal to create what we now refer to as “Brownstone Brooklyn”.

Want to learn more or get involved? Check out these resources!

To check the status of the Gowanus Superfund site, click here!

Visit the Community Advisory Group website to keep track of events and meetings!

Check out the Gowanus Canal Conservancy ‘Get Involved’ page to find volunteer opportunities!


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