In 2019, New Jersey completed the removal of the old Columbia Dam and reopened about 14 km of river; a 2026 study found juvenile eels, sea lampreys and American shad upstream after years of monitoring

NewsWorld NewsUS NewsIn 2019, New Jersey completed the removal of the old Columbia Dam and reopened about 14 km of river; a 2026 study found juvenile eels, sea lampreys and American shad upstream after years of monitoring In 2019, New Jersey completed the removal of the old Columbia Dam and reopened about 14 km of river; a 2026 study found juvenile eels, sea lampreys and American shad upstream after years of monitoring TOI Lifestyle Desk / TIMESOFINDIA.COM / Oct 28, 2026, 02:57 IST Restored Paulinskill River (source: dep.nj.gov official site ) ">AI representation of the demolition of Columbia Dam (Canva Ai) Built in the early 1900s by the Paulins Kill Consolidated Ice and Power Company, the dam created a pond that could supply water for the ice industry and generate energy for nearby communities, including Columbia in New Jersey and Stroudsburg in Pennsylvania.

Over time, however, the structure became an obstacle for migratory fish that need to travel upstream to their breeding grounds to reproduce.Dams are well known to alter the natural flow of a river, affect water temperature and oxygen levels, interfere with sediment movement and prevent aquatic species from reaching suitable habitats.

For fish that migrate between freshwater rivers and the sea, these barriers can be particularly challenging because reaching upstream areas may be essential for reproduction or access to suitable feeding grounds. As a result, the Columbia Dam was considered a priority for removal because of its location near the Paulins Kill's confluence with the Delaware River, a historically important route for migratory fish.The upstream flow of the lost fish The health of fish populations within a river system, particularly migratory species, is a common indicator of river health.

After the dam's removal in 2019, the 2026 study documented encouraging signs among several migratory species that had previously faced a barrier at the dam.Researchers recorded higher densities of juvenile American eels upstream of the former dam site, along with adult sea lampreys and their larvae.

These findings suggest that migratory fish are once again accessing parts of the river that were previously difficult to reach.American eels have a particularly interesting journey, as they hatch in the Atlantic Ocean before their young travel towards freshwater rivers and streams, where they can spend years growing.

The presence of juvenile eels upstream is therefore an encouraging sign that they can now reach habitats that were previously difficult to access because of the dam.Along with eels, sea lampreys also migrate through river systems, and their reproduction involves building nests in riverbeds where they lay their eggs.

The study's findings of adults, larvae and nests upstream suggest that the restored river reach is being used for more than simply passage through the area.American shad, meanwhile, are migratory fish that travel from the ocean into freshwater rivers to reproduce.

The presence of adult shad upstream adds to the evidence that removing the dam has helped reconnect habitats that were previously difficult for migratory fish to reach.Did removing the dam improve water quality? You use AI every day.

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