Why Riverkeeper supports the plan to remove Tillson Lake Dam

Tillson Lake (photo by Lauren Thomas)

Over its 52-year history, Riverkeeper has worked to protect both the Hudson Valley’s environment and its communities. We care about healthy rivers, safe drinking water and having vibrant places to live and great parklands to enjoy. In the case of Tillson Lake Dam, we support the removal plan being advanced by the dam’s owners, the State Parks system and the Palisades Interstate Park, and we are motivated by concerns for human safety, biodiversity and fiscal prudence alike.

We do not stake our claim lightly here, nor do we seek the removal of all dams, especially ones that involve critical human infrastructure or have high recreational value. From the moment we stepped into the Tillson Lake Dam debate, we have been willing to discuss our position and have, as promised, initiated plans to discuss the issue with the local community, with the gracious assistance of the office of Assemblyman Kevin A. Cahill.

It’s important to remember how severe the risk posed by Tillson Lake Dam is. There are some 1,500 dams in the Hudson Valley, including 93 “Class C” high hazard dams posing a danger to human safety. The Tillson Lake Dam is one of those high hazard dams, and it failed a recent safety inspection. The spillway of the dam is crumbling and it’s also too small for the impoundment, meaning that heavy rains put the dam at risk for failure. Due to similar problems in the past, the dam has already failed twice since it was built in 1930. Now, instead of a loss of farm equipment and livestock, a breach could be catastrophic, seriously jeopardizing human life and property.

Before it was acquired by Minnewaska State Park, the previous owner of the Tillson Lake Dam was forced to rebuild it in 1983 when it failed to pass a safety inspection. The lake behind the dam was not filled until the dam was rebuilt again in 1995. Now, 23 years later, the renewed risk of failure means that Tillson Lake Dam would again need to rebuilt if it is to remain in place, but this time at taxpayer expense.

The park officials in charge of Tillson Lake Dam have decided not to spend the nearly $9 million it would cost to restore the dam, proposing, instead, removal and re-establishment of the Palmaghatt Kill as a free-flowing stream, which would cost $8 million less than dam reconstruction. Removing the Tillson Lake Dam would not only save $8 million in construction expense, it would eliminate ongoing maintenance costs, reduce flood risks and improve the natural habitat and biodiversity within Minnewaska State Park.


In deciding what to do about Tillson Lake Dam, it’s important to take a step back and look at the impacts dams have on our waterways. In general, dams fragment our rivers by blocking their natural flow, prevent fish from reaching critical spawning and feeding habitats and keep sediments from moving downstream where they’re needed to prevent erosion and maintain water quality. Dams also alter the chemistry and temperature of our rivers, making them less habitable for native species like wild brook trout and freshwater mussels, which are specifically adapted to our rivers’ natural conditions. Here in the Hudson Valley, river herring and shad populations have declined by 95 percent, with native strains of trout and other species also in steep decline.

Above the Tillson Lake Dam, the Palmaghatt Kill takes its waters from the wild, uninhabited landscape known as the Awosting Reserve. If the dam were removed, the Awosting Reserve would provide a sufficient volume of high-quality headwaters to restore the Palmaghatt to consistent levels of flow and re-establish great recreational fishing opportunities, prompting the Catskill Mountains chapter of Trout Unlimited to join Riverkeeper in supporting the Palisades Interstate Parks Commission’s dam removal plan.

Since its origins, Riverkeeper has practiced environmental activism in defense of the Hudson River and its tributaries, even when that action was viewed as controversial. Considering the safety risks posed by the Tillson Lake Dam, the costs associated with restoring it, and the improved environmental conditions its removal would create, we feel our position here is soundly grounded and we look forward to a healthy and positive debate with all those who hold a stake in this important matter.

The writer is the president of Riverkeeper, an environmental organization dedicated to protecting the Hudson River and its watershed.


There is one comment

  1. Mark Rehnborg

    I find it disheartening that the State is now dictating the fate of Tilson lake with little local input when the property was handed over to it as a consequence of a civil lawsuit involving the owners of Awosting Reserve. In that decision, the State was handed more than 2500 acres of land that we now think of as part of the protected Shawagunk Ridge, and only because it was part of the same property section, block and lot number, did Tilson Lake end up in the State’s domain. At that moment, the Tilson Lake community finally took a breath after years of fighting with John Bradley, the owner at that time, over the use of the property. But now again, they have to fight for it; they have to fight for something that’s been in their back yard, and in their culture for many decades longer than the State has owned it.

    The argument that removing the dam will restore the natural habitat is understandable, but weak. The dam has been there for so long that the previous habitat is long gone, and given all the other development in that time frame, both upstream and downstream, it will never return. The habitat that’s there now IS the habitat, and removing the dam will destroy it as badly as creating the damn destroyed the previous habitat in the first place.

    Tilson Lake has been a recreational area for more than 100 years. It has been a day camp, an amusement park, a fishing and swimming hole, and a social destination through the decades. Though its commercial viability faded many years ago, it still remains a sanctuary for not only it’s local residents, but so many who enjoy it from all over the Mid Hudson Valley.

    Should the state and the taxpayers pay for the dam repairs? If they fund projects like this throughout the state, then damn straight they should. But if they really don’t want the property as it was given to them [for free, no less], then the State could offer a partnership with the Town of Gardiner, and possibly the Town of Shawangunk, to develop, preserve, and fund the property. That would at least put the fate of Tilson Lake more closely in the hands of the people who care about it.

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