Riverkeeper backs plan for removal of dam

Riverkeeper supports a plan to remove the dam that created Tillson Lake in the Minnewaska Park system.

GARDINER, N.Y. » Riverkeeper is supporting a Palisades Interstate Park Commission plan to remove the dam that created Tillson Lake in the Minnewaska Park system.

The position was outlined on the Riverkeeper website last week, with habitat restoration manager George Jackman stating the 88-year-old dam impedes the natural flow of the Palmaghatt Kill, which had created an environmentally important ravine.

“This is an ancient and wild ravine, where many hemlocks have been dated at well over 400 years old,” he wrote. “The Palmaghatt drains the lands of the Awosting Reserve and then, shortly after, hits a wall: The dam holding back and controlling its water in man-made Tillson Lake.”

Jackman added that blocking the flow of the creek interferes with fish behavior during the summer.

“The downstream ecology becomes further disrupted, and temperature-sensitive fishes such as trout and other native fishes as well as aquatic invertebrates, which prefer cooler waters, are no longer supported,” he wrote.

“From a philosophical perspective, it is a corruption of nature to deprive rivers of their natural flow of water and seasonal distribution cycles,” Jackman wrote. “Under normal flow regimes, water is delivered to the landscape in pulses, wherein many forms of aquatic organisms have programmed their life-stages with exacting precision to very specific temporal and spatial ranges, which depend upon unaltered and unimpeded access to seasonal water flows.”

Palisades Interstate Park Commission officials have proposed to decommission the dam due to an absence of funding for $8.55 million in repairs needed to avoid a catastrophic failure.

Commission Executive Director James Hall last month told the Freeman that decommissioning the dam will cost about $1 million for engineering studies.

“It’s had its inspections through (the state Department of Environmental Conservation) and you also have to do an engineering assessment on the structure as part of being in compliance,” Hall said. “It outlined several issues that the structure has aside from the spillway capacity being way undersized. It also has some ongoing structural issues with the splash pad for the spillway kind of falling apart and it’s got some seepage along the lower portion of the dam.”

Opposition to the plan has come from residents near the dam. They have formed Save Tillson Lake as part of efforts to interest elected officials in funding repairs.

“We are formulating a plan,” organization co-chairman Morey Gottesman said. “We’re contacting all our elected representatives ... and we intend to stay active and contact various environmental groups to see where money can be found.”

An engineering study reports the dam was constructed in 1930 to provide a recreation area for the surrounding communities and has been reconstructed following failures in 1938 and 1955. It is about 39 feet tall and 308 feet long, which creates a lake covering 23 acres.

Officials wrote that the breach on Sept. 21, 1938, caused a “tremendous amount of erosion to farmland, loss of farm machinery, chickens, several local bridges and basement flooding.”

Information was not immediately available on whether there was damage from the breach in August 1955.

The lake had also been drained on July 2, 1983, when a “maintenance worker who opened the sluice gate to lower the pool elevation ... subsequently forgot to close the valve. An extensive rehabilitation project commenced in 1984, however, the lake remained unfilled until 1995.”