The following is from the Palisades Interstate Park Commission (PIPC) agenda for its April 16, 2018 meeting:
Based upon engineering assessments and reviews by the New York State Department of Environmental Conservation's Dam Safety Unit, the Tillson Lake Dam has several issues that require corrective action to ensure the long-term stability and safety of the structure, most particularly under significant rain events.
The Tillson Lake Dam is currently classified as a Class C (high hazard) structure, which is a standard rating term applied to all dams that have a certain amount of development downstream, but is not an indication of a dam's structural integrity or safety. All Class C dams must meet a high standard of structural integrity and have the ability to safely pass water without failure under specific flood conditions.
Given the dam's current design and condition, it no longer meets the dam safety requirements that have been established for Class C dams. Because these requirements are so stringent, the projected costs to bring this dam into compliance could be as high as seven to nine million dollars. The Commission has been unable to secure funding for the required renovation that would bring the dam into compliance. As a result, and in order to ensure the long-term safety of the downstream properties and improvements that could be threatened by a potential failure of the dam, the Commission is taking steps to design and seek approval for the removal of the dam and restoration of the lake back to a natural stream corridor.
In the coming months, Staff will be revising the Minnewaska State Park Preserve Master Plan as it pertains to Tillson Lake and proceed with the permit process for the dam removal, so as to ensure the long-term safety of those properties and improvements that would be impacted in the event the dam is compromised and to provide for the reestablishment of a natural stream corridor that is environmentally sound.
(Item posted April 3, 2018)