Next Phase of Schoharie Reservoir Release Works
A micro-tunneling machine was lowered 182 feet down a shaft to begin work on more than 2,000 feet of subsurface tunnels. Once it begins tunneling, the machine is expected to excavate about 20–40 feet per day. The tunnels are part of a $142 million project that will provide DEP with the ability to release water from the reservoir into Schoharie Creek to facilitate dam maintenance, respond to potential emergencies, mitigate flood risk for downstream communities, and enhance downstream habitat for fish and wildlife.
The release works are one component of a larger $400 million program aimed at strengthening the 90-year-old Gilboa Dam and ensuring that Schoharie Reservoir continues to provide reliable, high-quality drinking water to New York City in the future. The program began with the full-scale rehabilitation of Gilboa Dam, a $138 million project that finished in 2014. It will also include upgrades to the Shandaken Tunnel Intake Chamber and site restoration work. DEP implemented the program of repairs and upgrades at Schoharie Reservoir more than a decade ago to achieve modern dam safety standards at Gilboa Dam. The release works are expected to be completed in the year 2020.
The unmanned micro-tunneling machine will be operated by remote control from the surface. The machine will drive two tunnel sections that total 2,118 feet, running as deep as 185 feet below the surface. The first leg of the tunnel will stretch 1,188 feet from the gate shaft to a valve chamber on the eastern bank of Schoharie Creek. The valve chamber will be located about 1,000 feet downstream of Gilboa Dam. A second leg of the tunnel, stretching 930 feet, will run from the gate shaft to the intake structure at the bottom of Schoharie Reservoir, several hundred feet south of the dam. Once workers bore into the bottom of the reservoir, a specialized dive team will remove the micro-tunneling machine from the 135-foot-deep water and install the remaining parts of the intake structure. The construction of both tunnel sections is expected to take six months.
The valve chamber — which acts as the portal that releases water into the creek — will include two valves capable of releasing about 65–1,550 million gallons of water each day. A third, smaller valve will be capable of smaller releases up to 65 million gallons per day.
Releasing water from Schoharie Reservoir will support multiple goals related to reservoir operations, public safety and conservation. The release works will provide DEP with the capability to draw down the reservoir for periodic maintenance and in response to potential emergencies. The release tunnel would also help DEP mitigate flood risk for downstream communities by releasing water to counterbalance snowpack in the Schoharie watershed.
New York City depends on Schoharie Reservoir to provide nearly 15 percent of its daily drinking water, and our neighbors downstream rely on its infrastructure for public safety.