Cannonsville Reservoir dam

New York City Department of Environmental Protection The dam at the Cannonsville Reservoir is seen in this 2014 photo.

The New York City Department of Environmental Protection has announced plans to build a $34 million hydroelectric plant at the Cannonsville Reservoir.

According to a media release, the 6-megawatt facility will generate enough renewable electricity to power more than 3,500 homes annually by harnessing the force of water  released downstream of the reservoir at its dam in Deposit. The DEP said it expects to complete the 4,400-square-foot hydroelectric facility by 2025.

The revised proposal follows a 2015 engineering assessment at the site, which found an artesian aquifer downstream of the dam. Initial plans for a 14-megawatt facility, including a 9,000-square-foot powerhouse, were "deemed infeasible after the initial examination of conditions at the site," the release said. The DEP has worked with experts since that time to develop a revised plan for generating clean energy at the site.

DCAS is responsible for purchasing all the energy required to run New York City’s government, and for managing its energy use. It will provide $9.8 million for the design and $7 million toward the construction of the hydroelectric plant at Deposit, the release said.

The DEP will host two public meetings on Dec. 14 to share additional information and answer questions about the new plans. Those meetings will be held at the following locations and times:

• 9 a.m. at the Deposit State Theater, 148 Front St., Deposit;

• 12:30 p.m. at the Upper Delaware Council office, 211 Bridge St., Narrowsburg.

The proposed plant will include two 3-megawatt generators inside a 4,400-square-foot powerhouse adjacent to the West Delaware Release Chamber. The turbines will generate an estimated 32,000 megawatt hours of electricity each year. Electricity produced at the plant will be introduced into the grid through a new substation that will be built several hundred yards downstream of the dam.

According to the release, the project "will create dozens of construction jobs, several full-time jobs to operate the finished plant, and it will generate hundreds of thousands of dollars in new property tax revenue."

During a 2015 geotechnical assessment to support the foundation design for the larger powerhouse, DEP contractors found that an artesian aquifer — a naturally pressurized pocket of groundwater — was present downstream of Cannonsville Dam. The DEP engineers and contractors performed work to reduce the condition by installing relief wells and used a special grouting technique to shut the boreholes that tapped into the aquifer. 

The DEP notified officials at the Federal Energy Regulatory Commission this week that it will no longer pursue the original project. The smaller, revised hydroelectric plant may qualify for a license exemption from FERC because it is less than 10 megawatts.