Hydropower is derived from the force of moving water. Electricity is produced when falling water at dams rotates turbines. Despite their lack of air pollutants, large hydropower projects do disrupt the natural flow of rivers and can have a significant impact on landscapes and ecosystems.

In New York, State-owned hydropower is counted in the baseline of existing renewable energy resources, and new capacity at existing dams or new low-impact, run-of-river projects are eligible for Tier 1 of the Clean Energy Standard. Imports of hydropower can also count in both the baseline of existing resources and in Tier 1. Hydropower is clean and carbon-free, and is helping New York achieve its clean energy goals.

With improvements in technology, today's smaller hydro projects can be designed to minimize harm to fish and wildlife populations. Hydroelectric plants that do not require reservoir capacity, called low impact or run-of-river, are much preferred by environmentalists due to their reduced impact on natural landscapes.

A tidal power plant, which makes use of the daily rise and fall of tides, is another alternative to large-scale hydropower and is very effective due to its high predictability. A less common technology is kinetic hydropower, which can generate electricity by converting the energy found in the flowing water currents of oceans, tides, or rivers.  Neither tidal and kinetic hydropower are widely deployed.

Hydropower technologies are familiar in New York State, with their use dating back over 100 years. Today, about 19% of the electricity produced here comes from the hydropower facilities located at Niagara Falls, on the St. Lawrence River, and elsewhere. This legacy provides New York with an excellent base of pollution-free renewable energy, as well as resource diversity.