A Longtime Power Source That's Environmentally Friendly 

Hydroelectric energy, one of the oldest power sources on the planet, generates electricity when flowing water spins a wheel or turbine. It’s a renewable energy source and produces no carbon, greenhouse gases, or toxic byproducts.

When most people think of hydro, they think of the Hoover Dam, a massive wall that harnesses the power of a river. But hydroelectric facilities can also be quite low profile. In fact, almost every state in the nation uses hydroelectricity.

Constellation owns and operates two hydroelectric power plants along the Susquehanna River in Maryland and Pennsylvania. Conowingo Hydroelectric Generating Station and Muddy Run Pumped Storage Facility provide more than 1,600 megawatts of low-carbon power generation, as well as much needed load-leveling and 24/7 baseload power.


Conowingo Hydroelectric Generating Station is Maryland’s largest source of renewable electricity, producing more clean energy than all other sources combined. Unlike intermittent wind and solar generation, Conowingo’s power is 24/7 and can respond to changes in demand and supply extra energy to the grid within 10 minutes. If there is a large-scale blackout, Conowingo is the first power plant called on to restart the regional electric grid.

The Conowingo power plant produces 1.6 million megawatt hours (MWh) of electricity annually, enough to power more than 159,000 homes for a year.  It also prevents 758,000 tons of greenhouse gas emissions (GHG), the equivalent to taking 150,000 cars off the road.

Learn more about Conowingo. 

Muddy Run Pumped Storage Facility is a hydroelectric power plant located on the Susquehanna River that has provided electric power to the regional transmission system since 1966. The plant’s eight units can generate 1,070 megawatts (MW) of clean electricity, output that is vital to meeting the demands on the area’s regional power grid.

To generate electricity, water in the upper reservoir at Muddy Run is used to fuel the turbines, then flows into the Susquehanna River. At night, electricity demand decreases so the units are reversed and used as pumps to fill the upper reservoir for use as fuel during subsequent peak-demand periods.

Learn more about Muddy Run. 

We support local communities and causes with charitable giving and sponsorships – typically driven by our employees. In 2020, Constellation contributed $5.6 million to 709 organizations in 2020, and our employees donated an additional $5.2 million and committed 52,885 volunteer hours across 34 states.

Learn more about Constellation’s commitment to our communities. 

All Generation facilities employ sophisticated emergency response plans to protect public health and safety. Plans are reviewed and approved by state governments and federal regulatory agencies. Emergency planning includes coordination with local and municipal officials as well as thousands of volunteers and first responders.

To protect the safety and health of our employees, contractors, customers and communities, we’ve implemented a number of initiatives to promote safe behaviors both on and off the job. These include a safety behavior observation program and focused initiatives on areas of high risk. We also offer safety training, which is integrated with leadership development programs for supervisors and managers, as well as new employee orientation. And the safety peer group identifies successful pilot programs or new practices that can then be adopted by the entire organization.