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Committed to efficient water use

Access to water is essential to Exelon’s production of electricity which supplies power to the equivalent of more than 19.5 million homes in the United States.  We understand the importance of being responsible stewards of this critical resource, and we recognize the potential effects that climate change, increasing demand for water and more stringent regulations will have on our ability to access water resources in the future.

CDP Water Survey
In 2012, both Exelon and Constellation completed the Carbon Disclosure Project (CDP) Water Survey to provide transparency into our efforts to manage the use and risks associated with this important resource.   

Exelon CDP Water Response [PDF | 186 KB]
Constellation CDP Water Response [PDF | 124 KB]

Water Utilization

Exelon understands the importance of being responsible stewards of our water resources. With operations in a variety of geographic areas across the United States, we are focused on understanding the specific needs and sensitivities of the watersheds in which we operate and strive to incorporate its value into our business planning. In 2011, Exelon utilized about 43.6 billion gallons of water per day.  Constellation facilities utilized nearly 1.38 billion gallons per day.  For both companies, over 99% of the water used is for cooling in the electric generation process, returned to its source without the need for chemical treatment.   

As we continue to develop and expand our water conservation program, continued to work to maintain compliance with applicable regulations, support restoration and maintenance of native fish species, and broaden our commitment to reduce aquatic impacts.  As we continue to refine our business strategy, we are broadening our considerations to include the vital role that water resources play in achieving sustainable business growth and success.

Both Exelon and Constellation completed the 2012 Carbon Disclosure Project (CDP) Water Survey to provide transparency into our efforts to manage the use and risks associated with this important resource. 

Key Water Issues

The primary environmental issues associated with power plant cooling water systems are consumptive use of water, thermal discharge, and entrainment and impingement of aquatic organism.  In response to the growing effects of climate change, there are also impacts associated with changing water flows and temperature trends.  Exelon is monitoring watersheds to understand how these changes may impact the water resources with which we interact.  

Some of the sensitive watersheds that the company relies on are the Mississippi River; the Susquehanna River, which empties into the Chesapeake Bay; the Barnegat Bay in New Jersey; and the Delaware River.  Although the broad issues mentioned above are common to all these watersheds, the specific characteristics and regional nature of water resource regulation necessitates the strategic managment of water use locally at each operating site.  Some examples include:

  • Closed-cycle cooling water systems require adequate supplies of make-up water to replace that which is lost to evaporation.  At our Limerick nuclear plant, for example, we have developed an innovative approach for augmenting make-up water using water from abandoned coal mines.
  • In open-cycle cooling water systems, aquatic organisms can become entrained in the intake flow or become impinged on the intake screens. To address this condition, a variety of measures can be used, including reducing the flow velocity and using specially designed equipment that allows for the safe passage of organisms.
Conowingo and Muddy Run Relicensing
Exelon’s two hydroelectric power plants, Conowingo and Muddy Run currently hold licenses that expire in 2014.  In March 2011, Exelon Generation presented results from the first year of studies to agencies and stakeholders as part of the FERC integrated relicensing process (ILP).  The ILP creates the opportunity for agencies and stakeholders to provide feedback on these studies in order to determine if and what additional information would be required to pursue relicensing.  

Water Regulation

Thermal discharges are regulated under the Clean Water Act Section 316(a), and entrainment and impingement is being addressed under Section 316(b). In March 2011, the EPA issued a proposed rule addressing existing power plant cooling water intakes, and EPA is expected to issue a final rule in late 2012.  Exelon is actively engaged with the electric utility industry, which is advocating for specific regulatory outcomes that would achieve the most economical and effective reduction of environmental impacts.

Exelon continues to comply with the existing conditions of our National Pollutant Discharge Elimination System (NPDES) permits, while it is evaluating its affected facilities (Oyster Creek, Peach Bottom, Dresden, Quad Cities, Clinton, Eddystone, Cromby, Fairless Hills, Handley, Mountain Creek, and Schuylkill) to develop plans for cost-effectively meeting the proposed changes to the rule.

On Dec. 8, 2010, Exelon Generation announced that it will permanently cease generation operations at Oyster Creek Generating Station by Dec. 31, 2019. This decision was made because the installation of cooling towers, as proposed by the New Jersey Department of Environmental Protection (NJDEP), would render the plant uneconomical. As a result of our decision to retire the plant early, the NJDEP determined that existing measures at Oyster Creek represent the best technology available for the facility’s cooling water intake to comply with Section 316(b) of the Clean Water Act through 2019.

Compliance Performance

Exelon has set a goal of zero water Notices of Violation (NOV) and Permit Noncompliances for company operations. In 2011, Exelon received two water related violations and Constellation received one water related violation.  NOVs are issued by a regulatory agency when a company is believed to have violated a permit condition or regulatory requirement.  Exelon self-reports violations of regulations and regulatory agency-specified environmental permit conditions when they are identified.

Exelon Corporation 2011 Sustainability Report |PDF 4.1 MBMore information on Exelon and Constellation's compliance performance can be found in the Managing Environmental Risks section of our 2011 Sustainability Report. PDFPDFs require software like the Adobe Acrobat Reader to be viewed properly.

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