PPL Holtwood

Recreational, Environmental & Historical Enhancement

Bald Eagle Management and Monitoring Plan


To protect two pairs of nesting bald eagles located within 2,600 feet of construction at the Holtwood hydropower facility PPL Holtwood partnered with the U.S. Fish and Wildlife Service and Pennsylvania Game Commission to develop a site-specific adaptive management plan.  This plan includes seasonal construction restrictions, phased construction activities and monitoring studies at the nests during blasting. Results from these studies have produced new knowledge about the tolerance of bald eagles to construction activities. This information will assist regulators, consultants and licensees in understanding how to protect the iconic symbol of the U.S. and how to develop reasonable solutions to avoid disturbing eagles during construction.


PPL Holtwood, LLC (PPL) owns and operates the Holtwood Hydroelectric Project (Project) on the lower Susquehanna River in Lancaster County, PA.  This project is currently about one-third the size of the hydroelectric projects immediately upstream and downstream.  As a result, PPL has licensed and started redeveloping the Project by adding an additional 125 MW of power to the existing 100 year old 107 MW powerhouse.  The expansion project requires excavation to expand the forebay and construction of a new skimmer wall above the dam.  It also includes construction of a new powerhouse adjacent to the existing one as well as excavation of several areas below the dam to allow water to pass downstream without creating backpressure on the generating units, while simultaneously creating an enhanced route for anadromous fish passage.  Additionally, PPL is installing a draft tube extension to an existing unit that will divert water through a diversion wall into an existing river channel, known as Piney Channel, for an enhanced secondary migratory fish passage route.  Other project improvements include fishing access downstream of the powerhouses, creation of whitewater boating features, and enhancements to existing boating access points on the Project reservoir.  PPL’s goal is to complete these projects in time to have the new powerhouse station operational by the end of 2013.

Two pairs of nesting bald eagles live within 2640 feet of the construction project.  The United States Fish and Wildlife Service (Service) protected the bald eagle under the Endangered Species Act until 2007.  Currently, the Service protects the bald eagle under the Bald and Golden Eagle Protection Act and Migratory Bird Treaty Act.  The bald eagle is a threatened species in Pennsylvania and the Pennsylvania Game Commission (PGC) is the state agency that regulates the protection of bald eagle in the state. The Service uses the National Bald Eagle Management Guidelines (Guidelines) to provide guidance to landowners regarding how to protect bald eagle from disturbance and prevent violations of these regulations.  PPL consulted with the Service and PGC under the FERC licensing process for their Holtwood Hydroelectric Redevelopment to develop a site specific plan that would allow PPL to complete their project and prevent disturbance of bald eagles.  PPL produced the Holtwood Redevelopment Bald Eagle Management and Monitoring Plan (Plan) using the Guidelines but adapted the guidance using existing scientific knowledge of the tolerances of bald eagle to construction related impacts. PPL recognized that the Guidelines were general and PPL could improve the scientific understanding through monitoring bald eagle activities during the Holtwood Redevelopment.


From 2009 to 2012, PPL faced the difficult challenge of balancing the efficient redevelopment of the Holtwood Project with the sensitivity of two nesting bald eagles within 2640 feet of the construction site.  As written, the Guidelines prevent blasting within 2640 feet of a bald eagle nest during the nesting season.  In this region, the nesting season lasts from approximately December to the end of June.  This only provided PPL with 22 weeks each year when their contractor could blast and complete 1.8 million cubic yards of excavation within this 2640 foot protection zone.  PPL completed a literature review and hired experts to analyze the existing knowledge of the effects of construction activities, in particular blasting, on bald eagle nesting and foraging.  PPL’s research found that specific studies regarding the effects of construction activities, including blasting, were not available for bald eagle.  PPL was able to evaluate the potential effects of blasting and construction activities based on studies from related species or other similar human activities near bald eagle nests. The Service and PGC agreed with PPL’s research and decided that restricting construction activities and blasting to a certain distance away from the bald eagle nests would not necessarily protect the bald eagles.  Instead, the Service, PGC, and PPL determined that regulation of the noise or ground vibrations would be a better measure for minimizing the effects of the construction activities on the nesting bald eagle.

Through this consultation with the Service and PGC, PPL developed the Plan using scientific research to adapt the standard guidance provided in the Guidelines.  The Plan reduced the minimum distance of blasting activities from 2640 feet down to 1320 feet from all eagle nests.  PPL protected the trees within 330 feet of the bald eagle nests by redesigning excavation away from the land that the eagles were nesting.  PPL also did not allow construction activities within 660 feet of a bald eagle nest during the nesting season.  The Plan also required sequencing construction activities to limit the footprint of the project at any given time.  This allowed portions of the construction site to remain available to the eagles for feeding in nearby habitat without the threat of disturbance.  To assure that this plan was implemented and functioning as planned, PPL hired an ornithologist to monitor the construction site during the eagle nesting season and observe the nesting behavior of the eagles during blasting.

The challenge became even more difficult with the construction delays caused by flooding from Hurricane Irene and Tropical Storm Lee in 2011.  In order to make up for losing 15 weeks of excavation season during 2011, PPL needed to modify the Plan to allow excavation within previously restricted zones during the bald eagle nesting season. The most significant modification involved reducing the blasting restriction from 1320 feet away from the eagle nests to 660 feet.  Fortunately, PPL had two years of experience monitoring the bald eagles and managing construction activities to protect the bald eagles.  This experience provided PPL with the information needed to collaborate with the Service and PGC to modify the Plan and allow the excavation to get back on schedule and still endeavor to protect the nesting bald eagle during 2012. The Service and PGC issued a Federal Fish and Wildlife Permit (Permit) in January 2012 that would allow PPL to make these modifications to the Plan.


The primary concern of the Service and PGC was the effect of blasting noise on eagle nesting activities.  Therefore, PPL designed the monitoring in the Plan to focus on whether or not blasting noise would affect eagle nesting activities.  PPL monitored the closest nest to the construction activities because this nest would have the most potential for disturbance by construction activities.  To complete the monitoring, PPL installed a 120-foot tower and mounted video and audio monitoring equipment on the tower to observe the eagles during the nesting season.  This tower contains two remotely operated cameras, a decibel meter with pre-amp, and a seismograph to complete all necessary monitoring for the duration of construction.

To minimize the potential for disturbing the nesting bald eagles during research, PPL designed the monitoring equipment to be autonomous during the eagle nesting season. A solar power and battery storage system power the electronics on the tower.  Scientists can control the cameras and sound meter by radio signals from the Holtwood Powerhouse.  All video, audio, and seismic data is transmitted to offsite computers for data storage and review.

Scientists monitored and recorded the live video feed 30 minutes before and after a scheduled detonation of a blasting charge.  A trained ornithologist reviewed the video for observed bald eagle behavior before and after detonation to detect changes in behavior.  In addition, the scientists measured sound by recording peak decibels and A-weighted decibels.  Scientists used all recorded decibel data to monitor noise from redevelopment activities, and determine if these noises correlate to eagle behavior.  PPL also included seismic monitoring at the eagle monitoring tower to determine how ground vibrations may also be contributing to eagle reactions to blasting.

Another related study that was included in the Permit was a Global Positioning System (GPS) telemetry study that monitored the activities of two juvenile bald eagles fledged from one of the nearby bald eagles nests.  The GPS telemetry study would provide information on how juvenile bald eagles use foraging habitat in the presence of nearby construction activities.  Future data produced by the GPS telemetry equipment may also show if these juvenile eagles return to the area for feeding or potentially nesting.


From 2009-2011, PPL successfully completed the excavation required for Piney Channel, Unit One Diversion, and the Powerhouse.  PPL monitored two nesting seasons and observed that the bald eagle nest successfully produced a total of three young from 2009-2011.  After changes were made to the Plan in 2012, PPL pioneered the research regarding the effects of construction activities, in particular blasting, on nesting bald eagle.

During the 2012 nesting season, PPL recorded the responses of bald eagle during 147 blasts. From these blasts, the bald eagles responded to the stimuli of the blasts only 10 times.  The eagles at the observation nest did not successfully nest in 2012.  This was likely caused by a combination of factors including nearby construction activities and increased competition from a new collection of great blue heron nests that were active adjacent to the eagle nest in 2012.  The construction activity may have disrupted the daily routine of the bald eagle, leaving the nest susceptible to predation by the neighboring heron.

PPL is still studying the results from these studies; however, the research has shown that higher decibels and seismic activity caused responses from the bald eagle.  PPL was able to successfully blast less than 2640 feet from a bald eagle nest and the majority of the blasts did not cause a reaction from the bald eagles.  PPL has demonstrated that contractors can adjust blasting techniques to minimize the effect of noise and seismic activity on bald eagle.  PPL plans to further analyze the results from this study at the completion of the redevelopment and make the information available to the public through publication in a peer reviewed scientific journal.

Once the bald eagles completed nesting activities, PPL was able to resume construction activities with few restrictions because the construction did not disturb bald eagles that were foraging in the construction site.  PPL regularly observed that adult and juvenile bald eagles continued to find food in the waters within and around the construction activities.  The GPS telemetry study in 2012 demonstrated that juvenile bald eagle chicks behaved normally, even in the presence of nearby construction activities.  The two bald eagles the researchers tracked with GPS telemetry equipment spent the majority of their time in Piney Channel, a fish passage channel enhanced by PPL to create fish habitat and feeding opportunities for wildlife.  As the eagles became strong enough to fly longer distances the two young eagles joined other bald eagles at well-known feeding locations in the Chesapeake Bay.

PPL’s Plan was unique because it provided a mechanism to provide site-specific studies while minimizing the effects of the on-going construction activities on the bald eagles.  The monitoring studies provided the science that was required to allow PPL to complete a large amount of excavation in an environmentally sensitive location.  Working with the Service and PGC, PPL demonstrated that a cooperative relationship with the regulators provides mutual benefits.  The research from this Project will provide regulators and scientists access to the methods from PPL’s Plan that could advance similar research with other protected species, as well as provide regulators and conservationists with management practices for the protection of other bald eagle nests.  PPL’s efforts have maintained high standards for environmental stewardship and successfully completed construction tasks.