Project Overview


When operating licenses for non-federal hydropower dams expire, dam owners must apply to the Federal Energy Regulatory Commission (FERC) for a new license.  The license applicants, regulatory agencies, citizens, and non-governmental organizations (NGOs) participate in the FERC relicensing process to ensure new operating licenses reflect current environmental standards and addresses current public values.  As a part of the licensing process, dam owners must conduct resource studies to determine how their project affects public resources, and how various new operational schemes may benefit or harm these resources.  The Hydropower Reform Coalition (HRC) has commissioned this report to identify typical effects of hydroelectric projects on the environment, and evaluate the scientific approaches available to determine the effects.  It is hoped that this report will elevate and press forward the state of relicensing science, make it more consistent from project to project, and provide scientific assistance to the HRC consortium of more than 130 conservation and recreation organizations.  It is HRC’s intention that all hydropower licensing participants, including activists, state and federal resource agencies, tribes, dam owners, and FERC, will find this guide a valuable resource.


Hydroelectric projects potentially affect the environment by disturbing habitats, and by altering basic hydrological and fluvial geomorphic processes.  The alteration of chemical, biological, and physical processes can have consequent positive or negative effects on water quality, fish and other aquatic species, plants, terrestrial wildlife, recreation, aesthetics, and cultural resources.  The process of relicensing hydroelectric projects, as regulated by the FERC, provides an opportunity to consider these impacts.  Under 18 CFR § 16.6(b), an existing license holder is required to notify the FERC of its intention to file or not to file an application for a new license for its project before the license expires.  An application must be filed three years after notifying FERC of its intention to file an application for a new license.  Typically studies are conducted during that period, pursuant to applicant-prepared study plans.  The licensee drafts, amends, finalizes, and implements the study plan in consultation with agencies and other participants.  It is during this phase that relicensing participants have the opportunity to influence the types of environmental effects considered, and the approaches used to evaluate effects.  There are no specific requirements regarding the number or types of studies in a study plan.  A study plan supplements existing information to complete the exhibits required in a license application and environmental documents.  Further, it is the information gathered during relicensing studies that typically informs management actions described in the new license.  As specified by CFR 18, § 5.9(b) of FERC’s regulations under the Integrated Licensing Process (ILP), any study request must:

1.    Describe the goals and objectives of each study proposal and the information to be obtained;

2.    If applicable, explain the relevant resource management goals of the agencies or Indian tribe with jurisdiction over the resource to be studied;

3.    If the requester is not a resource agency, explain any relevant public interest considerations in regard to the proposed study;

4.    Describe existing information concerning the subject of the study proposal, and the need for additional information;

5.    Explain any nexus between project operations and effects (direct, indirect, and/or cumulative) on the resource to be studied, and how the study results would inform the development of license requirements;

6.    Explain how any proposed study methodology (including any preferred data collection and analysis techniques, or objectively quantified information, and a schedule including appropriate field season(s) and the duration) is consistent with generally accepted practice in the scientific community or, as appropriate, considers relevant tribal values and knowledge; and

7.    Describe considerations of level of effort and cost, as applicable, and why any proposed alternative studies would not be sufficient to meet the stated information needs.

While applications for a new license are not directly considered in this report, the study approaches discussed would be equally relevant.  Additional information on the FERC relicensing process can be found at the following link:



This report has two parts:

  • Part I - Matrix of potential hydropower effects on ecological, cultural, recreational, and aesthetic resources; and
  • Part II - Description of scientific approaches for evaluating the effects identified in the matrix. 


A matrix was developed to provide stakeholders involved in the relicensing process with a list of potential effects for consideration during initial evaluation of a project (Part I).  This matrix is organized based on typical hydropower facilities and operations, and identifies the pathways by which these facilities and operations potentially affect various resources.  Next, scientific approaches for evaluating these effects were described and compared (Part II), following the same categorical structure mapped in the matrix.  The scientific approaches are organized by resource area, which is consistent with most FERC reporting requirements.

Peer Reviewers

The development of this report relied on interaction with and contributions from HRC, government regulatory agencies, and industry representatives most involved in the relicensing process to ensure that final product is a useful tool.  This report represents the collaborative effort of leading scientists in their respective fields, including agency, academic, utility, and private-sector professionals.  However, any errors in this document are the sole responsibility of the primary authors.  The input from the following contributors to this project is acknowledged and appreciated: 

Fred Ayer (Executive Director, Low Impact Hydropower Institute), Hal Beecher, Ph.D. (Instream Flow Biologist, Washington Department of Fish and Wildlife), John Beuttler (Conservation Director, California Sportfishing Protection Alliance), Jim Canaday (Senior Environmental Scientist, FERC Relicensing Team, California State Water Resource Control Board), Tim Downey (Staff Ecologist, Eugene Water & Electric Board), Monte Garrett (Wildlife Biologist, Hydro Resources Department, PacifiCorp), Ann Gray (relicensing expert, U.S. Fish and Wildlife Service [USFWS]–personal review, not necessarily representing the positions of the USFWS), Dean Grover (Fisheries Biologist, USDA Forest Service), Jennifer Huff (Hydro Licensing, Duke Energy), Josh Israel (Board President, Salmon Restoration Federation), Gerrit Jöbis (Director of Southeast Conservation, American Rivers), Ken Kimball (Director of Research, Appalachian Mountain Club), Kurtis Knight (Northeast Area Manager, California Trout), Jan Konigsberg (Alaska Public Waters Coalition and Natural Heritage Institute), Paul Kubicek (Supervising Aquatic Biologist, Pacific Gas & Electric Company), Kevin Lewis (Conservation Director, Idaho Rivers United), Kaitlin Lovell (Salmon Policy Coordinator, Trout Unlimited), David Marcus (Economist), Kate Miller (Salmon Legal Analyst, Trout Unlimited), David Moller (Hydro Relicensing Director, Pacific Gas & Electric Company), Laura Norlander (Director, California Hydropower Reform Coalition), Tom O’Keefe (Ph.D, Pacific Northwest Stewardship Director, American Whitewater), Phil Raab (Hydropower Coordinator, USDA Forest Service), Helen Sarakinos (Dams Program Manager, River Alliance of Wisconsin), Frank Simms (Hydro Support Manager, American Electrical Power), Dave Steindorf (California Stewardship Director, American Whitewater), Mike Taylor (Hydrologist, USDA Forest Service), Eric Theiss (Hydro Coordinator, National Marine Fisheries Service), Craig Tucker (Klamath River Campaign Coordinator, Karuk Tribe), and Gene Vaughan (Senior Scientist, Duke Energy).