LIHI Certificate #114 - Mahoning Creek Project, Pennsylvania

On March 4th 2011, the Federal Energy Regulatory Commission (FERC) issued an order granting an original license to construct, operate and maintain the proposed 6.0 MW Mahoning Creek Hydro Electric Project (Project) No. 12555 to the Mahoning Creek Hydroelectric Company, LLC. The Project is built at the existing Mahoning dam and includes a 50-foot-high intake structure attached to the upstream face of the dam, a 1,090-foot-long, 10-foot-diameter penstock, and a powerhouse containing a 4-MW and a 2-MW vertical-shaft generating unit. Construction of the project began in March 2013 and the facility began commercial operations in December 2013.

The existing Mahoning dam and reservoir were constructed by the US Army Corps of Engineers (“USACE”) beginning in 1939 and became operational in 1941. The dam was designed with two conduits built into the south abutment of the dam for future hydropower development. The USACE project consists of: a 162-foot-high, 926-foot-long dam with 192-foot-long spillway section equipped with five 29-foot-high, 30-foot-long vertical lift gates (i.e., sluice gates), impounding a 5-mile-long, 280-acre reservoir with a normal pool elevation of 1,077 feet mean sea level (msl); and a 192-foot-wide, 950-foot-long stilling basin regulated by a 180-foot-long flat-crested stilling basin weir and located downstream of the dam. The Mahoning dam is located on Mahoning Creek in Armstrong County, Pennsylvania. The dam is located 21.6 miles upstream from the junction of the creek and the Allegheny River.  It is one of 16 flood control projects in the USACE Pittsburgh District used to provide flood protection to the lower Allegheny River Valley and the upper Ohio River.

USACE operates the dam in a modified run-of-river mode to augment flow during dry periods to maintain downstream water quality and as water supply for domestic, industrial, and recreational uses. The USACE maintains the summer pool elevation at 1,100 feet msl ± 0.5 foot, and during the fall, the pool level is lowered to elevation 1,075 feet msl to provide flood storage capacity. An Adaptive Management Plan (AMP) with USACE dictates the minimum flows released through the USACE bypass. Depending on the time of year the minimum discharge  ranges from 30 cfs – 60 cfs to ensure that existing water quality conditions are maintained.

Currently, the dam’s primary use is for flood control and storm water management; however, the dam and the area surrounding it are often used for recreational activities, such as boating, fishing, hiking, hunting, trapping, and picnicking. The hydroelectric Project generates clean, carbon-free electricity in accordance with the current dam operation established by USACE.  Therefore, the Project has no negative impact on the current uses of the dam, the planned uses of the dam, or the surrounding and downstream environment. The Mahoning Creek team worked closely with USACE, FERC, Pennsylvania Department of Environmental Protection, and state and local authorities to ensure that the Mahoning Creek Project maintained existing water quality conditions throughout construction and during operation of the Project.

Project Name Mahoning Creek
LIHI Certificate No. 114
LIHI Certificate Term November 14, 2018 - November 13, 2028
Owner Mahoning Creek Hydroelectric Company
State Pennsylvania
Location Located on Mahoning Creek in Armstrong County, Pennsylvania. The dam is 21.6 miles upstream from the junction of the creek and the Allegheny River.
Installed Capacity 6.0 MW
Average Annual Generation 18,500 MWh
Facility Type Modified run-of-river
FERC No. P-12555 issued 2011, expires 2061

Certification History

November 7, 2019: The decision to recertify the Mahoning Creek project is final. No appeal requests were received during the appeals period that closed November 2, 2019. The project is recertified with a term from November 14, 2018 – November 13, 2028. The Certification includes two conditions:

  • Condition 1: The facility Owner shall continue to cooperate and participate in any new studies of ecological flow requirements at the Project and provide copies of any study reports and related consultation to LIHI in annual compliance statements.
  • Condition 2: The facility Owner shall continue to work with USACE to investigate possible flexibility in the existing Water Control Manual to keep short-term dam releases at higher, more stable minimum levels. If such flexibility can be agreed to between USACE and the Owner, the Owner shall implement improved minimum releases.

October 3, 2019: The Low Impact Hydropower Institute has preliminarily approved Low Impact Recertification for the Mahoning Creek Hydroelectric Project, LIHI #114.

This decision is preliminary pending the 30-day appeal window. Only those who commented on the initial application during the 60-day comment period are eligible to file an appeal. Such appeal needs to include an explanation as to how the Project does not meet the LIHI criteria. Appeal requests can be submitted by email to with “Mahoning Creek Hydroelectric Project” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, 329 Massachusetts Ave, Suite 6, Lexington, MA 02420. All requests will be posted to the website.  The applicant will have an opportunity to respond and any response will also be posted. Requests must be received by 5 pm Eastern time on November 2, 2019.  The full application and reviewers report are available below.

If no appeal requests are received and the decision becomes final, the Certification term for the Project will be November 14, 2018 for a term of ten (10) years, which will expire on November 13, 2028.

July 31, 2019: The Low Impact Hydropower Institute has received a complete application for Low Impact Recertification of the Mahoning Creek Hydroelectric Project.  LIHI is seeking public comment on this application.  Specifically, we are interested in knowing whether you think the Project meets the LIHI Low Impact Certification Criteria, as revised in the 2nd Edition Handbook.  Please review the program and criteria in LIHI’s revised Handbook and then review the Project’s application materials below.

Comments that are directly tied to specific LIHI criteria (flows, water quality, fish passage, etc.) will be most helpful, but all comments will be considered.  Comments may be submitted to the Institute by e-mail at with “Mahoning Creek se Project Comments” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, 329 Massachusetts Avenue, Suite 6, Lexington, MA 02420.  Comments must be received on or before 5 pm Eastern time on September 29, 2019 to be considered.  All comments will be posted to the web site and the applicant will have an opportunity to respond.  Any response will also be posted.

June 18, 2014: The Mahoning Creek Project is certified as low impact for a five-year term, effective November 14, 2013 and expiring November 14, 2018.

January 13, 2014: Public comment period has closed.

November 14, 2013: Mahoning Creek Hydroelectric Company submitted an application for certification of the Mahoning Creek project; application posted to website and public comment period opened.


2019 Recertification

2014 Certification