The Lawrence Project is located on the Merrimack River in the city of Lawrence, Essex County, Massachusetts. The Project works consist of: (1) a 33-foot high, 900-foot-long dam of rubble masonry construction with five-foot-high inflatable flashboard system; (2) a 9.8-mile-long reservoir having a surface area of 655 acres at normal high water elevation 44.17 feet mean sea level (msl) and a maximum storage capacity of approximately 19,900 acre-feet; (3) the existing South Canal approximately 35 feet wide and 10 feet deep, originating at the south abutment of the Essex Dam and generally paralleling the Merrimack River bed, below the Essex Dam, for a distance of approximately 2,750 feet; (4) the existing North Canal, approximately 95 feet wide and 15 feet deep, originating at the north abutment of the dam and paralleling the Merrimack River below the dam for a distance of approximately 5,300 feet; (5) fish passage facilities including a fish elevator installed at the dam, a downstream fish bypass and an eel ladder; (6) a powerhouse containing two 8.4 MW hydroelectric generating units and a tailrace channel extending into the Merrimack River Channel; and (7) appurtenant facilities.

Project Name Lawrence
LIHI Certificate Number 121
LIHI Effective and Expiration Dates March 13, 2015
March 13, 2020
Owner Essex Company, LLC
State Massachusetts
Location Located at river mile 31 on the Merrimack River in the city of Lawrence, Essex County, MA.
Installed Capacity 16.8 MW
Average Annual Generation 64,600 MWh
Facility Type Run-of-river
FERC No. 2800

The Lawrence Project is operated in a run-of-river mode through use of an automatic pond level control (PLC). The upstream fish passage operation typically begins annually in late April and continues through mid-July and from mid-September through October, with final operation schedule determined in consultation with resource agencies. Upstream fish passage lifts generally occur between 8:00am to 4:00pm daily during the operational periods and maintains operations up to river flows of 25,000 cfs with a 120 cfs attraction flow provided for the fish elevator system. The downstream fish passage bypass operation typically begins annually on April 1 and continues through mid-July and from September 1 through November 15, with final operation schedule determined in consultation with resource agencies.

The Lawrence Project’s dam is equipped with a pneumatic inflatable flashboard system. The system varies air pressure to adjust the flashboard height to maintain normal headpond elevation at the Project based on the river user needs, flow and weather conditions. The installation of the system eliminated the need for impoundment drawdowns required for flashboard replacement, enhanced river debris management with reduced debris build up near the dam, enhanced high flow condition management and reduced false fish attraction away from the fish passage facilities often caused by board leakage and partial board loss.

The South Canal is closed annually during the spring and fall outmigration seasons. The South Canal is closed each year after the 3-day average Merrimack River flow drops to 12,000 cfs or lower. The South Canal is reopened on July 15 and closed. In the fall, the South Canal is closed from September 1 to November 15.



LawrenceDam Flashboards





Certification History

July 1, 2015 – Executive Director Michael J. Sale, using authority delegated from the LIHI Governing Board and a full review of the Application Reviewer’s report and all public comments and additional materials provided by the Applicant, has determined that the Lawrence Hydroelectric Project (FERC No. P-2800) satisfies the LIHI Certification Criteria. The effective certification date for the Lawrence Project is March 13, 2015 for a five (5) year term, which will expire on March 13, 2020, with the following project specific conditions:

  • Condition satisfied in 2016. Applicant will obtain a final letter from Massachusetts Department of Fish and Wildlife (or other agency recommended by MDFW) that confirms the facility and facility operations have no negative impact on the existence of Bald Eagle in the area, by August 1, 2015.
  • Condition satisfied in 2016. Applicant will work with MDFW to improve effectiveness of eel passage at the site by July 15, 2016. This includes keeping elvers off dam by eliminating or rerouting leakage. Applicant will obtain letter from MDFW by July 15, 2016 that confirms passage measures are adequate.

March 16, 2015 – On March 13, 2015, the Low Impact Hydropower Institute (LIHI) received a complete application from Lawrence Hydroelectric Associates, a subsidiary of ENEL North America Inc., for the Low Impact Certification of the Lawrence Project, FERC P-2800, located on the Merrimack River in the city of Lawrence, Essex County, Massachusetts.