LIHI Certificate #100 - South Milton Hydroelectric Project, New Hampshire
The South Milton Hydroelectric Project is located on the Salmon Falls River in the town of Milton, New Hampshire. The Salmon Falls River originates at Great East Lake about twelve miles due north of the Project site. The river flows principally southeast from the Project site to join the Cochecho River, which flows in from the west in the town of Dover, New Hampshire. Together they form the Piscataqua River, which is a tidal river that enters the Atlantic Ocean twelve miles downstream in Portsmouth, New Hampshire and Kittery, Maine. The Salmon Falls River, with a length of 38 miles, forms a portion of the southern border between New Hampshire and Maine. Except for the Project dam, all Project infrastructure is located in New Hampshire.
The Project dam is one of fifteen dams located on the Salmon Falls River. Six federally licensed or exempted hydroelectric projects are located between the Project and South Berwick, Maine: North Rochester (FERC Project No. 3985), Boston Felt (FERC Project No. 4542), Somersworth (FERC Project No. 3820), Lower Great Falls (FERC Project No. 4451), Rollinsford (FERC Project No. 3777), and South Berwick (FERC Project No. 11163). Below South Berwick, the river becomes tidal for its last three miles before entering the Piscataqua River. The mills on the upper Salmon Falls River were initially developed in the early 1900’s by the Jonas Spaulding, a partner in Spaulding Fiber, a manufacturer of leatherboard, transformer board, and vulcanized fibre founded in 1873 in Townsend Harbor, Massachusetts. The New Hampshire mills were operated for leatherboard manufacture under the name the J. Spaulding and Sons. Dams related to this manufacturing enterprise persist. Project works consist of: (1) a 164-foot-long concrete-capped timber crib dam which is 16.4 feet high at its highest point; (2) a 6-foot 6-inch-diameter, 3,800-foot-long steel penstock; (3) a powerhouse located in the former Spaulding Fiber Company Mill 4,600 feet downstream of the dam; (4) three turbines, with Units 1, 2, and 4 located in Mill Building No. 1 and Unit 3 located in adjacent Mill Building No. 2. Mill building No. 1 is considered the primary powerhouse with the controls and electrical cubicles situated within. Each of the generating units has individual draft tubes which discharge flow into a common tailrace. The Project dam forms a 100-acre impoundment with an average depth of 15 feet and a gross storage capacity of about 768 acre-feet. The FERC exemption application indicates that the headpond elevation is 340 feet and the tailwater 238 feet, presumably referenced to sea level. The dam was completed in 1893. The upper six feet of the dam consists of stanchion stoplogs. Two 10.5 feet wide by 6.5 feet high wooden wastegates were incorporated in the structure in 1999. The gates are motorized. The intake structure is comprised of a trashrack, a custom built trash rake system, a manually operated headgate, and a transition section which feeds thee penstock. The trashrack rake system is operated manually on a daily basis and more frequently during specific times of the year such as during the fall and during ice break-up periods.
The station has a capacity of 1.55 MW.
|Project Name||South Milton|
|LIHI Certificate No.||100|
|LIHI Certificate Term||September 6, 2017 - September 5, 2022|
|Owner||Salmon Falls River Hydro Corporation|
|Location||Located at river mile 26 on the Salmon Falls River in the town of Milton, New Hampshire.|
|Installed Capacity||1.55 MW|
|Average Annual Generation||6,200 MWh|
|FERC No.||P-3984 exempt 1981|
Certification HistoryMarch 13, 2018: On March 11, 2018, the 30-day appeal window for the preliminary decision to recertify the South Milton Hydroelectric Project ended with no appeals filed. The recertification decision is therefore final. The term of Low Impact Certification for the South Milton Hydroelectric Project is from September 6, 2017 until September 5, 2022. February 9, 2018: The South Milton Hydroelectric Project has received preliminary approval for a new 5-year term of Low Impact Certification. The Certification includes the following conditions:
- Condition 1: The Owner shall continue to maintain a minimum flow of 58 cfs, or inflow if less, in the bypassed reach of river.
- Condition satisfied 2018. Condition 2: The Owner shall revise the Project flow monitoring plan to clarify and specify the method for releasing into the bypassed reach the required minimum flow (58 cfs, or instantaneous inflow if less), and true run-of-river operation, and how records will be maintained to demonstrate compliance with the bypass reach minimum flow and true run-of-river operation. The Owner shall submit the final plan revision to U.S. Fish and Wildlife Service, the N.H. Department of Fish and Game, and the N.H. Department of Environmental Services and obtain agency concurrence on the revised plan. The Owner shall submit the final plan as an update to FERC within 90 days of agency concurrence and copy LIHI on the filing in the following annual compliance report filed with LIHI.
- Condition 3: The Owner shall continue to operate and maintain safe, timely, and effective upstream passage facilities for American eel in coordination with the N.H. Department of Fish and Game, the Maine Department of Marine Resources, and the U.S. Fish and Wildlife Service. The Owner shall monitor effectiveness using means acceptable to the agencies and report results annually to the agencies and in the annual compliance reports filed with LIHI. If, during the LIHI Certification term, agencies determine that eel passage is not effective, the Owner shall consult with agencies to develop and implement modifications to the passage facility. The status of consultation and any modifications to eel passage will also be reported to LIHI in the annual compliance reports.
- (1) SFR Hydro shall maintain a minimum flow of 58 cfs, or inflow if less, in the penstock-bypassed reach of river. This condition is deemed satisfied by LIHI on consultation with Certificate Holder- 9/2/15
- (2) After consultation with the USFWS, the N.H. Department of Fish and Game, and the N.H. Department of Environmental Services, SFR Hydro shall revise the Project flow monitoring plan to address the method for releasing the bypass minimum flow and how records will be supplemented to enable demonstration of compliance with the bypass minimum flow. The revised plan will be filed with FERC for approval within 90 days of LIHI’s grant of certification; SFR Hydro shall copy LIHI on the filing. This condition is deemed satisfied by LIHI on consultation with Certificate Holder- 9/2/15. See Flow Monitoring Plan posted in Files below.
- (3) By October 1, 2013, SFR Hydro shall enter into, and provide LIHI with a copy of, an agreement reached between the USFWS, the New Hampshire Department of Fish and Game, and SFR Hydro for providing both interim and permanent downstream passage and permanent upstream passage, that are safe, timely, and effective, for American eel, including a description of the planned passage and protection measures and the implementation schedule for design, installation, and operations. Said permanent facilities for upstream and downstream passage shall be in place and operational by August 1, 2015, and SFR Hydro shall notify LIHI within two weeks of completion. Pending the agreement, SFR Hydro shall continue providing downstream passage by maintaining the exclusionary trashracks and passing eels through the opening in one sluicegate during the period August 15 to November 15. In the event that the USFWS and the New Hampshire Department of Fish and Game determine prior to the installation of permanent downstream passage that the above-described interim downstream passage measure is not providing safe, timely and effective interim passage for outmigrating eels, SFR Hydro shall implement other reasonable interim measures as requested by these agencies. In August 2015 SFR completed Eel Passage construction, see Eel Passage Design in files below. Agency approval is pending.
- (4) In the event that the facility owner decides to undertake any new activities that may have an adverse effect on historic properties, such as new excavation, demolition, and structural alteration, the facility owner shall notify LIHI within 30 days of such decision. The facility owner shall then consult with, and obtain approval from, the State Historic Preservation Office of such activities and send LIHI a copy of that approval when it is obtained.