LIHI Certifies Arrowrock Dam (FERC No. 2334 ) as Low Impact Hydro
Portland Maine - (October 31, 2011) - At their October 27, 2011 meeting the Institute’s Governing Board determined that the Arrowrock Hydroelectric Project met the LIHI Certification Criteria. In reaching its decision to certify the Arrowrock Hydroelectric Project, the LIHI’s Governing Board reviewed the application for certification, as well as the Application Reviewer’s report. The Board’s vote to certify the Arrowrock Hydroelectric Project was unanimous, and the Board approves certification for the Arrowrock Hydroelectric Project for five-years. The effective certification date for the Arrowrock Hydroelectric Project is April 30, 2011 and will expire on April 30, 2016. Any Commenter may submit a letter to the Certification Administrator requesting an appeal within 30 days of the posting of the Certification Decision on the Institute’s Web page. An appeal request must include specific reasons why the hydropower facility should have failed one or more criteria. If an individual or organization did not comment on the initial Application Package, they may not file an appeal.
Portland, Maine (April 30, 2011) – The Low Impact Hydropower Institute (LIHI) announced today that the Clatskanie Peoples Utility District, Clatskanie, Oregon (“Applicant” or “PUD”)[1] has submitted an application for Low Impact certification of the Arrowrock Hydroelectric Project.
Project Description - The Arrowrock Hydroelectric Facility is a run of river facility with daily shaping allowed in FERC license. The primary project components include: 1) two 58-inch diameter steel penstocks, 2) a 70-foot-high powerhouse, 3) two 7.5-MW Francis turbine generating units, 4) a 55-foot-wide, 125-foot-long tailrace discharging into Lucky Peak Lake, 5) and electrical transmission infrastructure including generator leads, switchyard, and transmission interconnection with the Idaho Power Company system.
A series of ten outlet conduits extend through Arrowrock Dam. Clamshell gates installed on the downstream end of each conduit are used to control water releases through the dam. There is also an overflow spillway on the dam which is used occasionally to release water for flood control. The Project will receive water via two 58-inch diameter steel penstocks that divert flows from the downstream end of two of the ten existing outlet conduits to the hydroelectric facility. The remaining eight outlet conduits will continue to discharge directly into Lucky Peak Lake. Therefore, only a small portion of the water discharged through the dam will be diverted through the turbines.
The powerhouse and tailrace are located on a basalt bench (elevation 3040) immediately downstream of Arrowrock Dam. The tailrace will be lined with concrete to minimize water leakage and percolation through the basalt. Water volumes will range from 350 to 810 cubic feet per second per turbine. Butterfly shutoff valves with flow-through design are being installed on the turbine inlets. A control weir (approximate elevation 3022) has been constructed at the downstream end of the tailrace to ensure draft tube submergence.
Releases from the Arrowrock Dam are made by the Bureau of Reclamation for flood control and irrigation purposes. The project is allowed to shape the flows that the Bureau of Reclamation determines to release on a daily basis only. Thus if the Bureau of Reclamation determines to release a certain amount of water on a particular day, the FERC License allows the Owner to shape as much of that pre-determined daily release during peak hours as possible. The purpose of this limitation on shaping was to prevent injury to bass spawning and recreation uses in the downstream reservoir – Lucky Peak Lake. The Arrowrock Hydroelectric Facility is not a load following or peaking facility. It can only use what the Bureau of Reclamation determines to release. Because the project flows exceed the capacity of the Facility between April and August of each year, no daily shaping is expected to take place. From November to March daily flow shaping is expected to occur only about 10% of the time.
In addition the Facility cannot operate at heads below 70 feet net head and thus cannot operate when the risk of entrainment of fish is the greatest. The USFWS issued a Biological Opinion for this project because of the presence of a listed threatened species - bull trout - in the Arrowrock reservoir. The Bureau of Reclamation previously consulted with the USFWS on the dam and reservoir operations and received their own Biological Opinion. The USFWS Biological Opinion for the hydroelectric Facility concluded “the potential for the Project to result in entrainment beyond that anticipated under Reclamation’s existing operations will not result in effects to bull trout in Arrowrock Reservoir that could be meaningfully measured, detected, or evaluated.” USFWS (2008) p. 26.
PUBLIC COMMENT
We encourage public comments on each of these applications. Specifically, we are interested in knowing whether you think these Projects meet our LIHI criteria. Review the program and criteria in greater detail and then review the Project or Projects that you have an interest in. Your 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 (preferred) at info@lowimpacthydro.org with " Arrowrock Project Comments," in the subject line; by fax at (206) – 984-3086; or by mail addressed to LIHI, 34 Providence Street, Portland, ME, 04103. Comments must be received at the Institute on or before 5 pm Eastern time on June 30, 2011 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.
[1] The Applicant is not the Facility owner/operator. The facility is an add-on to an existing United States Bureau of Reclamation dam and is owned by Boise Kuna Irrigation District, Nampa & Meridian Irrigation District, New York Irrigation District, Wilder Irrigation District and Big Bend Irrigation District, Boise, Idaho.