Ashton Hydroelectric Project, Henry’s Fork River, Idaho
Portland, Maine - (October 22, 2010) At their Annual Meeting, the Low Impact Hydropower Institute’s Governing Board determined that the Ashton Hydroelectric Project meets the LIHI Certification Criteria. In reaching its decision to certify the Ashton Hydroelectric Project, the Low Impact Hydropower Institute’s Governing Board reviewed the application for certification, as well as the Application Reviewer’s report. The Board’s vote to certify the Ashton Hydroelectric Project was unanimous. LIHI received the following public comments on PacifiCorp's application for certification for the Ashton Project:
The Henry's Fork Foundation, Inc filed comments in February 2010 and a copy of this letter is contained in Appendix A of the Application Reviewer’s report. The Foundation focuses on protection of the fisheries, wildlife and aesthetic qualities of the Henry's Fork watershed. The letter acknowledges that the "Ashton Dam facility may meet the eight certification criteria", however the Foundation recommends that the certification review of the project be delayed until after completion of the Dam Remediation Project scheduled for 2010 - 2012. The major reason given for the delay recommendation is the concern of sediment release during the multiple planned significant reservoir drawdowns, and the impacts that could result. Comments were also provided in the areas of River Flows, Water Quality, Fish Passage and Protection and Recreation. As noted in Section 4.0, Record of Communications, of the Application Reviewer’s report a discussion was held with Mr. Stephen Trafton, Executive Director of the Foundation, to obtain clarification of some of the comments. Most of his concerns involve river flows; clarifying information on the Foundation's comments is presented under the Section 2.1 Criteria A - River Flows discussion of the Application Reviewer’s report.
The Board approves certification for the Ashton Hydroelectric Project for five-years with project specific conditions.
1. Because there are questions regarding flows and water quality associated with the Dam Remediation Project, the Board imposed non-standard conditions similar to those included in the Consent Order established for the remediation work. The Applicant will provide LHI with notifications of events that include:
A. a letter notification within two weeks, of drawdown and other potential sedimentation causing activities which are required to be provided to the IDEQ within 24 hours; and,
B. a letter documenting any sedimentation events that required implementation of the Best Management Practices (BMPs) under the Consent Order.
This documentation shall describe the event, BMPs implemented to mitigate the problem, and impacts that have occurred. LIHI would have the authority to request additional information from PacifiCorp, and consultation with applicable resource agencies, to allow LIHI to determine continuing compliance with the Low Impact certification criteria.
2. The Project's Water Quality Certificate is dated 1985, and there is no quantitative data to document compliance with quantitative water quality standards. However, the fisheries are very healthy below the dam, which in part, suggests that water quality in the waters downstream of the Project is good. As a result, LIHI requires the following second set of conditions:
A. PacifiCorp shall provide LIHI, a copy of the same documents submitted to the IDEQ, and on the same schedule, as required under the Water Quality Monitoring Plan of the Consent Order established with the IDEQ;
B. PacifiCorp shall provide LIHI a letter from the IDEQ, attesting to PacifiCorp's compliance with requirements of the Consent Order, within 3 months of each filing made to the IDEQ;
C. Within two years of certification, documentation is submitted to LIHI showing agreement has been reached with the IDEQ on a water quality testing regime, to be implemented at the conclusion of the Remediation project, demonstrating that quantitative water quality standards are being met for parameters potentially impacted by Project activities in the reservoir and downstream: and,
D. Not later than 18 months following completion of the Remediation Project, PacifiCorp shall submit to LIHI, the data showing that these quantitative water quality standards are indeed being met, with confirming letter from IDEQ.
The effective certification date for the Ashton Hydroelectric Project is December 31, 2009 and will expire on December 31, 2014.
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Ashton Powerhouse and Dam
Portland, Maine (December 31, 2009) – The Low Impact Hydropower Institute (LIHI) announced today that PacifiCorp Energy ("PacifiCorp" or "Applicant") has submitted an application for certification of the Ashton Hydroelectric Project on the Henry's Fork of the Snake River ("Henry's Fork") in Idaho. PacifiCorp owns two hydroelectric developments on the Henry's Fork: Ashton and St. Anthony. Both projects are licensed by FERC as Project No. 2381. This application for Low Impact Hydropower Certification pertains to the Ashton development. The St. Anthony development is not currently operational due to an outage of the generating unit in 2003. PacifiCorp is exploring decommission or sale of the St. Anthony's development in consultation with FERC.
The Henry's Fork watershed in eastern Idaho and western Wyoming encompasses 1.7 million acres and over 3,000 miles of rivers, streams and canals. The river originates from the outlet of Henry's Lake, located in the Continental Divide Mountains. The Upper Henry's Fork subbasin, located in eastern Idaho, encompasses 1,068 square miles, including 30 square miles in Wyoming and 60 square miles in Yellowstone National Park. The northern extent of the subbasin is bounded by the continental divide, which also delineates the boundary between Idaho and Montana. The subbasin is located within the Greater Yellowstone Ecosystem and possesses many of the unique geological, scenic, recreational, and wildlife attributes for which Yellowstone National Park is valued. The majority of the subbasin is managed by the U.S. Forest Service.
Bald Eagles on Artificial Perch
The Ashton dam, located at river mile 45 of the Henry's Fork of the Snake River (Henry's Fork), forms the southern boundary of the Upper Henry's Fork subbasin. After exiting the subbasin, the Henry's Fork continues in a southwesterly direction for 79 miles through the Lower Henry's Fork subbasin before reaching its confluence with the South Fork of the Snake River. The Ashton dam and powerhouse are situated in a sparsely populated, semi-arid area in which the dominant land uses are irrigated agriculture and outdoor recreation, particularly trout angling and hunting. The Idaho Department of Fish and Game lists the Henry's Fork as Value Class I, the highest class possible for fishery resources. The area's topography is flat to gently rolling, and its climate is characterized by warm, dry summers and cold, snowy winters.
The Ashton development is comprised of a 56.6-foot-high, 226-foot-long, earth and rock-filled dam that has a downstream slope covered with roller compacted concrete and an upstream slope stabilized by additional rock fill. The crest elevation of the dam is 5156.6 msl. There are two- foot-high flashboards on the dam crest to prevent spillage from reservoir wave action and an 82- foot-long reinforced concrete spillway surmounted by six 10-foot-high radial gates. The reservoir has a surface area of 404 acres, with a gross storage capacity of 9,800 acre-feet and a usable storage capacity of 3,988 acre-feet at normal water surface elevation (5156.6 feet msl). The development features a reinforced-concrete powerhouse located at the right bank, with integral intakes controlled by vertical slide gates and containing two generating units, each with a nameplate rating at 2,000 kW, and one generating unit rated at 2,850 kW.
Ashton Spillway looking upstream
In consultation with FERC, PacifiCorp plans to rehabilitate Ashton Dam in 2010-2011 to mitigate seepage and piping (i.e., internal erosion) risks posed by a deteriorating upstream silt core within the dam. The rehabilitation will involve excavating and reconstructing a portion of the upstream embankment. Other features of the project include replacing the headrace retaining wall, replacing the concrete crest structure, and adding a concrete overlay to an unprotected portion of rockfill between the spillway and the powerhouse.
PacifiCorp operates the Ashton development in an instantaneous run-of-river mode for the protection of fish and wildlife resources in the Henry's Fork. The average annual generation of the facility is 36,916 Mwh. The facility has a 46/2.3-kV step-up transformer and electricity is conveyed to the substation via a 133-foot-long, 46-kV transmission line. Run-of river operations will be maintained during the planned rehabilitation of Ashton Dam except during drawdown and refill periods. A low-level outlet tunnel will be installed to provide river diversion during construction. The outlet tunnel will be constructed through the right abutment bedrock and will include a vertical shaft housing slide gates for flow control.
Ashton Reservoir South Shore
Public Comments- We encourage public comments on this application. Specifically, we are interested in knowing whether you think the Ashton Hydroelectric Project meets our LIHI criteria. Review the program and criteria in greater detail and then review the Ashton Hydroelectric Project's application. 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 info@lowimpacthydro.org with " Ashton Hydroelectric 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 March 3, 2010 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.
Notice - March 1, 2010 - LIHI received a comment letter from the Henry's Fork Foundation. A copy of the letter can be read or downloaded by clicking this link Ashton LIHI on ltrhd.doc at the bottom of this page.
Ashton Reservoir North Shore
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