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Arrowrock Dam Outlet Works Rehabilitation, INT-DES 00-45

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Bureau of Reclamation, Interior.


Notice of availability of Draft Environmental Impact Statement and notice of public hearings.


Pursuant to section 102(2)(C) of the National Environmental Policy Act of 1969, as amended, the Department of the Interior, Bureau of Reclamation (Reclamation) has prepared a draft environmental impact statement (Draft EIS) to examine the impacts of alternatives to rehabilitate the outlet works at Arrowrock Dam. The Bureau of Reclamation proposes to remove 10 lower level Ensign valves and replace them with clamshell gates. Two action alternatives have been identified that differ only in the timing of reservoir drawdown and the elevation of Arrowrock Reservoir and Lucky Peak Lake in the third construction season. The preferred alternative requires a longer period of drawdown of Arrowrock Reservoir, but both Arrowrock Reservoir and Lucky Peak Lake would remain at a higher elevation than with the other action alternative. The No Action Alternative is also evaluated. The No Action Alternative is defined as the most likely future without the proposed project, and includes actions that would be required for an intensive maintenance program if the Ensign valves were not replaced.


Written comments on the Draft EIS must be submitted by January 5, 2001, to the address listed under the Addresses Section. Public hearings to accept oral comments on the Draft EIS will be held on December 12, from 1 to 4 p.m. and from 5 to 8 p.m. in Boise, Idaho. Persons requiring any special services at the public hearing should contact Mr. Tiedeman (see below) by December 5, 2000.


The public hearings will be held at the Idaho State Historical Museum, Second Floor Conference Room, Julia Davis Park, 610 N. Julia Davis Drive, Boise, ID.

Written comments on the Draft EIS should be submitted to: Mr. John Tiedeman, Bureau of Reclamation, 1150 N. Curtis Road, Suite 100, Boise ID 83706-1234.

Our practice is to make comments, including names and home addresses of respondents, available for public review. Individual respondents may request that we withhold their home address from public disclosure, which we will honor to the extent allowable by law. There also may be circumstances in which we would withhold a respondent's identity from public disclosure, as allowable by law. If you wish us to withhold your name and/or address, you must state this prominently at the beginning of your comment. We will make all submissions from organizations or businesses, and from individuals identifying themselves as representatives or officials of organizations or businesses, available for public disclosure in their entirety.

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Mr. John Tiedeman, (208) 378-5034.

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Arrowrock Dam and Reservoir, completed in 1915, were constructed by the Bureau of Reclamation (Reclamation) as part of the Boise Project. The dam is located on the main stem Boise River about 17 river miles upstream from the city of Boise and is operated as one of three storage facilities constructed on the Boise River. Anderson Ranch Dam and Reservoir, located on the South Fork Boise River and generally east of Arrowrock Dam, were completed by Reclamation in 1950 as part of the Boise Project. Lucky Peak Dam and Lake, located to the southwest and about 11 river miles downstream of Arrowrock Dam, were completed by the U.S. Army Corps of Engineers (Corps) in 1957. Reclamation and the Corps operate the three storage dams in a coordinated method for irrigation water supply (Reclamation markets the water supply in Lucky Peak Lake for irrigation), flood control, recreation, and fish and wildlife.

Reclamation began considering modification of Arrowrock Dam outlet works in 1982; some conceptual designs for replacement of some of the Ensign valves were developed in 1983. Over several years, various possible designs were identified and evaluated, and in 1987 a conceptual design suggested clamshell gates. Increasing maintenance problems resulted in the current effort to identify and evaluate solutions to the maintenance problems associated with the now 85-year old Ensign valves. The scope of this study was limited to valve replacement to retain and improve operational flexibility of Arrowrock Dam and Reservoir. Reclamation's scoping process has included numerous meetings with state and Federal agencies, local groups, and interested individuals. Notices of intent to prepare an EIS and to hold public scoping meetings were published and two public scoping meetings were held on November 20, 1998. The results of meetings and comments have been considered in the development of alternatives.

The Draft EIS is limited to the potential effects of replacing the lower row of Ensign valves with clamshell gates. Reclamation has deferred maintenance and replacement activities on the lower Ensign valves since 1988 so that action alternatives could be identified and compared to a No Action alternative consisting of an aggressive maintenance program. Environmental effects of the action and No Action alternatives were analyzed for the stream reaches and reservoirs upstream and downstream from Arrowrock Dam and Reservoir. Potential environmental effects are generally limited to those associated with construction and the reservoir drawdowns necessary for maintenance and replacement of the lower outlets. A major concern associated with the drawdowns is bull trout which are found in Arrowrock Reservoir and the streams upstream; bull trout were listed as a threatened species in June 1998.

Those wishing to obtain a copy of the Draft EIS or schedule time, in advance, to make oral comments at the hearing(s) may contact Mr. Tiedeman. Speakers will be called in order of their requests. Requests to comment may also be made at each hearing and speakers will be scheduled to follow the advance requests. Comments will be limited to 10 minutes and will be recorded by a court stenographer to be included in the hearing record. The Draft EIS is available for viewing on the internet at​project/​arrowrock/​arrowrock.shtml.

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Dated: October 16, 2000.

J. William McDonald,

Regional Director, Pacific Northwest Region.

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[FR Doc. 00-27595 Filed 10-25-00; 8:45 am]