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Intent To Prepare an Environmental Impact Statement for the Boise River General Investigation Feasibility Study, Ada and Canyon Counties, in the State of Idaho

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Department of the Army, U.S. Army Corps of Engineers, DOD.


Notice of intent.


The U.S. Army Corps of Engineers (Corps) intends to prepare an Environmental Impact Statement (EIS) for the Boise River General Investigation Feasibility Study. The Feasibility Study will evaluate alternatives to reduce flood risk and meet current and future water supply needs in the lower Boise River watershed. To the extent feasible, the study will also seek to provide ancillary ecosystem restoration benefits, minimize impacts to species listed under the Endangered Species Act (ESA) (16 U.S.C. 1531 et seq.), including bull trout, and minimize socioeconomic effects. The Feasibility Study will focus on the lower Boise River, a tributary to the Snake River, which is located in southwestern Idaho, primarily in Ada and Canyon Counties. The non-federal sponsor for this effort is the Idaho Water Resources Board.

Almost 40 percent of Idaho residents live in the Boise River watershed, with one-sixth of the State's population residing in the floodplain. Communities and development along the Boise River have experienced repeated minor flooding, and flood risk management experts emphasize that a significant flood event with major flood damage will likely occur in the future. The Boise River watershed has recently experienced the most significant growth in the State and continuing to meet current and future water needs is a major concern for residents and state/local officials.


Submit comments on the alternatives or scope of analysis for the EIS to Mr. Tim Fleeger, Project Manager, U.S. Army Corps of Engineers, Walla Walla District, CENWW-PM-PD-PF, 201 North Third Avenue, Walla Walla, WA 99362.

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Requests for further information should be directed to Mr. Tim Fleeger by phone at (509) 527-7247 or by email at

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This study was authorized by Section 414 of the Water Resources Development Act of 1999 (Pub. L. 106-53) as amended by Section 4038 of the Water Resources Development Act of 2007 (Pub. L. 100-114). Collectively, these two acts grant the Corps authority to conduct a study to determine the feasibility of undertaking flood risk management, water supply and ecosystem restoration on the Boise River. The Idaho Water Resources Board is authorized to study solutions for water supply and flood risk management, but is not authorized to expend funds studying ecosystem restoration. Therefore, the proposed Feasibility Study is focused on reducing flood risk and meeting current and future water supply needs along the Boise River, while seeking incidental environmental benefits to the extent feasible.

The Boise River is approximately 102 miles in length, is located entirely within the State of Idaho, and is one of the major tributaries to the Snake River. The lower Boise River watershed (the focus of the Feasibility Study) contains the Boise River drainage from Lucky Peak Dam to its confluence with the Snake River in southwest Idaho (roughly 64 miles). The lower Boise River floodplain encompasses primarily Ada and Canyon Counties, and includes the cities of Boise (state capital), Garden City, Meridian, Eagle, Star, Nampa, Middleton, Caldwell, Notus, and Parma. The Boise metropolitan area is the third largest in the Pacific Northwest after Seattle, Washington and Portland, Oregon.

The Boise River is highly regulated. Natural flows are modified by the three Federal storage projects on the upper river which are jointly operated by the Corps (Lucky Peak Dam) and the Bureau of Reclamation (Arrowrock and Anderson Ranch Dams) as a system for the primary purposes of flood risk reduction and irrigation water supply. Additional project facilities include Lake Lowell, an offstream storage reservoir operated by the Bureau of Reclamation, and numerous diversion canals that are federally or privately operated. Operation of the Federal reservoirs is a balancing act between reducing flood risk and having sufficient irrigation water for crops by mid-late summer. Recreation, hydropower, and general fish and wildlife functions are secondary authorized purposes. Water is not released for these purposes unless reservoir storage space is assigned for that specific purpose. A non-continuous series of non-Federal levees line the Boise River through developed areas in downtown Boise, Garden City and Eagle. A few are inspected through the Corps' Levee Safety Program, but the majority are unregulated and not maintained.

Complex, interconnected surface water and aquifer systems supply current water uses in the valley which includes irrigation and domestic, commercial, municipal, and industrial (DCMI) uses. Natural flow, stored surface water, and ground water are reused in multiple locations across the valley through a network of drains and direct discharge into the river. Surface water supplies an estimated 90 percent of the current DCMI water demand. Approximately 77 percent of the annual Boise River flow occurs as snowpack runoff during the March to July period.

The Corps will evaluate alternatives for their ability to reduce flood risk and provide water supply to the region. The preliminary range of alternatives will include, but is not limited to the following:

  • No Action;
  • Modification of Arrowrock Dam to provide additional flood risk management and water supply;
  • Modification of Arrowrock Dam along with downstream structural modifications, non-structural measures, and modifications to existing undeveloped lands to reduce effects from localized flooding;
  • Manage aquifer recharge to address future water supply along with downstream structural modifications, non-structural measures, and Start Printed Page 22809modifications to existing undeveloped lands to reduce effects from localized flooding.

The Corps invites affected Federal, State, local agencies, Native American tribes and other interested organizations and individuals to participate in the development of the EIS. Public information meetings will be conducted on May 6, 2014 from 6:00 p.m.-8:00 p.m. in Garden City, Idaho at the City Hall (6015 Glenwood Street); on May 7, 2014 from 11:00 a.m.-1:00 p.m. in Boise, Idaho at the Washington Group Plaza Training Room (720 Park Boulevard); on May 7, 2014 from 6:00 p.m.-8:00 p.m. in Caldwell, Idaho at the Caldwell Industrial Airport Hubler Conference Room (4814 E. Linden Street); and on May 8, 2014 from 6:00 p.m.-8:00 p.m. in Idaho City, Idaho at the Ray Robinson Community Hall (206 West Commercial Street). The Corps will provide notice to the public of additional opportunities for public input on the EIS during review periods for the draft and final EIS.

Issues to be analyzed in the EIS include, but are not limited to:

  • Effects to ESA listed bull trout above Arrowrock Reservoir;
  • Effects to fisheries in the South Fork Boise River;
  • Effects to hydropower generation facilities at Arrowrock Reservoir;
  • Effects to recreation in the South Fork Boise River;
  • Effects to cultural resources, including to Arrowrock Dam, which is listed on the National Register of Historic Places.

The Corps will serve as the lead Federal agency in preparation of the EIS. A decision will be made in the near future whether other agencies and/or tribes will serve in an official role as cooperating agencies or joint lead agencies. The draft EIS is scheduled to be available for public review in October 2015. The final EIS is currently scheduled to be available for public review in summer 2017.

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Andrew D. Kelly,

LTC, EN, Commanding.

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[FR Doc. 2014-09321 Filed 4-23-14; 8:45 am]