Anderson Ranch Dam

Anderson Ranch Dam, seen from the road in July 2020.

BOISE — The Idaho Water Resource Board and Bureau of Reclamation discussed a proposal on May 21 to delay federal environmental approval for the proposed 6-foot raise of Anderson Ranch Dam to allow for completion of additional analysis needed to address critical questions about project construction.

The discussion occurred during the regular May bimonthly meeting of the Idaho Water Resource Board.

The project will stay on track to meet federal WIIN Act requirements which require a cost-share agreement between Reclamation and a partner or partners capable of funding the non-federal project costs, as well as initiation of project final design by Dec. 16, officials said.

With this modified schedule, a final environmental impact statement and record of decision for the Boise River Feasibility Study are expected in 2023, following detailed design analysis that will fully define any reservoir-restriction requirements during construction, Bureau of Reclamation officials said.

The additional analysis and design work will provide the critical additional information required to complete the final environmental impact statement for the board and water users to evaluate refined project costs, and to inform the decision whether to proceed with construction, officials said. Products also will include revised construction timelines and options to mitigate potential impacts to existing Anderson Ranch Reservoir water users during project construction, officials said.

“Pausing completion of environmental compliance activities will allow us to address critical issues raised during the public comment period while allowing design to proceed as scheduled, thereby maintaining the schedule for project completion,” said Bryan Horsburgh, Snake River area office deputy manager.

If built, the project would add 29,000 acre-feet of storage water to Anderson Ranch Reservoir. An agreement with the Board will allow the Bureau of Reclamation to initiate the next steps in project development to meet WIIN Act deadlines, but requires the water board to commit additional funds to cover the non-federal share of the design analysis costs.

The board voted to move forward with the contract-negotiation process under the modified project schedule.

“This is a really important project. We’ve got several more hurdles to clear but this will keep the project moving forward,” said water board Chairman Jeff Raybould.

In other actions, the IWRB heard from more than 10 people representing Elmore County and the Mountain Home community about the importance of finding more water for economic growth and sustainability. Speakers included Elmore County commissioners, Mountain Home City Council members, local legislators and local water users. They discussed the declining condition of the Mountain Home Plateau Aquifer and importance of securing additional water supplies to support existing agriculture and domestic users, and to allow new municipal and commercial growth in the area. They appealed to the board to consider expanding the Treasure Valley Ground Water Model that’s been under development for several years to include the Mountain Home area.

Terry Scanlan of SPF Water Engineering presented information about the aquifer conditions and recent efforts by Elmore County to perform ground water recharge and plan water supply projects. He noted that a better understanding of the underlying aquifer would help the local community make more informed water management decisions and help IDWR with water right administration. He encouraged the board to consider taking advantage of the existing Treasure Valley Ground Water Model development effort and technical modelling committee to expand the model into Elmore County and the Mountain Home area.

“Declining ground water levels are threatening the economy of Elmore County,” he said.

Ground water pumping exceeds aquifer recharge by 40,000 acre-feet, officials said, meaning the aquifer is being overdrawn by about 40,000 acre-feet per year, forcing farmers and domestic users to deepen their wells.

Elmore County Commissioner Bud Corbus stressed the need for support in order to sustain and grow the community.

In other action, the water board:

n Received a presentation from IDWR hydrologists about the Bear Lake storage analysis, performed in cooperation with the states of Utah and Wyoming and PacifiCorp. The analysis included development of a planning model to evaluate whether additional water can be stored in Bear Lake, potential impacts to Gentile Valley landowners downstream resulting from flood releases, and impacts to the Bear River, Great Salt Lake, and PacifiCorp power production.

Board members recognized there will be ongoing coordination between the three states, local land owners, and PacifiCorp. Officials also noted that options for cloud seeding to benefit Idaho water users in the Bear River basin are also being explored in response to House Bill 266, approved by the 2021 Legislature, which encouraged the board to expand cloud seeding into new basins.

n Approved a $20,000 loan to the Point Springs Grazing Association to allow the association to drill a new well for stock water use.

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