1. How were the design modifications for Phase 2 determined?
Engineers worked through a variety of scenarios using advanced hydraulic modeling and analysis in order to assess the Phase 2 adjustable wave setup and understand the complex elements resulting in the unstable wave feature created by the initial design. They used the best available technology, hydraulic modeling, engineering analysis, hands on operating experience of City of Boise operations staff and more to determine the best path forward to create a more reliable feature that is functional in a variety of conditions and river flow levels. Modifications to the existing spillway gates will also be completed to provide more flexible flow control and offer a pass-through option for stray boaters.
2. What changes will be made to the Phase 2 at the Boise Whitewater Park?
- Modification of the spillway structure to split current 20-foot-wide Gate 5 and Gate 6 to create four, 10-foot-wide gates. This will provide increased flexibility for operations of the main spillway as well as providing a pass-through option for stray boaters
- Modification of the waveshaper to allow for downstream tailwater control making the waveshaper less sensitive to overall changes in flow rate. A fully submerged downstream gate will allow our wave technicians the ability to increase tailwater depth and stabilize the wave feature
- Running additional air lines and wiring for the replacement spillway gate and submersible wave structure gate
- Waterproof vault components for flood resiliency and reduced maintenance needs
- Add a plunge pool downstream of the spillway gates to increase safety for stray boaters
- Mitigate leakage associated with the fish ladder structure on the left riverbank
3. Why are these design modifications necessary?
The original Phase 2 adjustable wave design does not create a predictable and consistent wave feature suitable for a variety of users. Due to its intensity and unpredictability, modifications are needed to create a more user-friendly experience. This will reduce the amount of staff time dedicated to the maintenance and monitoring of the wave feature, while creating a more reliable experience similar to what users have come to expect at the Phase 1 wave upstream from Phase 2.
4. Why hasn’t work started at Phase 2 of the whitewater park (Winter 2023/Winter 2024)?
Warm, wet weather and above average snowfall in January 2024, combined with longer than expected agency review timelines related to the permitting process, have created a unique situation that unfortunately pushed the modifications project to the Winter 2024/Winter 2025 season. We understand this is most likely a frustrating update for whitewater enthusiasts and appreciate your continued patience as the Boise Parks and Recreation Department works with engineers to shift the project timeline and inform users to help adjust expectations in 2024.
5. What can users and park visitors expect to see happening at Phase 2 during the winter (2024/2025)?
Construction crews will be working in the riverbed and visitors will see an area where water is diverted around the construction site. Construction equipment will be staged at Esther Simplot Park adjacent to the Phase 2 adjustable wave. Crews will follow all necessary safety and environmental protocols while completing these park modifications. A Greenbelt closure is anticipated throughout construction and will be signed appropriately.
6. What’s the timeline for completion?
Construction mobilization is now expected to begin in November 2024 with maintenance modifications expected to wrap up in the spring of 2025.
7. What will happen at Phase 2 during Summer 2024?
This modifications delay means Boise Parks and Recreation wave techs plan to hold monitored sessions at Phase 2 of the whitewater park again during the 2024 summer season. Details about times and days the wave will be operational will be announced at a later date. Our team will do its best to accommodate a variety of whitewater enthusiasts as conditions allow. It’s important to remember that first and foremost, the Boise Whitewater Park wave features serve as an important tool for water management, and the city must meet its water right requirements and the irrigation needs of the Thurman Mill Irrigation District.
8. Once the design modifications are completed (now expected in 2025) what will the user experience be like at Phase 2?
The Boise Parks and Recreation Department will determine this once the proposed modifications are completed. The goal of this project is to provide a more predictable wave for users to practice in without the need for monitored sessions with wave operators on site whenever river flows allow the wave to be operable. Just like the implementation of Phase 1 of the Boise Whitewater Park, it is expected to take several years for city wave techs to learn how to manipulate the new Phase 2 waveshaper gate, read river flows, and adjust on site to create various recreational experiences based on a variety of external factors.
9. Are modifications planned for any of the downriver features from the Phase 2 adjustable wave?
No adjustments are planned at other Phase 2 in-river structures at this time. The Boise River is a wild and scenic river that experiences streambed fluctuations and more each season. The project team will be closely monitoring for any impacts to downstream features to see if future modifications are necessary.
10. Will any of the planned modifications at Phase 2 affect the Phase 1 adjustable wave feature?
No, engineers do not anticipate changes to the Phase 2 adjustable wave feature to affect the Phase 1 wave feature located upstream at the park.