Klamath River Renewal Project - Dam Breach Analysis Used for Designing the Final Breach of the Iron Gate Dam
Authors: Daniel Adria1, Violeta Martin1, Nick Rong1, Katrina Wechselberger1
Conference: CDA 2025 Annual Conference and Trade Show
Date: September 29 - October 1, 2025
1 Knight Piesold Ltd., Vancouver, BC, Canada
ABSTRACT
The Iron Gate Dam (IGD) is the most downstream dam of the four facilities of the Klamath River Renewal Project (Nistor et al. 2025). It was partially removed with conventional deconstruction techniques. Due to site and drawdown schedule constraints, the final remaining portion of the IGD had to be breached with a head difference of approximately 23 ft (7 m). The assessment of the planned breach and the final IGD reservoir release is presented in this paper. The range of peak outflows during the intentional breach phase was assessed for variable inflow conditions with the goal to establish the most sensitive and limiting breach parameters for safe final breaching and reservoir release. The design of the breach plug and breach channel through the remaining IGD dam incorporated the findings from the breach analysis and included a predefined cross sectional geometry and placed riprap, with the goal to have a peak breach outflow within the allowable flow limits. The final breach was initiated on August 28, 2024. The breach plug slowly eroded, requiring encouragement from long-arm excavators. The full river flow was discharging through the breach by the end of the day. The peak discharge recorded at the USGS gage downstream of Iron Gate Dam was well within the allowable flow limits. Overall, the planned breach was successful due to the breach analysis completed in the design phase.
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