| The dams are gone, but salmon and natural flow study are back |
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Tim Clarkin—Bureau of Reclamation Technical Service Center; Marketa McGuire—Bureau of Reclamation Technical Service Center; Kelleen Lanagan—Bureau of Reclamation Technical Service Center; Vik Stromberg—Bureau of Reclamation Klamath Basin Area Office |
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ABSTRACT |
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The Klamath Natural Flow Study seeks to understand what daily streamflow throughout the Klamath River Basin might have been under 1981-2020 climate conditions in the absence of major development over the past 150 years. Daily natural flow estimation involves use of process models to quantify recharge and discharge to groundwater, consumptive uses, evaporative losses, and hydraulic changes in the basin. The largest dam removal effort in American history was completed in 2024 on the Klamath River, which consisted of removal four hydroelectric dams and return of salmon runs to 400 miles of habitat that had been cutoff for over 60 years. This study will provide foundational science to understand changes in the basin and will likely inform future water management policy, Endangered Species Act (ESA) consultations, water rights adjudication, and litigations. RiverWare plays a central role in this study, effectively combining observed data and output from relevant process models to estimate natural streamflows through mass balance calculations. Some interesting elements of the Klamath Natural Flow Study RiverWare model include:
- Adopting a two-step modeling approach facilitated by scripts: first simulating 1981-2020 conditions to solve for hydrologic inflows and, second, using those inflows as input for simulating pre-development conditions.
- Filling Streamflow data where data is missing or discontinuous.
- Handling of changing reservoir characteristics to account for damming of existing natural lakes to form reservoirs, and disconnection and reconnection of portions of Upper Klamath Lake over time.
- Integrating results from relevant process models under 1981-2020 conditions and pre-development conditions.
This presentation serves as a general update on the status of the ongoing project and opportunity to share findings and solicit feedback from the broader community of RiverWare users. |
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