Technical Memorandum No. ENV-2025-074: Upper Klamath River Basin Surface Water Hydraulic Modeling Report from the Klamath River Basin Revised Natural Flow Study

Description

This report documents the hydraulic analyses conducted in support of the broader Klamath Natural Flow Study. Components of the hydraulic analyses needed for the prediction of daily streamflow estimates include the surficial movement and storage of water across the landscape. Methods and results presented here include: (1) area-capacity relationships for Upper Klamath, Lower Klamath, and Tule Lakes, (2) rating curves (relationships between water surface elevation and discharge) at the downstream hydraulic control of Upper Klamath Lake under 1981–2020 and pre-development conditions, and (3) pre-development streamflow losses through the Lost River Slough and streamflow exchanges with Lower Klamath Lake. Results within this report are not actual daily predictions, but information to be used to calculate daily streamflow. Regarding water storage, surficial water area and storage have decreased greatly from pre-development to 1981–2020 conditions. The modeling of the hydraulic control at Upper Klamath Lake indicates that pre-development water surface elevations as compared to 1981–2020 conditions would be higher at low streamflow and lower at high streamflow. Finally, pre-development modeling between Link River and Keno, Oregon indicates that the Klamath River only diverted a portion of streamflow through the Lost River Slough to Tule Lake at flood discharges. The connection of the Klamath River with Lower Klamath Lake was dynamic and bi-directional, but streamflow exchanges were likely relatively small due to the self-regulating negative feedback preventing extreme streamflow exchanges in either direction. The results presented within this report were delivered to RiverWare as look-up tables to aid in the calculation of daily streamflow.

Resources

Name Format Description Link
33 "Technical Memorandum No. ENV-2025-074: Upper Klamath River Basin Surface Water Hydraulic Modeling Report from the Klamath River Basin Revised Natural Flow Study" as a PDF file https://data.usbr.gov/rise/content-rise-public/rise/catalog-item/binary/KlamathBasinRevisedNFS_SurfaceWaterHydraulicModeling_2025Sept.pdf
21 Landing page for "Technical Memorandum No. ENV-2025-074: Upper Klamath River Basin Surface Water Hydraulic Modeling Report from the Klamath River Basin Revised Natural Flow Study" https://data.usbr.gov/catalog/8528/item/133876

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  • surface-water
  • modeling
  • natural-flow-study

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