A 2026 Spring HFE

High Flow Experiment- Spring 2026

2026 Spring High Flow Experiment Snapshot

DOI Decision

DATE: June 5, 2026 
TO: AMWG, TWG, and Planning and Implementation Team Members
FROM: Wayne G. Pullan, Regional Director, Upper Colorado Basin Region, Bureau of Reclamation 
SUBJECT: Decision Regarding Spring 2026 HFE
Dear AMWG, TWG and Planning and Implementation (PI) Team Members,  
I am writing to notify you that Reclamation will not implement a spring High Flow Experiment (HFE) from Glen Canyon this month. This decision reflects the mixed support expressed by members of the PI Leadership Team. In accordance with the revised HFE protocol, the sediment mass balance will roll over into the next accounting period beginning July 1, 2026, and an HFE will be reconsidered for potential implementation in fall 2026. I would like to extend my sincere appreciation to the PI Technical and Leadership Teams, as well as the Grand Canyon Monitoring and Research Center (GCMRC), for their dedication and contributions in supporting a well-informed decision.  
Consideration of a cool mix flow remains pending, and we anticipate sharing a decision in the coming weeks. Thank you for your patience as we work through these important and complex issues.  
Wayne G. Pullan, Director  
Upper Colorado Basin Region  

Assessment of Resources consistent with the 2016 LTEMP ROD and 2024 LTEMP SEIS ROD (all resources were evaluated for a fall HFE)

Nonnative Invasive Species

Green Sunfish (Lepomis cyanellus)

Brown Trout (Salmo trutta)

Smallmouth Bass (Micropterus dolomieu)

Other Nonnative Invasive Fishes

SUPPORTING DOCUMENTS

• 2026 Spring HFE Tech Report

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