Kodiak Electric Association, Inc. Submits Notification of Deviation from Instream Stream Flow Requirements for Terror Lake Hydroelectric Project

Strategic Insights -

The Kodiak Electric Association, Inc. (KEA) has submitted a notification to the Federal Energy Regulatory Commission (FERC) regarding deviations from Article 43 requirements under FERC License No. 2743 for the Terror Lake Hydroelectric Project located in Kodiak, Alaska. The notification outlines low flow deviations in the lower Terror River, which were primarily due to unstable hydrology and technical issues with USGS gauging instruments. KEA has taken steps to address these issues and minimize the impact on the environment.

Key Takeaways:

  • The Terror Lake Hydroelectric Project has experienced 7 instances of low flow deviations in the lower Terror River between March 20 and September 18, 2025.
  • The deviations were primarily caused by unstable hydrology, which resulted in a multi-hour delay in the passage of water from the Project's point of release to the point of compliance.
  • Technical issues with USGS gauging instruments, including unstable data output due to wave action, contributed to the deviations.
  • KEA has not observed any adverse environmental effects and has not received any comments from resource agencies or other interested parties regarding the deviations.
  • The Project's valve control response time and USGS data transmission delay may need to be improved to better accommodate changing river flows.
  • KEA will continue to examine long-term solutions for improving the automated valve system and its ability to respond to changes in downstream river levels.

Statistics:

  • 46 square miles: the approximate size of the Terror River watershed.
  • 8 river miles: the distance from the Terror Lake dam to the USGS gauging station.
  • 4,200 feet: the elevation change from the Terror Lake dam to the USGS gauging station.
  • 7.5%: the maximum allowed deviation from instantaneously required flow under Article 43.
  • 150 cfs: the required daily average flow level in the lower Terror River.
  • 13%: the instantaneous flow deviation on September 11, 2025.
  • 16%: the instantaneous flow deviation on August 29, 2025.
  • September 11, 17, and 18, 2025: dates when daily average flow in the lower Terror River fell below the required level of 150 cfs.
  • April 11 and August 28-29, 2025: dates when instantaneous stream discharge fell below 7.5% of the required flow.

Sources:

  • USGS letter dated September 22, 2025.
  • Excel file containing discharge data for USGS stream gauging station No. 15295700.
  • Article 43: Notification of Deviation from Instream Stream Flow Requirements, FERC License No. 2743.