Notification of Minimum Flow Deviation for Rio Hydroelectric Project

Strategic Insights -

Eagle Creek Hydro Power, LLC, has submitted a notification to the Federal Energy Regulatory Commission (FERC) regarding a minor deviation from the required reservoir elevation in the Rio Hydroelectric Project (FERC Project No. 9690). The deviation occurred due to a malfunction at Rio Dam, resulting in the reservoir elevation dropping below the minimum required elevation during the fish spawning season. Operations staff took measures to mitigate the deviation and minimize environmental impacts.

Key Takeaways:

  • Eagle Creek Mongaup (owners and operators of the Rio Hydroelectric Project) have notified FERC of a minor deviation from the required reservoir elevation in Rio Reservoir from June 27-June 30, 2025.
  • The deviation was caused by high flows and the failure of three flashboards in one bay of Rio Dam, resulting in a gradual decrease in reservoir elevation.
  • Operations staff increased releases from Cliff Lake to prevent further deviation and mitigate the impact on fish spawning season.
  • The reservoir elevation dropped below the minimum required elevation (813.2 ft) and reached a low of 812.2 ft on June 30, 2025.
  • No adverse environmental or other resource impacts were observed or reported due to the deviation.
  • Eagle Creek Mongaup has provided notification as required by Article 402 of the Project's FERC license.

Statistics:

  • The deviation occurred from June 27-June 30, 2025.
  • The reservoir elevation dropped below the minimum required elevation (813.2 ft) on June 27, 2025.
  • The lowest reservoir elevation reached was 812.2 ft on June 30, 2025.
  • The deviation was caused by the failure of three flashboards in one bay of Rio Dam, resulting in a gradual decrease in reservoir elevation.
  • No adverse environmental or other resource impacts were observed or reported.

Sources:

  • Eagle Creek Hydro Power, LLC - Rio Hydroelectric Project (FERC Project No. 9690) License Article 401- Notification of Minimum Flow Deviation (July 7, 2025)
  • Attachment 1 - Rio Reservoir Elevations (date, time, elevation)