Way Minimum Flow Variance Hydro FERC Project: Analysis and Compliance

Strategic Insights -

The Way Dam project (FERC No. 1759) has a minimum flow requirement that varies by time of year, with compliance measured at the USGS gage No. 04062500, located on the Michigamme River below the Hemlock Falls project (FERC No. 2074). The project's licensee must operate in a run-of-river mode, maintaining the reservoir elevation and minimum flow requirements as specified in Articles 402 and 403 of the license. On July 14, 2025, a tree fell on the distribution line, causing the generating unit at Hemlock Falls to trip offline, resulting in a 14-minute period where the minimum flow requirement was not met.

Key Takeaways:

  • The Way Dam project has a minimum flow requirement that varies by time of year, with compliance measured at the USGS gage No. 04062500.
  • The licensee must operate in a run-of-river mode, maintaining the reservoir elevation and minimum flow requirements as specified in Articles 402 and 403 of the license.
  • On July 14, 2025, a tree fell on the distribution line, causing the generating unit at Hemlock Falls to trip offline, resulting in a 14-minute period where the minimum flow requirement was not met.
  • The lowest flow of 298 cfs occurred at 1515 CDT hours, and the headwater elevation at Hemlock Falls remained in compliance throughout the event.
  • The licensee shall restore the required minimum flow within 30 minutes of a power outage or automatic plant shutdown.
  • The licensee shall notify the Commission and the agencies as soon as possible, but no later than 10 days after each incident where the minimum flow requirements are modified or not met.

Statistics:

  • The minimum flow requirement for the Way Dam project varies between 250 cfs for August 1 through April 30, 400 cfs for May 1 through June 30, and 300 cfs for July 1 through July 31.
  • The lowest flow of 298 cfs occurred at 1515 CDT hours on July 14, 2025.
  • The licensee must maintain the reservoir surface elevation between 1,335.2 feet NGVD and 1,337.6 feet NGVD at all times, with specific elevations required during periods of generation and non-generation.
  • The time required to fill the Hemlock Falls impoundment to restore downstream flow impacted the required minimum flow of 300 cfs at the downstream USGS gage for a period of about 14 minutes.

Sources:

  • FERC Project No. 1759 (Way Dam project)
  • FERC Project No. 2074 (Hemlock Falls project)
  • USGS gage No. 04062500 (Michigamme River near Crystal Falls)
  • Agreement, section 3.1.2.1, filed May 15, 1997 (Wilderness Shores Settlement Agreement)
  • Agreement, section 3.1.2.2, filed May 15, 1997 (Wilderness Shores Settlement Agreement)