Required Minimum Flows for the
Flathead River Below Kerr Dam

Summary

After Kerr Dam began operations, flows in the Flathead River below the dam site changed significantly. Spring flows were curtailed to the extent necessary to fill the lake -- only the threat of flooding in the Flathead was cause for spilling water during the runoff season. Fall and winter flows were increased as the lake was drawn down. Because the dam was used for peaking and load following, hourly and daily changes in discharges often were dramatic. By the late 20th century, the reach below the dam had become, in the words of fisheries researchers, a "biological desert." When the license for the dam was renewed, the mitigation plan included restrictions on minimum flows and flow ramping rates. The required minimums approximate the lowest recorded pre-dam flows, and are displayed in graphs below.

License Requirements

Article 56. The licensee shall maintain releases at or above the following instantaneous minimum flow, in cubic feet per second (cfs) on a continuous basis as measured at the U.S. Geological Survey Polson gage, provided that the passage of minimum flows from Flathead Lake downstream is not limited by the natural channel capacity immediately upstream of the Kerr Dam. The licensee shall manage the project in a manner that limits the occurrence of such channel capacity limitations.

Minimum Flow Requirements Dates Minimum Flows August 1 to April 15 Continuous at 3,200 cfs April 16 to April 30 Increased from 3,200 cfs to 5,000 cfs at 120 cfs per day May 1 to May 15 Increased from 5,000 cfs to 12,700 cfs at 510 cfs per day May 16 to June 30 Continuous at 12,700 cfs July 1 to July 15 Reduced from 12,700 cfs to 6,400 cfs at 420 cfs per day July 16 to July 31 Reduced from 6,400 cfs to 3,200 cfs at 200 cfs per day.

The minimum instream flows may be temporarily modified by operating emergencies beyond the control of the licensee, or for short periods upon written approval from the Secretary of the Interior.

Article 57. The licensee shall operate the Kerr Project in accordance with the following between-day restrictions on flow variations as measured at the U.S. Geological Survey Polson gage, escept as necessary to meet flood control requirements imposed by the U.S. Army Corps of Engineers under the Memorandum of Understanding with Montana Power Company (as amended in 1965), or as may be further amended by the U.S. Corps of Engineers subsequent to approval of the Secretary of the Interior.

Maximum Between-day Flow Changes Mean Flow (cfs, 24-hour average) Maximum Change in Flow (cfs) Less than 5,000 500 Between 5,000 and 10,000 1,000 Between 10,000 and 20,000 2,500 Between 10,000 and 40,000 5,000 Between 40,000 and 60,000 10,000

The between-day restrictions on flow variations may be temporarily modified if required by operating emergencies beyond the control of the licensee, or for short periods upon prior written approval from the Secretary of the Interior.

Article 58. The licensee shall operate the Kerr Project in accordance with the folloing hourly maximum allowable ramping rates, except as necessary to meet flood control requirements imposed by the U.S. Army Corps of Engineers under the Memorandum of Understanding with Montana Power Company (as amended in 1965), or as may be further amended by the U.S. Corps of Engineers subsequent to approval of the Secretary of the Interior.

Maximum Allowable Ramping Rates Mean Flow (cfs, 24-hour average) Ramping Rate Between 3,200 and 7,500 250 cfs/hour 7,500 or greater 1,000 cfs/hour

The hourly ramping rates may be temporarily modified if required by operating emergencies beyond the control of the licensee, or for short periods upon prior written approval from the Secretary of the Interior.

Article 59. The Montana Power Company [Montana Power's interest was purchased by PPL MT] and the Confederated Salish and Kootenai Tribes (licensees) shall cooperatively develop and initiate a site-specific ramping rate study as part of the adaptive management planning process. The study shall incklude a two-year phase assessing effectiveness of improving physical habitat and the establishment of a biological baseline. Within six (6) months of floowing completeion of the first two years of the study, the licensees shall submit to the Secretary of Interior (Secretary) a report and recommendations, based on the results of the first two-year phase of the study, on proposed revisions to the existing ramping rates. To the extent the Secretary approves revisions to the existing ramping rates, the licensee shall operate under the revised ramping rates upon issyuanceof an order by the Commission amending the license as provided by the Secretary. The second phase of the study shall focus on the biological response to the existing or revised ramping rates. At the end of the ten years following the initiaton of the ramping rate study, the licensees shall subject to the Secretary a report and recommendations, based on the results of the study, on proposed revisions to the existing ramping rates. To the extent the Secretary approves the proposed revisions to the existing ramping rates, the licensees shall operate under the revised rampingrates upon the issuance of an order by the Commission amending the license as provide by the Secretary.

Article 60. The licensees, in consultation with the U.S. Army Corps of Engineer[s], the Bureau of Reclamation, the Bureau of Indian Affairs, and the Montana Department of Environmental Quality, shall develop and implement a drought management plan for Flathead Lake. The drought management plan shall include, but not be limited to, provision for re-evaluation and adjustment of Flathead Lake flood control requirements and other provisions necessary to facilitate compliance with lower Flathead River minimum instream flow requirements designated by the Secretary of the Interior.

Article 61. The licenssees shall consult with the U.S. Bureau of Rellamation on a weeky basis from April 20 to August 31 and on a biweekly basis the remainder of the year regarding the anticipated releases from Hungry Horse Reservoir. On the first Monday (workday) of each week or biweeky period, the licensees shall request notification from the Bureau of Reclamation of the Hungry Horse projected release(s) for the period of time commencing on that day and extending for the subsequent 21 days.

The licensees shall, in a timely manner and within the maximum allowable changes in flow discharge rates set for the Kirr Project, coordinate operations with the Hungry Horse Project releases. To facilitate the coordinated operations on Kerr and Hungry Horse, the licensees may participate in the Technical Management TReam process pursuant to the National Marine Fisheries Service Biological Opinion(s) on operation of the Fideral Columbia River Power System (or successor process) to the extent allowed by Federal law.

Article 62. The licensees shall provide to the Secretary of the Interior annually oon or about May 1, but no later than May 10, an annual operational schedule to be supplemented on a monthly basis. The annual schedule shall include month-end estimates of water surface elevation at Flathead Lake and estimates of monthly discharges from Kerr Dam. The monthly supplement shall include a report of actual operations over the previous month and shall include daily water surface elevation at Flathead Lake and spill and releases at Kerr Dam. The annual schedule and monthly supplements can be based on hydrologic and operational information compliled by other cooperating agencies. The operational schedule shall take into account forecasted inflows to Flathead Lake, flood control and recreational requirements in Flathead Lake as well as minimum flow requirements at Kerr Dam.

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