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Kerr Hydrologic Operation Update for Flathead Lake

May 29, 2015

Butte, Mont. – May 29, 2015 – Representatives from NorthWestern Energy (NWE), U.S. Army Corps of Engineers (Corps), Energy Keepers, Inc. (“EKI”), Bureau of Reclamation, Bureau of Indian Affairs, and Bonneville Power Administration conferred on May 15th regarding current and projected operation of the Kerr Project. The current outflow is about 12,700 cubic feet per second (cfs) and the lake elevation, as of May 29, was 2891.01 feet, which is 1.99 feet from full elevation of 2893.0 feet.

Consistent with our Federal Energy Regulatory Commission (FERC) license and associated drought management plan requirements, NWE is operating the Kerr project taking into account the May volume runoff forecasts for the May through July period, the forecast precipitation, the current snowpack and the current natural stream flows. Estimates using the current projected runoff forecast indicate that achieving the inflow necessary to fill the lake to 2893.0 feet by June15 may be questionable.  

On May 28th, the volume runoff forecast for Flathead Lake prepared by the National Weather Service for the May to July period is 62% of average, which has decreased from the 91% projection last month for the April to July period. The natural stream flow for the month of April was about 119% of average; however, the stream flow for May has been only 64% of average. The current snowpack level is only 55% of average for this time of year.  

After review, discussion and consultation with the Tribes, Corps, and Bureau of Reclamation, NWE notified FERC and the U.S. Department of the Interior (DOI) of possible drought conditions and the potential for NWE to seek a variance from our FERC license Article 43 (lake elevation) and Article 56 (minimum flow) if conditions persist or continue to diminish. Forecast conditions have improved slightly in the last few days. If conditions materialize as currently forecast, it is possible that there will be sufficient inflow to fill Flathead Lake by June 15, 2015; however, due to the lack of snowpack, the forecast is heavily dependent on precipitation to maintain both lake level and downstream Flathead River license required flows. While no variances may be ultimately required, NWE decided to provide the FERC and DOI, as well as other interested parties, advance notice of the potential need for a variance.

In March 2002, a drought management plan (“DMP”) was filed with the Secretary of the U.S. Department of Interior for approval. The department is currently conducting an environmental review of the proposed DMP and considering alternatives. A final DMP has not been issued. In the interim, the operation will continue to be evaluated and adjusted, as appropriate, in consultation with the parties involved and with consideration of the 2002 DMP criteria. If conditions dictate, an ad hoc consultation with the parties involved will occur prior to the next monthly call.

NorthWestern will issue future press releases regarding the Flathead Lake level on a timely basis as the refill period progresses over the next few weeks. 

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