Kerr Dam & Lake Level News

Kerr Dam at 50,000 cfs  -photo by Karen Swan

Lake Level Going Down

Unfortunately, with the snowpack virtually gone and record low precipitation this spring, it will be difficult to maintain the summer lake level.

NorthWestern Energy is managing flows through the dam according to the draft Drought Management Plan (DMP) developed by PPL-MT in 2002.  They have been releasing water at the dam to achieve the minimum river flows required by the FERC license for the dam.  The license requirements for river flows and lake levels conflict during significant droughts, which is why a drought management plan is needed.

NorthWestern Energy requested and received on July 2 a variance from the license reuqirement for minimum flow releases from Kerr Dam according to the steps outlined in the draft DMP (see news release and letters to the Federal Energy Reguatory Commission and Dept. of Interior).  In addition, the Bureau of Reclamation agreed to increase outflows from Hungry Horse Dam.  NorthWestern projects the lake level will remain at or slightly above 2892 feet through July and August.

You can view graphs showing actual (through July 8) and projected May-July 2015 lake levels compared to lake levels during the last big drought in 2001 plus outflows in the river below the dam.

NorthWestern Energy (and previous PPL MT) Kerr Dam and Flathead Lake level updates:

2014 and 2015 Updates

July 23, 2015 Update
July 2, 2015 Update

June 16, 2015 NorthWestern Energy Letter to FERC and DOI
May 2015 Update
April 2015 Update
March 2015 Update
February 2015 Update
December 2014 Update
November 2014 Update
October 2014 Update
September 2014 Update
July 2014 Update
June 2014 Update
May 2014 Update
April 2014 Update
March 2014 Update
February 2014 Update
January 2014 Update

2011 - 2013 Updates

September, 2013 Update
October, 2013 Update
June, 2013 Update

May, 2013 Update

April, 2013 Update

March, 2013 Update
February, 2013 Update

January, 2013 Update
December, 2012 Update

November, 2012 Update

July, 2011 Update
June, 2011 Update
May 26, 2011 press release
on Flathead Lake level projection
May, 2011 Update
March, 2011 Update

February, 2011 Update

January, 2011 Update

June & July, 2011 Updates

July 7

Sustained summer temperatures are finally here and the mount

ain snowpack is melting, keeping streams and rivers high. The forecasts show water flow into Flathead Lake will gradually diminish over the next week, but not by a lot. Hungry Horse Reservoir is now 10 feet below full pool. Inflow into the reservoir

is at 20,000 cfs and discharge from Hungry Horse Dam is 9,000 cfs. Flathead Lake is currently at 2,892.08' (at 12:15 pm) and predicted to gradually increase.

June 23
The silver lining in our cold, damp spring is that, in spite of the rain, the snow melt and runoff have been relatively slow and gradual so far. It now looks unlikely that Flathead Lake will exceed full pool. The Northwest River Forecast Center's 4-10 Day Trend Forecast predicts a peak flow into the lake of around 60,000 cfs on June 25-26 and the lake level reaching 2892.5 on June 26. However, a flood watch remains in effect for all three stems of the Flathead River from Friday June 24 through Sunday morning. Tributaries may also approach flood stage through the weekend.

June 15
The lake level is at 2891.99 this morning. Kerr Dam flood gates remain wide open. Net inflows are around 6,000 cfs. At this rate, the lake level would rise a foot in 10 days. Hungry Horse Dam is discharging 8,000 cfs and the reservoir level is rising almost 2 feet per day (currently about 38 feet below full pool). A tremendous amount of water is coming down the Stillwater and Swan Rivers. Groundwater in the shallow aquifer connected to the Flathead River appears to be rising and farm fields in this area are saturated. And there is still a lot of snow in the mountains. Scroll down for more information and links.

June 9
PPL Montana's June 9 press release projects a "moderate potential for Flathead Lake to exceed full pool by up to six inches from approximately mid-June to the first week of July."  See the June, 2011 Update for the full news release and our June lake level summary (next) for more information.

Corps predicts Flathead Lake will exceed 2893’ in June

by James Conner for the Flathead Lakers  • June 4

Flathead Lake probably will exceed full pool by almost a foot in mid to late June. That prediction comes from the U.S. Army Corps of Engineers, which estimated on May 25 that the lake will peak at 2893.91 on June 18.

The reason? Record snowpack and delayed snowmelt, augmented by rain, will produce lake inflows greater than the outflows at Polson, causing the lake to rise until an equilibrium is reached at just under 2894 feet elevation Somers Datum (more on the Somers Datum below). The date and level of the peak could vary from the Corps’ prediction. And we do not yet know the predicted duration of the excursion above full pool. Click here to read the rest of this summary.

Flathead Lake levels and Kerr Dam outflows

by James Conner for the Flathead Lakers

Flathead Lake's outlet channel is narrow and shallow. At low lake levels, the rate of outflow is less than the 15,000 cfs capacity of Kerr Dam's turbines. When Flathead Lake reaches 2885.80, the discharge from the lake matches the dam's turbine capacity. As the lake rises higher, the channel's capacity increases, as displayed by the graph below and the Excel table (click here to download table).

If the inflows to Flathead Lake are greater than the outflows, the lake rises. During the spring runoff (usually May through June), the inflows to the lake can be much greater than the outflows, even when Kerr Dam is wide open and not holding back any water.

That last happened in 1964, when the great flood in early June pushed the lake to 2894 for a week. During that flood, the Flathead River peaked at 176,000 cfs, and would have peaked at more than 220,000 cfs had not the South Fork's flows been stored in Hungry Horse Reservoir.

The lake will rise one foot in one day with net inflows of 64,000 cfs. Smaller net inflows fill the lake more slowly.

Links to Streamflow, Snowpack, and Flood Information

Northwest River Forecast Center Trend Forecast for Flathead Lake & Kerr Dam

Northwest River Forecast Center River Conditions Summary for the Flathead River and its 3 forks

Northwest River Forecast Center Peak Flow Forecasts - Flathead River at Columbia Falls

USGS Montana Flood Frequency & Basin Characteristic Data

National Weather Service Hydrologic Outlook - Flathead River at Columbia Falls Stage Height

Noisy Basin Snowtel Site:  Information & reports  All Snotel Sites

Flathead Watershed Sourcebook: Floods, Flooding Effects on Flathead Lake, Analyzing Flooding

Graphs of flood/high water years (flows of N Fork + M Fork Flathead River):  1947, 1948, 1950, 1954, 1964, 1974, 1975, 1991, 1997, mean daily stream flow April-July

NRCS Streamflow Forecast Probability Chart

More links: realtime lake levels & streamflow data. Or see menu on left side of this page.

 

2010 PPL Montana Updates

November, 2010 Update
October, 2010 Update

September, 2010 Update

July, 2010 Update

June, 2010 Update

May, 2010 Update

March, 2010 Update

February, 2010 Update

January, 2010 Update

 

Boat Ramp Map file

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