Lake Sakakawea is rapidly approaching a complete freeze.
If the massive reservoir is officially declared frozen-over prior to Dec. 20, which appears to be a certainty, it will mark the shortest season of open water in the history of the state's largest body of water.
On Thursday, much of the reservoir was covered in ice but there was some open water, primarily in the area immediately above the dam. The water there is some of the deepest in all of Lake Sakakawea and is considered the last portion of the reservoir to freeze each year. From a nearby overlook leading to the dam's intake structure, engineers from the Garrison Dam power plant make daily observations of ice formations and remaining open water.
Operators in the Garrison Dam power plant control room annually record when Lake Sakakawea freezes and thaws. This year’s Lake Sakakawea freeze is likely to become one of the earliest on record.
"That is where we normally check because you can see most of the area from there," said Jeff Pochant, Garrison Dam power plant. "That's the last area to freeze, so that's where we declare Lake Sakakawea iced over when it happens."
The engineer making the observation relays the information to the Garrison Dam power plant control room. There the date of the official freeze and the elevation of the reservoir is recorded. Records of Lake Sakakawea freezing and thawing have been kept since 1961.
"There's no real importance to it," said Pochant. "All the fishermen want to know when it is frozen over for ice fishing. That's about it."
Earliest freeze dates
1 Nov. 30, 1985
2 Dec. 11, 1961
3 Dec. 14, 2000
4 Dec. 15, 1989
5 Dec. 17, 2008
Latest freeze dates
1 Jan. 18, 2012
2 Jan. 15, 1987
3 Jan. 16, 2000
4 Jan. 12, 1976
5 Jan. 12, 1998
Latest ice out dates
1 May 17, 1979
2 May 14, 1970
3 May 13, 2013
Earliest ice out dates
1 March 27, 2012
2 March 31, 2000
3 April 1, 1990
While the freezing over of the reservoir has no impact on power plant operations, the date of the annual freeze is of interest to those who enjoy tracking weather trends. For example, the eventual date of this year's freeze will take on added significance if it occurs prior to Dec. 18. That's because the reservoir wasn't declared ice free until May 13 of this year, the third latest ice date out on record.
The fewest amount of days Lake Sakakawea was ice free was 220 days from May 14 to Dec. 21, 1970. That record is all but certain to fall this month. If Lake Sakakawea is declared officially frozen over on Dec. 18, it would mean the lake was ice free only 219 days during 2013. There's a
possibility that Lake Sakakawea will freeze over much earlier than that date.
"It would have froze a weekend ago if the wind wouldn't have been there," said Pochant. "Yes, it would probably have froze over."
According to Pochant, the temperature of the water passing through the power plant earlier this week was 33 degrees. That water is taken from the bottom of the reservoir. At the surface, where ice formation begins, the temperature is colder. However, complete freeze-up can be delayed by wind and wave action and, to a lesser extent, by activity from waterfowl such as ducks and geese.
"If the temperature stays cold like it is supposed to, it could freeze over in a day or two with no wind," said Pochant.
When Lake Sakakawea does freeze this winter, it seems destined to be one for the record books. The earliest recorded freeze for the reservoir is Nov. 30, 1985, the only Nov. freeze on record. The third earliest freeze occurred on this date in 2000. Numbers four and five on the list are Dec. 15, 1989, and Dec. 17, 2008.