The runoff run-up
Area prepares for flood threat; Record flooding likely downstreamBy KIM FUNDINGSLAND, Staff Writer kfundingsland@minotdailynews.com
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Fact Box
Flood emergency declared
Citing very high soil moisture content in Ward County, the significant potential for severe spring flooding and the potential damage to public and private property, Ward County has issued a Flood Emergency Declaration. Bruce I. Christianson, chairman of the Ward County board of commissioners, announced the declaration Monday.
Minot Mayor Curt Zimbelman said the city would also consider an emergency declaration and present it to the city council on April 6.
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Souris River probabilistic forecast
Town..............Flood stage....% likelihood
Sherwood....18 feet...22.5 ft. .....80%
Foxholm......10 feet...13 ft. ........90%
Sawyer........22 feet...24 ft. ........95%
Logan..........34 feet...36 ft. .......95%
Bantry.........11 feet...14 ft. ........99%
Westhope.....10 feet...17.5 ft. .....99%
Minot and Ward County officials, spurred by the latest runoff forecast for the Souris River Basin, held a well attended press conference Monday at the First District Health Unit to reveal their preliminary plans should a flood threat materialize. Minot Mayor Curt Zimbelman opened the informational session.
"We are holding this meeting, not to alarm anyone, but to keep everyone informed what the city and county are doing in preparation for anything that may happen," said Zimbelman. "There are so many variables right now that it is difficult to determine what will happen."
After watching flooding in virtually every other region of the state, it appears attention could soon be turning to the Souris River Basin where huge amounts of snowfall have yet to meet warm temperatures. As each day passes without significant runoff, it increases the odds that summer-like temperatures will arrive and trigger a rapid snowmelt. For residents along all drainages in the Souris River loop, the waiting game to see what the runoff will bring has begun.
The latest National Weather Service probabilistic runoff forecast for the Des Lacs and Souris River Basins shows a marked increase from projections released March 13. While the Souris River is still expected to remain below flood stage at Minot and well below the levees protecting the city, downstream points are now facing a high probability of record flooding that could last for several weeks.
The National Weather Service cautions that probabilistic forecasts are based on existing conditions on the ground combined with 30 to 50 years of historical weather patterns and are released only to convey the percentage of flooding risk. Weather conditions can greatly influence snowmelt and significantly alter runoff projections. More precise flood forecasts are issued once runoff actually begins to enter drainage systems.
Among the attention getting numbers included in the latest outlook is the amount of water that is now expected to flow down the Souris River and across the North Dakota-Saskatchewan border at Sherwood. Flood stage at the Sherwood gauge is 17.99 feet. According to the latest outlook there is an 80 percent possibility that the Souris River at Sherwood will reach a level of 22.5 feet. The all-time high for the river at Sherwood was 25.8 feet, set in 1904. If flows exceed 20.7 feet, water would flow over two bridges near the gauging station and flood several square miles of farmland.
Two weeks ago it was expected that Sherwood would reach a maximum flow of 1,651 cubic feet per second with a total volume of 60,000 acre feet. The latest estimates show an 80 percent chance of 4,450 cfs. Even with the increased forecast, the Sherwood flow is not considered to be a serious or alarming development.
The Souris River coming down from Canada drains into Lake Darling and is backed up by the Lake Darling Dam. That facility has been operating about 7 feet below normal and currently has a water level measuring slightly over 1,590 feet. Spillway level at Lake Darling is 1601.8 feet. The reservoir currently has storage for 101,000 acre feet of water. Early estimates provided by the U.S. Army Corps of Engineers is that Lake Darling will likely raise to 1,598 feet. The record crest on Lake Darling occurred April 17, 1976, at 1,601.24 feet.
Snowfall this winter north of the border in Saskatchewan has been less than what has fallen over much of North Dakota. That means, barring any late spring storms, the primary concern is the snow on the ground in the drainages feeding the Souris Basin.
"Really, it's sort of good news. We've had some sunny days to lose water from the snowpack. It's probably as good as it could be for a forecast, nothing like Fargo or Grand Forks," said Doug Johnson, Saskatchewan Water Authority in Moose Jaw, Sask. "Nothing has really changed in the last several weeks. It'll have to warm up at night before we see any real runoff."
While it is apparent the Des Lacs River, which flows into and out of the Des Lacs NWR at Kenmare and joins the Souris near Burlington, will exceed flood stage it remains a troublesome river to predict and one in which the flows can be greatly effected by warm temperatures. The outlook gives the Des Lacs a 94 percent chance of topping out at 16.5 feet, one-half foot above flood stage. However, there's also a 70 percent chance the Des Lacs could top 18.25 feet.
Minot Public Works Director Alan Walter assured those in attendance at Monday's gathering that the city has already begun preparing for the possibility of water reaching the 100-year floodplain level.
"There's not a great chance of reaching that level, but we need to make plans," said Walter. "We will be lining up contractors to fill in low spots in dikes if that should become necessary. We will also have pumps ready to pump over the dikes if we have to do that."
Flood stage at Minot's Broadway Bridge is 1,549 feet. The most recent forecast calls for a 44 percent probability of reaching that level. However, the elevation of 1,549 is recorded in the river channel which is several feet below Minot's dike system.
Noting the substantial snowpack still existing in the area, Ward County Engineer Dana Larson warned of the high probability of flooding throughout the county.
"Anyone living along coulees or in lowlands should be aware of potential trouble," cautioned Larson.
Alan Reynolds, emergency manager for Ward County, said a number of preparations triggered by the latest outlook are already under way. Sandbagging operations will begin today at the old Burlington Fire Hall and at Arena 1 on the State Fairgrounds. According to Reynolds, the initial goal is to fill 50,000 sandbags to have on hand in case they are needed.
While Burlington, Minot and Velva have flood protection levees in place, other communities and rural residents face the prospect of dealing with a record or near-record flood event. Willow Creek rose in excess of 7 feet early Monday morning before topping out at 14.51 feet. An ice jam was said to be responsible for the sudden rise. Flood stage at Willow City is 10 feet. The weather service gives Willow Creek a 99 percent chance of exceeding 14 feet again when the snowmelt gets under way.
Another major tributary of the Souris River, the Wintering River, is given a 90-95 percent chance of recording a top-five all-time flow this spring. Flood stage on the Wintering at Karlsruhe is 7 feet. The weather service outlook warns of a crest in excess of 10 feet.
Along the Souris River downstream from Minot, Logan and Sawyer are expected to see river crests 2 feet or more over flood stage. The Souris is expected to top the 14-foot mark at the Bantry gauge where flood stage is 11 feet. Westhope, the last recording point on the Souris before it enters Canada, seems all but assured of a experiencing a massive flow of water.
According to the outlook, Westhope has a 99 percent chance of reaching 17.5 feet and more than a 50 percent chance of setting an all-time high. Flood stage at Westhope is 10 feet and the highest recorded level is 19.16 feet on April 20, 1976. If the current outlook proves true, flows at Westhope could reach 12,000 cubic feet per second. While those flows would result in considerable flooding of farmland and area roads, the city of Westhope would remain dry.
New forecasts for the Souris River and major tributaries are expected to be issued Friday by the National Weather Service. The Saskatchewan Water Authority will also be releasing new forecast numbers. That forecast could be released as early as Wednesday. Preliminary reports indicate that the expected amount of runoff entering North Dakota from Canada will change very little from earlier expectations.
Reynolds has scheduled another informational session for today at 1 p.m. at the Health Unit where several emergency agencies will detail their preparations for possible flooding. A joint city-county press conference is also scheduled for Friday afternoon for the purpose of discussing the expected new snowmelt outlook issued by the NWS.
