High water ahead
FOXHOLM A stubborn storm dumped record rainfall throughout the region this past weekend, primarily over the saturated and vulnerable Souris River Basin.
The result of the deluge was apparent almost instantly as rapid runoff tore through farm fields, filled ditches, flooded roadways and triggered the National Weather Service to issue flood warnings at multiple locations. With water on the rise, reservoirs on the Souris either began releasing water or making plans to do so within hours.
The North Dakota Department of Transportation reported that water surged over both the northbound and southbound roadways on U.S. Highway 83 near Coleharbor and over North Dakota Highway 256 south of Antler. Divide County emergency management closed all township and county roads east of N.D. Highway 42 due to heavy rainfall and poor road conditions. At least 16 communities in southern Saskatchewan declared a state of emergency due to the seemingly endless rainfall.
The brunt of the slow moving storm was felt in earnest Saturday. Reports from NWS cooperative observers measured rainfall including 5.5 inches at Tolley, 5.2 inches five miles west of Mohall, 4 inches in southeast Minot, 2.8 inches at Lake Metigoshe State Park and six miles north of Towner. Other gauge readings were significantly higher, ranging from 7 to 10 inches in the Tolley area.
“Reports of nine inches of rain were fairly common in that area,” said Tom Pabian, Upper Souris National Wildlife Refuge manager. “Fortunately is was localized.”
The Tolley area drains into the Souris River where the record downpour led to Lake Darling rising by the minute. A one foot rise in nine hours resulted in the opening of release gates at that reservoir on Sunday to 1,000 cubic feet per second. Despite the increase Lake Darling continued to rise from its 1,597 level prior to the storm to 1,598.48 feet Monday morning.
Inflow to the reservoir as a result of the deluge was estimated at 5,000 cfs, leading to the decision to increase outflows to 1,500 cfs early Monday. Releases will be ramped up until reaching 2,500 cfs on Wednesday. Other than the historic flood year of 2011, such large releases in the summer are a rarity at Lake Darling.
“The water came from everywhere. All the local drainages were flowing extremely heavy. The high water marks are simply amazing,” said Pabian. “Now we’re just trying to minimize downstream impact as best we can.”
By Monday morning the Souris River at Baker’s Bridge was nearly a foot over what the NWS considers “minor” flood stage of 10 feet. The U.S. Geological Survey dispatched teams to confirm flow rates in the Souris. By Monday afternoon the Souris at Foxholm had reached nearly 11 feet where minor flood stage is considered nine feet. A crest of 13.6 feet is expected by Wednesday and will continue at that level for several days.
The rise is significant. The NWS lists “moderate” flood stage at that location as 13 feet. At slightly over 14 feet the valley below Baker’s Bridge becomes flooded with water. At 15 feet water begins to flow over paved County Road 8.
While the brunt of the rain finally quit in the Minot area late Saturday, the system stalled along the northern tier of the state where the rainfall refused to leave. A spokesman at Lake Metigoshe State Park said the rain finally quit about sundown Sunday. However, rain returned to the region Monday. A rain gauge check at 2 p.m. Monday revealed 4.97 inches had fallen at the State Park since Saturday morning and it was still raining.
The official rainfall total at the Minot Airport for Saturday’s storm was 2.96 inches. It set a new record for the date, easily surpassing the 2.35 inches that fell in 2005. Notably, only three other times in history had more rain fallen on a single day in June. Total precipitation for the year at the airport reached 8.97 inches Monday morning. While that was only slightly more than the yearly accumulation for the date, the 5.16 inches recorded in June was well over the monthly norm of 3.47 inches.
At the North Central Research and Extension Center south of Minot the rainfall numbers were even greater with a measurement of 3.3 inches of rain by 8 a.m. Sunday. The monthly rainfall total at that location was 7.10 inches prior to additional rainfall occurring Monday.
As incredible as the rainfall totals from Saturday’s deluge are, the numbers could have been much worse. Tony Merriman, NWS meteorologist in Bismarck, said the “bullseye” of the stagnant storm actually missed most of the Souris River drainage.
“That bullseye did not fall on the Souris River Basin but the Souris did get a lot of rain, two to five inches on average,” said Merriman, noting that southeastern Saskatchewan was even harder hit than most of North Dakota. “Basically it was a cutoff low that set up over Lake Manitoba and kept rotating and lingering all weekend. It’s definitely not typical for summer months. The moisture in the atmosphere was 200 percent of normal and it doesn’t take much for a low to squeeze out that moisture.”
Merriman explained that Sunday’s wind and Monday’s combination of wind and rain was a direct spin off the cutoff low. He also had some good news for soggy river watchers as the Fourth of July holiday approaches.
“Looking ahead, we should be drying out for the most part,” said Merriman. “There’s no major rain events, not that we can see anyway, for the next seven to 10 days.”
Several days without rain is precisely what is needed while officials on both sides of the border take steps to reduce reservoir levels. Another round of heavy rain would severely complicate preventive measures already under way.
The NWS projects Lake Darling will crest at about 1,598.7 feet today. Spill level there is 1,601.8 feet and normal summer operating level 1,597 feet. According to a release issued by the Upper Souris NWR Monday, it will be mid-July before Lake Darling drops to 1,597 feet and that is with a release rate of 2,500 cfs from Wednesday until reductions begin July 8.
Releases from Alameda Reservoir in Saskatchewan will be increased to 1,750 cfs Wednesday and will continue until that reservoir returns to its summer operating level. Alameda stood at 1,844.4 feet early Monday and continued to rise due to heavy rain that fell over the Moose Mountain Creek drainage that flows into Alameda.
“Alameda is expected to gain upwards of eight feet,” stated Pabian.
Much larger Rafferty Reservoir near Estevan, and the Souris River Basin above it, escaped most of the recent storm. Rafferty has risen only slightly and little change is expected. No significant releases are planned from Rafferty which had been holding below its preferred summer operating level.
The Souris showed a dramatic rise at several points during and after the storm. The level at Sherwood jumped six feet in a matter of hours. The Des Lacs River was not spared, also rising about six feet in short order and reaching a flow of nearly 1,000 cfs before beginning to show signs of receding late Monday.
By mid-afternoon Monday the Souris at the Boy Scout Bridge west of Minot had risen nearly six feet and was flowing at 1,860 cfs. As releases from Lake Darling Dam increase so too will the amount of water at the Boy Scout Bridge. The NWS predicts a crest of 14.3 feet at that location. Flood stage there is 13 feet but no significant problems are anticipated.
According to the City of Minot, the Souris at Minot’s Broadway Bridge is expected to crest at 1,544.7 feet on Wednesday. Flood stage there is 1,549 feet. Downstream from Minot the communities of Logan and Velva are expected to see the Souris inch above flood stage in the coming days but the river is not expected to cause any major problems.