Rain, rivers, reservoirs
It’s far too early to determine how much water will flow through the Souris River next spring, but there are some ominous signs deserving of close attention in the coming months.
The amount of moisture that has accumulated this year, particularly from late rains as freeze-up looms just weeks away, is the most in recorded history at some reporting points in the region.
The amount of soil moisture alone, including potholes, should not be considered a sole source of potential high runoff next spring. However, it is viewed by forecasters as one of several elements that can have a major influence on how much runoff enters a particular drainage.
Daily rainfall records were snapped and Bismarck, Dickinson, Jamestown, Grand Forks and Fargo this past Monday. In saturated ground throughout the western part of the state, the bustling truck traffic of the Bakken oil field was halted to allow soggy roads time to dry out.
Minot’s rainfall total for the year at the North Central Research and Extension Center south of the city has reached an astounding 31.32 inches, the highest ever recorded by 4.33 inches and there are still two and one-half months remaining in 2013. At the Minot International Airport on the city’s north side the rainfall total for the year has reached 24.26 inches, the fifth-highest in 96 years of collecting weather data.
Similar numbers have been recorded all directions from Minot. Fields are wet. Potholes are full to overflowing. Evaporation is minimal due to the onset of cooler temperatures as winter approaches.
“I’ve looked at satellite imagery. A lot of wetlands are pretty high right now,” said Allen Schlag, National Weather Service hydrologist in Bismarck. “Geologically speaking we’ve seen wetter, but it may have been 8,000 years ago. I don’t have a real answer on that.”
What is known is that as recently as 12,000 years ago the lower basin of the Souris River was actually glacial Lake Souris. While no one is suggesting a return of Lake Souris, it does help put today’s wet landscape in perspective.
“We have long-term cycles in the climate around here,” explained Schlag. “It can be exceptionally wet, then dry, or vice versa. It is not unusual. How frequently we’ve had such levels of high water, I can’t really say.”
There are indicators virtually every direction from Minot that point to the rarity of the wet conditions that the region has encountered and continues to encounter. Numerous roadways have been built up, some of them several times, to avoid rising water from potholes that were never previously a problem. Many roadways are under water, too.
Another indicator of the current wet cycle is the loss of cottonwood trees throughout several drainages in the state. In the Minot area cottonwoods sprang up along the perimeter of wetlands and grew to great heights as the wetlands continued to cycle, holding water one year and drying up the next. Today many of the cottonwoods have been consumed by the same wetlands that gave them life.
“Some of them are 80 to 120 years old and they’ve died well out into the wetland,” said Schlag. “Just in the past five to 10 years we’ve killed them with high water. We’ve seen a tremendous loss of wetland shoreline cottonwoods that have been with us for a long time.”
The cottonwoods marked the high water line for countless sloughs and potholes that are now much larger and deeper than they have been for the life of the trees or longer.
“Clearly we are seeing more water on the countryside that isn’t historically normal,” said Schlag.
Historically, sloughs and potholes have filled during spring runoff or during spring rains. Now many of them are full heading into the winter season, meaning they may have little influence on capturing excess runoff next spring, should such runoff occur.
Regional rivers have not been immune to this year’s excessive precipitation either. Following rainfall earlier this week flows jumped to record levels for the date at several locations. The gauge on the Wintering River near Karlsruhe reached 46 cubic feet per second Tuesday. That compares to an average of 5.3 cfs and broke the record of 26 cfs set in 1995.
The scenario was repeated elsewhere as rain falling on saturated soil quickly made its way to drainages. Long Creek at Noonan reached 36 cfs Tuesday. Average for the date there is 1.2 cfs. The previous record of 20 cfs was set in 1979. Deep River Creek at Upham reached 15 cfs Tuesday where the average for the date is 1.2. Willow Creek near Willow City was flowing at 52 cfs Tuesday. The average for the date is 8.3.
Reservoirs on the Souris are high. However, their levels can be adjusted by releases through water control gates.
“We’re releasing 300 cfs now and may increase that a little bit,” said Frank Durbian, Souris River Basin Complex manager when asked about water levels in Lake Darling and the Souris River. “We were prepared to release more but the upper river basin in Canada did not receive as much rain as we thought possible.”
The level of Lake Darling was 1,596.58 feet Tuesday afternoon. By international agreement the lake must be reduced to 1,596 feet by Feb. 1 of each year. According to Durbian, the operating plan is to release water from Lake Darling through the winter.
“It will be flowing for quite a while,” said Durbian.
The amount of flow released from Lake Darling will be dependent upon the amount of water entering the reservoir and an assessment of conditions downstream.
Two large reservoirs in Saskatchewan, Rafferty Reservoir near Estevan and Alameda Reservoir near Oxbow, must also draw down prior to Feb. 1 as stipulated in the basin’s international agreement. As of Tuesday, Rafferty was 4.5 feet above the Feb. 1 target level and Alameda 2.7 feet higher. Those levels are not generally considered excessively high for this time of year.
As for the Souris River, it is running higher than the historic norm for mid-October. Tuesday’s flow at Baker Bridge was recorded at 317 cfs. The flow was approaching 500 cfs late Tuesday at the Boy Scout Bridge west of the city. At the border crossing near Sherwood, the Souris was flowing at 88 cfs Tuesday. Average for the date is 4.4. The maximum flow for the date at Sherwood is 276 cfs set n 1994.
A U.S. Geological Survey website of river gauges on the Souris was unavailable Tuesday due to the Federal government shutdown, meaning no readings were available from rapid deployment gauges at Tolley, Burlington and Minot’s Broadway Bridge.