The past three falls have been so wet they've served as alert for spring in flood-prone areas. Not this year.
In much of Minnesota, the last three autumns brought vivid color and a lot of talk about spring flooding to come. This year -- not so much of either, thanks to a drought.
In addition to reducing the potential for calamitous flooding, dry conditions have also helped farmers and public agencies zip through their chore lists.
The Minnehaha Creek Watershed District has been restoring shoreline plantings in areas along Lake Minnetonka where recent high water kept them from taking root. The district also has been able to carry out some controlled burns of unwanted vegetation and dredging of silted-in retention ponds, said spokeswoman Telly Mamayek.
Construction of the new light-rail transit line between Minneapolis and St. Paul speeded up in recent weeks after rain delays in the spring, Metropolitan Council officials said.
Farmers, meanwhile, had a smooth harvest, with dry conditions reducing the need to run grain dryers.
At the same time, the drying ground across much of Minnesota has increased its capacity to absorb rain and snowmelt. That could reduce the amount of water flowing to the region's rivers and streams, which in recent springs has triggered millions of dollars' worth of sandbagging and levee-building or resulted in waterways jumping their banks.
"This gives us a little breathing room," said Greg Gust, hydrologist with the National Weather Service office in Grand Forks, N.D., along the flood-prone Red River.
At Fargo, N.D., the Red still was running at three times its median volume last week, but that was about one-fourth where it stood at this time two years ago. The river has not run at or below its historic median flow on any date since August 2006.
Rainfall in much of the Red River Valley has been slightly below normal since late July. But across southern Minnesota, it has been near all-time lows. Near Waseca, the soil is so hard that it has resisted fertilizer applications and even damaged farm equipment, said Tom Hoverstad, scientist with the University of Minnesota's Southern Research and Outreach Center. The soils in that area could hold an additional 5 inches of rainfall, Hoverstad said.
Rivers in the region are extremely low -- good for water clarity, but not so good for fish and other aquatic life, said Jason Moeckel, supervisor in the DNR's Division of Ecological and Water Resources. The Blue Earth River on Friday was running at 5 percent of its historic median flow -- "almost dry," said Steve Buan, hydrologist with the North Central River Forecast Center.
The coming winter and runup to it carry concerns for spring flooding even with the drought. A sudden heavy rain followed by a deep freeze could make soils impermeable to snowmelt, increasing runoff into streams and rivers, Buan noted. A winter with little snow would have a similar effect, allowing soil to freeze deeply, while also leaving wildlife exposed to cold and predators, said Ed Boggess, deputy director of the DNR's Fish and Wildlife Division.
"Rain, crust and little snow are not good for anything," Boggess said.
At the Minnesota Landscape Arboretum, operations director Peter Moe said the ground is cracked and workers have been continuing to water gardens and trees. Last year, fall watering wasn't on the to-do list. Meanwhile, Moe said, the drought dulled what the DNR had boasted would be the best fall color display in years.
What's needed now, he said, is a slow drop in daily temperatures to help plants reach maximum hardiness and a return to normal precipitation, since snow can insulate plants during the winter.
Weather watchers generally are describing the current drought as a short-lived, typical variation, likely to be overpowered soon by larger atmospheric forces that are setting the table for a colder- and wetter-than-normal winter. The short-term forecast for the Twin Cities calls for sunny weather through this week, but the national Climate Prediction Center is indicating strong chances of above-normal precipitation across Minnesota between now and Thanksgiving.
Even more broadly, Gust, of the Grand Forks office of the Weather Service, said the dry spell will probably be just a small break from a decades-long wet trend. The five-year running average of annual rainfall at Fargo, for example, has jumped from about 18 inches in 1991 to about 26 inches.
"Enjoy it while it lasts," he said.
Bill McAuliffe • 612-673-7646
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