October 2007

The DNR communications team works with agency experts to develop the weekly questions and provide the answers. This feature addresses current DNR issues, interesting topics, or the most frequently asked questions from around Minnesota.



It's been about two months since the devastating floods in southeastern Minnesota. Now that DNR fisheries experts have regrouped and evaluated conditions, what's needed to return the Whitewater River and it's tributaries to quality trout fishing conditions?

I have been asked this question many times since the flood and I think the answer is very simple, "water quality." Floods and the resulting changes in stream appearance don't make or break the stream. If the watershed was in good shape before the flood then the streams will recover quickly.

Although rocks and pools got moved around, the fish will be back. In a sense, the streams merely threw back at us the silt we have smothered them in, and in places now resemble mountain streams. How long will it take before the silt smothers them again? That is the real question here. With the changes and trends in cropping practices in the southeast the future doesn't look good. We have passed the peak of water quality and are now looking at the result of a region that has changed from dairy farming and the associated rotation of oats, alfalfa, pasture and corn, to corn/soybean row cropping. The flood has little to do with it but it will make a good excuse for those that don't want to acknowledge the slower less dramatic destruction that is happening on the landscape day to day.

- John Huber, hatchery supervisor, DNR Crystal Springs Hatchery


The past few winters have been relatively quiet across much of central and southern Minnesota. Is there anything in Minnesota's historical weather records that indicates what type of winter we will have this year?

In any Minnesota winter there will be spells of bitterly cold weather, bouts of snowfall... sometimes heavy, and at least one January thaw. Most communities in southern Minnesota average around 30 days during the winter where the minimum temperature drops below zero. Northern Minnesota locals average 50 to 65 days of below-zero weather. The National Weather Service's Climate Prediction Center studies sea surface temperatures in the equatorial Pacific for outlooks. Water surface temperatures over the Pacific Ocean at the equator are currently cooler than their historical averages. Cooler than average sea-surface temperatures in this area of the Pacific create the phenomenon known as La Nina. A La Nina condition would favor a better chance for above normal snowfalls over northern Minnesota from December to February with a slightly better chance of below normal temperatures in the north as well. This La Nina-influenced signature lessens in central and southern Minnesota where it is closer to a coin toss for above or below normal temperatures and precipitation.

There is also the persistence factor. Recent winters have simply been quite warm for the past ten years, with one lone exception: The winter of 2000-01. It's this repeating behavior of mild winters that is part of the mix that goes into the outlooks. The Climate Prediction Center gave persistence the edge in its outlook for the winter of 2007-08 and put much of the central United States including Minnesota in the area with a tendency for above normal temperatures and equal chances for precipitation. http://www.cpc.ncep.noaa.gov/products/predictions/long_range/.
The last three La Nina winters for Minnesota were: 1998-99, 1999-2000, and 2000-01.

- Peter Boulay, DNR climatologist