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Drought persists, river shows it

July 28, 2012
By GARRY BRANDENBURG , Times-Republican

HOW LOW can the river go? Rivers in Iowa seldom go completely dry- Very low, yes. Right now the river gauging station on Highway 14 is reading 9.25 feet. This a relative and arbitrary number only as a benchmark to compare flow rates over time. It does not mean the river is that deep. River channels always have high spots and low spots. Deeper holes are where past currents have cut into a bank or behind a blockage of trees. The present flow rate is a tiny 62 cubic feet per second.

HOW HIGH can the river go? On June 13, 2008, the river gauge reading was 21.79 feet with flow rates of 22,388 cubic feet per second. This is the all-time record of modern times. Access into and out of Marshalltown was limited or closed due to flooded highways. It was a mess as flood waters covered a great share of the floodplain lands within the valley. The same story happened on many other rivers in Iowa. What we experienced was not an isolated incident.

HAS THE RIVER ever been higher? Yes, during the most recent geologic event when melting of the Des Moines lobe of the Wisconsinan glacier was taking place. This time frame started about 16,000 years ago when a global warming trend was setting in. It took about 5,000 years for the glacier's leading edge to melt back to the area we now call the Iowa/Minnesota border. And during that time frame of 5,000 years, the retreat (melting) was not a steady process. There were periodic restarts or advances of the glacier leaving subtle moraines on the landscape. But in the long run, Earth's natural warming cycle was playing out. All the water from this huge segment of ice called the Des Moines lobe had to go somewhere. Summer flows of torrents of water off the glacier front and margins cut and created broad floodplains that flowed with water filling the entire valley. There were no gauging stations to record how high the water was. But the message of those past events is written in the way our landforms exist today.

Article Photos

T-R PHOTO BY GARRY BRANDENBURG
How low can it go? Well, that depends. For sure this year’s drought conditions are reflected in low water flow within the river channel. Geologists call it ‘base flow,’ meaning the only water entering the river is from the super slow seep of water out of the sub soils of all adjacent land. As today’s photo shows, walking across the Iowa River at Timmons Grove is easy. Floating with a canoe or kayak is actually hard work. What comes around goes around and in a few years, flooding will be the headline of the day. If we do not like Iowa weather, just wait five minutes and it will change.

The Des Moines River valley took most of the ice melt while the Raccoon River to the west was being carved into the landscape along that ice margin. Our Iowa River resulted from numerous outflow systems from the eastern margins of the ice. Just in Marshall County, Linn Creek, Honey Creek and Minerva Creek were major contributors of water to the Iowa. Contained within its water was a messy mixture of silts, sands, gravels and other formerly ice-embedded debris, all to be sorted and deposited along the way.

We live in a region of the world and in a climate that does not lend itself to serious extremes of dryness or wetness. One may want to argue that we do get extremes of weather. Okay, I'll agree. But compared to what Earth can produce in other locations, we haven't seen anything yet. Our extremes of weather are quite mild compared to the deserts on one hand and rain forests on the other. It is something we have to adapt to as best we can. And we can.

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RAGBRAI bike riders made headlines this week as they peddled their way across Iowa. Here is an interesting bit of information. If one takes only the uphill elevation gains and adds them up, those adventurous bikers climbed the equivalent of a mountain 15,770 feet tall. Since Iowa does not have mountains that big, we just break it down into many 'little' hills that must be faced head on, sometimes against the wind and the heat just to make it interesting. Of course each hill going up, luckily, has a downhill slope for easier travel. By the time RAGBRAI bike tires dip into the Mississippi River water, they will have gone downhill a lot more than 15,770 feet.

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FISH KILLS from low water levels and with oxygen saturation levels going below three parts per million, fish are dying in small ponds across the entire Midwest. There is not much a person can do about it. Starting over with new stocking of fish next year is likely the best bet ... if we get good fall rains, winter snow and a normal spring.

Trout stocking in northeast Iowa streams has been halted in several places because the waters have become too warm for trout. DNR Hatchery folks cannot risk taking fish out of 50 degree water and putting them into streams with 80 degree temps. When rains returns, trout stocking may resume. Locally, those species of fish without deep water refuges that are susceptible to low oxygenated water are northern pike, yellow perch and walleye. Channel catfish and bullheads are more tolerant of warm water but even they have limits.

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NEW PLAYGROUND equipment has been installed at Timmons Grove County Park near the campground site. This is just one part of long-term park upgrades that are envisioned by the staff and board members of the Marshall County Conservation Board. The work crew picked the hottest, driest times to accomplish the tasks of digging the holes, assembling the play elements and getting everything level and plume before concrete bases were filled. Now with its thick tree mulch base in place, it is ready for kids to climb on and enjoy. Go for it.

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A DEER with chronic wasting disease was confirmed in southern Iowa at a private game farm. With confirmed cases in all the surrounding states, it was just a matter of time before it was going to appear. However, the trading and selling of deer from private game farms is highly suspect as the conduit by which the disease got here. One may never know for sure. In the meantime, DNR officials will be extra vigilant in testing deer from fall hunts of wild, free-ranging deer. Since 2002, Iowa DNR staff has tested more than 42,557 deer for CWD. They included more than 4,000 additional deer from privately owned deer and elk herds. Those surveillance efforts to date have turned up zero cases of CWD. Now that the Davis County, Iowa case has been confirmed, it is under quarantine by the DNR and the Iowa Dept. of Ag and Land Stewardship.

CWD is a neurological disease that only affects cervids such as deer, elk and moose. An abnormal protein, called a prion, affects the infected animal. They loose weight, display abnormal behavior and lose bodily functions. Signs include excessive salivation, thirst and urination, loss of appetite, listlessness and drooping ears and head. Prions can attach to soil particles and spread the disease to other deer many years later. This is a tough situation for wildlife officials. Stay tuned.

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Garry Brandenburg is a graduate of Iowa State University with BS degree in Fish & Wildlife Biology. He is the retired director of the Marshall County Conservation Board. Contact him at PO Box 96, Albion, IA 50005.

 
 

 

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