News Column

Ongoing Drought Taking Iowa's Rivers Even Lower

Aug. 24, 2012

Dennis Magee

August isn't delivering enough precipitation to maintain, let alone improve, ruinous drought conditions taxing Iowa's rivers and damaging crops.

And recovery will be a long-term project, according to Mark Svoboda, a climatologist working with the U.S. Drought Monitor at the University of Nebraska.

"We've reached the apex of our precipitation for the midsection of the country -- it's pretty much downhill from here until next spring -- so rapid, large-scale improvements would be unexpected, although certainly not impossible," he added in a weekly update released Thursday.

Despite recent rains -- some areas got significant amounts -- no area of the Iowa improved its classification, according to the U.S. Drought Monitor. In fact, some counties moved from D2, or severe, drought conditions into D3, extreme, drought conditions.

In north-central Iowa, those include Hancock and Cerro Gordo counties and southern portions of Floyd, Winnebago and Worth counties.

Jon Nania, a hydrologist with the U.S. Geological Survey based in Iowa City, is charged with monitoring the state's rivers and streams. He also sees little evidence the drought has lost any of its potency.

"It's not lessening. It's not doing that, that's for sure," he said.

The cause for drought conditions is not difficult to determine. Rainfalls totals for much of the year and across most of the state have been well below normal.

According to the National Weather Service, Waterloo hasn't seen average precipitation since April. Since then, official totals show Waterloo is 9.91 inches below average, 4.15 inches short in July alone. That month a mere .76 inches fell, according to the weather service.

The Cedar River is flowing below levels recorded in July -- which were already approaching historically low rates -- and far below levels recorded in August 2011.

On Aug. 17, the Cedar in Waterloo was discharging 573 cubic feet of water per second, according to the U.S. Geological Survey. The river this morning was discharging 439. The drop represents a decline of more than 23 percent in seven days.

To illustrate the situation on the state's waterways, consider this: By the time the Iowa River nears the Mississippi River, it has collected water from dozens of tributaries, including the Cedar. This morning, the Iowa was discharging 1,100 cubic feet per second -- only about 60 percent of what flowing in the Cedar alone last August in Waterloo.

The Wapsipinicon River in Independence is faring slightly better at the moment. The river this morning was discharging 40 cubic feet per second. A week ago, the Wapsie was at 45.

The Iowa Department of Natural Resources reports similar affects on the state's lakes. Some lakes are dropping an inch every four to seven days, according to the agency.

When rain does fall, Nania and his colleagues note the state's rivers are behaving differently.

"The rivers do come up a little bit. But what we see this year is when the rivers comes up, they come back down really quickly," he said.

He likens the affect to urban waterways, which flash higher because of runoff from paved surfaces. Such a reaction, though, is atypical for Iowa's major rivers, like the Cedar and Wapsipinicon, according to Nania.

Because of low flow, the U.S. Geological Survey is doing special measurements for the U.S. Army Corps of Engineers, which manages four major reservoirs in Iowa. The closest is Coralville Lake on the Iowa River.

"They want to make sure they can release the minimum amount that they are allowed to and not a drop more," Nania said.

His agency monitors 180 points on Iowa's many rivers and streams. Because of low levels, though, Nania and his colleagues had to move sensors at about 60 sites. Among them were sensors on the Turkey River at Spillville and on the Wapsipinicon at Oxford Mills.

"Otherwise we would be monitoring air or sand or something," he said.

In his 17 years, Nania said he cannot recall repositioning so many sensors.

"Not to this extent. Not this widespread at the same time," he said.



Source: (c)2012 Waterloo-Cedar Falls Courier (Waterloo, Iowa). Distributed by MCT Information Services


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