Courier Staff Writer
Recent heavy rainfall and warmer temperatures have some communities eyeing their rivers, anxious that a flood is on the horizon.
Thankfully, Ottumwa is nowhere near flood stage. As of Thursday, the Des Moines River level was 4.28 feet, far below the flood stage of 11 feet.
“As a matter of fact, the river has gone down some here since the weekend,” said Ottumwa Water Works and Hydro general manager Mike Heffernan.
Brad Sillbach, meteorologist with the National Weather Service in Des Moines, said due to eastern Iowa’s higher rain levels, eastern Iowa has seen more flooding and higher river levels than the rest of the state, where heavy snowfall has been the main concern.
“Eastern Iowa has seen a higher moisture content,” Sillbach said. “The snow is melting, but there’s more moisture in rain than there is in snow.”
The last time Ottumwa began to worry about rising waters was in 2010, when the city experienced some minor flooding.
“But that was mainly with stormwater back-up because the river was high and stormwaters couldn’t discharge into the river without being pumped,” he said. “We haven’t had anything real serious since 2010.”
Most of the snow between Ottumwa and Lake Red Rock is gone, Heffernan said, so even if it continues to rain, there would just be a temporary surge in the river level, though nothing approaching flood stage.
“Eastern Iowa has had some problems, but primarily from a lot of snow melt and rain all at the same time coming from northern Illinois and northern Iowa,” Heffernan said. “But we haven’t had near the snow here. Plus Illinois and eastern Iowa get more moisture than we had. Their rivers were not anywhere near as low as ours have been running.”
Sillbach said most precipitation in the forecast now will run off into the rivers as opposed to soaking into the ground.
“We’re starting to see warmer temperatures,” he said. “Rivers with ice are starting to break up, they’re getting ice pans and snowstorms will start turning into rain and the ground will start thawing. As the ground thaws, we’ll get more soaking.”
Heffernan said he couldn’t remember — at least in recent history — a time when the Des Moines River was as low as it was this winter. According to the U.S. Army Corps of Engineers at Lake Red Rock, the Des Moines River’s lowest point this winter was 0.07 feet on Jan. 24 at Ottumwa’s gauging station, though that may not be entirely accurate because when the river is that low, at times the gauges do not accurately read the river level, said Perry Thostenson with the USACE.
“Lake Red Rock has been releasing 300 cubic feet per second,” Heffernan said. “At that level, in a river as wide as ours, it looks pretty paltry.”
A continuing drought this summer is cause for concern.
“Even though we got a surge in the water now, Saylorville [Lake] is still pretty low,” he said.
When river levels begin to drop, so does the water quality.
“The water quality deteriorates, and it’s harder for us to treat,” Heffernan said.
The Dr Pepper/Snapple bottling operation near the Ottumwa Airport uses reverse osmosis units, so the harder the water, the harder it is for Water Works to treat.
“It makes it difficult for people with those units to keep on top of them,” Heffernan said. “But I’ve noticed that since we got rain, the water has come up and even though it looks pretty dirty, it’s softer water, so the water quality has improved that quickly just from the rain we had.”
As long as Lake Red Rock has sufficient water, Ottumwa will get enough to provide services to its businesses and residents.
Flood warnings throughout eastern Iowa:
As of noon Thursday, the National Weather Service had issued flood warnings for the following areas:
• Moderate flooding for the North Skunk River near Sigourney until this morning.
• Minor flooding expected along the Mississippi River in Des Moines County north of and at Burlington until Saturday morning.
• Minor flooding along the Iowa River at Wapello until Monday.
• Moderate flooding on the Iowa River at Marengo until Saturday morning.
• Minor flooding along the Cedar River near Conesville until Sunday.
• Minor flooding along the Iowa River at Columbus Junction until Sunday.
• Major flooding on the Wapsipinicon River near De Witt until Wednesday evening.
— Information courtesy of the Iowa Department of Natural Resources