Courier Staff Writer
While rainfall has returned to normal in the last two weeks, water levels are still below normal or near historic lows.
Mike Heffernan, general manager of Ottumwa Water Works and Hydro, said Lake Red Rock’s levels are continuing to drop.
It’s projected that the lake will release 320 cubic feet per second (cfs) through Oct. 15.
“That’s the minimum they like to outflow to keep enough water going to the Cargill Eddyville complex and Alliant Energy generating station, and also to help us out, too,” Heffernan said.
But once output drops below 300 cfs, Cargill and Alliant could start hurting.
“They’re projecting the lake level [Tuesday] to be 742.05 feet, and in 15 days it will drop to 741.9 feet,” Heffernan said. “That’s only 0.15 inches, but it is still dropping. I anticipate they’ll keep those outflows at 320 [cfs] since the lake level is dropping.”
He said the lake is not getting as much water as it’s releasing.
“It can’t do that forever,” Heffernan said. “I imagine if we don’t get rain in the next few months, they will drop the outflow to below 300 [cfs].”
While Cargill Eddyville and Alliant Energy would be impacted, Heffernan said Ottumwa would be fine.
“It would create hardships for the Cargill Eddyville complex, because they pull water out of the [Des Moines] River but they don’t have a dam,” he said. “Once Red Rock’s outflow drops below 300, they have to start pumping well water to replace the water they’re taking out. That makes that water, when it returns to the river, more difficult for us to treat. Well water in this area is very poor quality.”
Heffernan said the same goes for Alliant, which pulls water to keep its towers cool.
“A low river level is hard on their pumping equipment, because once again, they don’t have a dam,” Heffernan said.
But he said Ottumwa has nothing to fear for the moment.
“At a meeting three weeks ago, the state geologist, Bob Libra, was there,” Heffernan said. “He said we’re not at historical lows yet, but we don’t know where we’re at in the drought cycle. We don’t know what we’re dealing with yet.”
While well water is generally poor quality in southeast Iowa, Heffernan said most rural homes are hooked up to Wapello County Rural Water, which gets its water from Ottumwa Water Works and Hydro.
Meanwhile, the Rathbun Regional Water Association gets its water from Rathbun Lake, which has not experienced the hardships Red Rock has this summer.
“They have plenty of water there,” Heffernan said. “Rathbun Lake discharges a minimal amount — 5 to 10 cfs — so they don’t have to release as much water to feed big places like Cargill and Alliant and Ottumwa.”
Both Saylorville Lake and Lake Red Rock sit on the Des Moines River, so whatever happens there will affect Ottumwa in the long run, he said.
“We’ve been getting some rain, but it’s been soaking right into the ground, with virtually no run-off,” he said.
For more information, go to www.iowadnr.gov/watersummaryupdate.