Water from Little Arkansas helping to extend life of Cheney Reservoir

Equus Beds Aquifer Storage and Recovery (ASR) Project near Bentley. (Aug. 17, 2012)
Equus Beds Aquifer Storage and Recovery (ASR) Project near Bentley. (Aug. 17, 2012) File photo

The Little Arkansas River has been able to give Cheney Reservoir a little relief during these uncertain drought-lingering days.

While the biggest boost to helping Cheney survive has come from the recent decision to shift more of the burden to the Equus Beds aquifer – Wichita’s other main water source – the Little Ark has pitched in with 79 million gallons since mid-April.

“It’s helping extend the life of Cheney,” said Mike Jacobs, the city’s water resources engineer.

That’s because enough winter snow and spring rains raised the Little Ark’s level to the point that Wichita’s Aquifer Storage Recovery program could begin its long-awaited second phase of operation on April 11.

Since that date, 79 million gallons over 23 days have been pulled out of the river. It averaged providing 600,000 gallons a day in May.

That pales in comparison to the 48 million gallons a day that Cheney and the Equus Beds have combined to average lately in meeting the city’s water needs.

But at a time when city officials thought Cheney could go dry in 2015, every little bit helps.

After the lake’s conservation pool – where the city draws its water – dropped to 58 percent of its capacity in February, recent storms had increased the pool to 73 percent as of late Friday afternoon.

Earlier this week, the City Council voted to allow the city to switch from taking 60 percent of its water from Cheney to 40 percent. The Equus Beds goes from 40 percent to 60 percent.

The switch has been made gradually so as not to disrupt the system too much, Jacobs said. Cheney was expected to be providing 40 percent by Saturday, he added.

With that change, if the drought doesn’t end, Cheney’s ability to provide water should extend to 2017 or 2018. If the drought does end, the changes mean the lake won’t run out of water for the foreseeable future, although its buffer to keep going in case of another drought would be diminished, said Alan King, director of public works and utilities.

Either way, Cheney still needs protection. That’s where the Little Ark and the ASR are helping.

The $244 million ASR is intended to provide drinking water from the Equus Beds – which is south-central Kansas’ primary fresh water source – for 550,000 people through at least 2050.

The city has water rights to draw water out of the Little Ark when it is above a certain level.

The original concept was to take that water, run it through the ASR’s treatment plant north of Wichita and store it in the aquifer for use during a future drought, Jacobs said.

After the ASR went through its first phase – more of a pilot program that had only a 11/2 million-gallon treatment capacity that ended in late 2011 – plans called for the second phase to begin in April 2012. But a drought was already well under way and there never was enough water in the Little Ark until this spring.

April saw six days where a total of 10 million gallons of water was pulled out of the river.

“We weren’t very efficient at first,” Jacobs said.

The river was high enough in early May that 19 million gallons were taken out over nine days. For eight days starting with the big storm on May 30 through Thursday, 50 million gallons of water were pulled from the Little Ark, Jacobs said.

City crews used some creative methods to alter the plans, taking the water to the ASR’s treatment plant and then to Wichita’s plant instead of recharging the Equus Beds.

“Putting it in the bank account doesn’t help us in the drought,” Jacobs said. “We’re trying to be innovative. Everything we get helps Cheney.”

The river’s stream flow was slowing down by late this week, so the city may have to stop taking water from the Little Ark this weekend.

“We’re going to get everything we can from the river when we can,” Jacobs said.

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