Tuttle Creek Lake’s water holding capacity sliced in half from sedimentation
TOPEKA — Tentacles of the irrigation-based agriculture economy of Kansas extend far from fields of lush, tall corn to the ethanol producers, dairy and beef facilities, meatpacking plants and finally the homes of people living in the state’s rural areas.
Earl Lewis, chief engineer of water resources with the Kansas Department of Agriculture, told state legislators Monday this chain could be broken in some areas of the state as consumption of groundwater from the Ogallala Aquifer continued to outstrip natural replenishment.
“We’ve got a multibillion-dollar industry built on that economy,” said Lewis, pointing to maps showing swaths of western Kansas counties fed by the Ogallala wouldn’t sustain another generation of hefty irrigation. “That’s really where we see a significant change in the economy.”
He told House and Senate members on a special water committee that Kansas farmers annually planted 25 million acres of crops. Two-thirds of 3 million irrigated acres in Kansas rely on water from the Ogallala. To put irrigation into perspective, 87% of water consumed in Kansas each year goes to irrigation of corn, soybeans, wheat and other crops that wouldn’t be nearly as productive if rain was the exclusive source of moisture.
Warning signs about overreliance on aquifer irrigation have been visible for decades in Kansas, but no solution has been found due to conflict among landowners seeking to preserve water rights and the environmentalists and others pushing for expansion of water conservation programs.
“That’s really where our threat lies,” Lewis said. “At the end of the day, this isn’t about whether we think somebody is being bad or being inefficient. It’s about how to we want to make sure we have a resource that supports our economy in that area for the long term. What’s the conscious decision we want to make now about our future for that part of the state?”
He said state had demonstrated the value of flexible accounts allowing a producer to draw extra water from the aquifer in one year as long as the producer moderate usage to stay under a cap over a five-year period. In the ongoing drought, farmers have again turned to flex accounts to pump water necessary to save crops.
Connie Owen, director of the Kansas Water Office, briefed legislators on challenges to sustaining reservoirs suffering from sedimentation. The state’s network of reservoirs, including Tuttle Creek Lake near Manhattan or Clinton Lake at Lawrence, exist as a major source of drinking water.
Siltation at Tuttle Creek had reduced the reservoir’s capacity to 52.8% by 2021, which meant the lake was almost half full of soil runoff.
“That’s the most critical right now. That reservior is the workhorse of northeast Kansas,” Owen said. “This is not a mistake. It is not a surprise. This is just the way reservoirs work, but over time it becomes a problem. We have to figure out what are we going to do with that shrinking capacity.”
She said the latest projection indicated Tuttle Creek would fall to 10.1% in terms of water capacity, meaning it was 89.9% full of sediment, by 2070 without intervention.
“Your sedimentation maps — a little frightening,” said Rep. Ron Highland, a Wamego Republican who attempted to push through a major water management bill in this year’s legislative session that included additional state government oversight and higher water fees.
Owen said the state spent millions of dollars dredging the heavily silted John Redmond Reservoir, which is relied upon to help cool the Wolf Creek nuclear power plant.
She said discussions were continuing with the U.S. Corps of Engineers about an alternative strategy for Tuttle Creek Lake. Instead of traditional dredging that removed sediment for relocation, the idea would be to rely on water injection dredging. The technique has been successfully used in harbors and waterways, she said, but not in a reservoir setting. The Legislature appropriated funding for a pilot project at Tuttle Creek.
“It is a barge that travels across the water, injects water under pressure to the bottom (and) resuspends the sediment so that it can more easily flow out,” she said. “We want to make sure there won’t be negative impacts downstream to wildlife habitat or to public water intakes.”
She told lawmakers she had concerns about water quality due to nutrient runoff from fields into lakes and rivers that spawned algae blooms. Toxic blooms create substantial costs to communities that must build treatment plants to address nitrate contamination of water for human consumption, she said.
“It is nonpoint-source pollution so there are no regulations about how much you can use and where you can use it,” Owen said. “It is of concern. We don’t want to jeopardize our agricultural economy, but we also want to protect our water quality.”
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