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Hidden Treasure: Managing Iowa’s Groundwater

Posted on July 25th, 2016

Hidden Treasure Clear Crek 42012 was declared the hottest year on record, it came as no surprise to Iowans. Spring had started ahead of schedule, causing trees to bloom in March. By July, the state was drying up. With virtually no rain and record high temperatures (107 degrees on July 23 at three locations), Iowans were in the midst of the worst drought since 1936.

In Northwest Iowa near the city of Rock Valley, the drought created anxious moments for livestock producers. The

region is home to many large-scale animal feeding operations. Managers feared that soon they wouldn’t have enough well water for their animals. The potential for catastrophic livestock deaths was clear.

 

Who You Gonna Call?

In the midst of that hot, dry summer, Rock Valley Rural Water contacted the Iowa Geological Survey’s Mike Gannon and Jason Vogelgesang for help. “The severity of the situation required an emergency response,” Gannon says. Today, Gannon, Vogelgesang, and Antonio Arenas Amado make up IIHR’s new Water Resources Management (WRM) team. Many Iowa cities, industries, and livestock producers are turning to Gannon and his team for expertise on modeling and management of water resources.

At Rock Valley, they were able to implement a short-term solution by pumping water about a mile from the Big Sioux River to a nearby abandoned gravel quarry, which served as a groundwater recharge basin for water storage. Groundwater levels rose immediately. The project was so successful, it turned into a more permanent solution involving a nearby intermittent stream.

 

A Vital Resource

Although Iowa has excellent groundwater resources, demands from growing urban areas, ethanol production, large-scale livestock feeding operations, and industry have intensified. In some parts of Iowa, groundwater is being pumped out of the aquifer faster than it can recharge. “You can’t keep increasing aquifer withdrawals forever,” Gannon says.

In addition, new state regulations to protect and sustain the Jordan aquifer limit how much groundwater can be extracted. As a result, many cities and industries are looking for new sources of water.

Hidden Treasure_Clear Creek 1The WRM team conducts predictive local-scale groundwater modeling, which can be used for drought assessments,

aquifer storage assessments and recovery, water sustainability studies, and water-quality assessments. IGS researchers have developed groundwater flow models for four of Iowa’s bedrock aquifers. The models are good predictive tools that can be used to look at various pumping rates, future well locations, the effects of climate

fluctuations on water resources, and future water-quality impacts. They can also function at the local scale. “You can start to zoom in and see how people are affected,” Vogelgesang says.

The WRM team can help Iowans cope with the intensifying flood-to-drought cycle by enhancing groundwater storage. “What we try to do is capture and store as much water (both surface water and groundwater) as we can during the flood cycle so it can be used during the drought cycle,” Gannon says. They achieve this through a combination of strategies, including recharge basins, constructed wetlands, and low-head dams on rivers and streams. Water captured behind these structures provides both surface water and groundwater storage.

For Rock Valley, they diverted an intermittent stream to the former quarry/recharge basin, holding water in place

to increase infiltration. “Water levels in some of these wells rose about 17 feet,” Vogelgesang says. Even when the creek stops flowing during a drought, water storage in the basin and surrounding groundwater allows the rural water system to continue providing water to customers.

 

A Thirsty World

Elsewhere, these issues often affect municipal drinking water supplies. “Drinking water issues affect the economy

tremendously,” Vogelgesang says. And as communities grow, water managers realize they can’t continue to increase pumping rates from their deep Jordan aquifer wells. They need secondary water sources, such as a shallow bedrock aquifer or the sand and gravel aquifers adjacent to major rivers and streams. Vogelgesang uses geophysical tools such as electrical resistivity to develop a 3D image of what’s beneath the ground to find the best potential shallow

water sources. This data can also feed into the local-scale groundwater models to make them better predictive tools.

The WRM team is also studying the ways these strategies can affect water quality, impact wildlife and sedimentation, and potentially cause nitrate levels to increase.

Assistant Research Scientist Antonio Arenas Amado is focusing on these water-quality issues. He recently worked with the city of Ottumwa, where officials were concerned about nitrates in the river that provides the city’s drinking water. The city currently collects and stores river water during low-nitrate periods for later use, and is considering investing in a nitrate removal facility. “They are at the mercy of whatever happens upstream,” Arenas explains. He looked at 30 years of historical data in the Des Moines River and analyzed the trends. He found weather patterns were becoming more extreme, along with increasing trends in the number of days with high nitrate concentrations and nitrate concentration variability.

 

Water for the Future

Should Iowans be concerned about declining aquifers? “I think it’s more of a management issue,” Gannon says.

Vogelgesang agrees. “People want answers,” he says. “They want to know what will happen in the future.”

He adds, “It’s all dependent on using good science and sound engineering so our water resources are sustained for future generations.” Fortunately, the WRM team is well-equipped and ready to provide these services.

Hidden Treasure_North Liberty Well

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