Nebraska Ag Connection - Water Sustainability Starts with Water Stewardship

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Water Sustainability Starts with Water Stewardship
Nebraska Ag Connection - 12/14/2018

From cattle and hogs to corn and dry beans, the agricultural diversity of Nebraska is one of its unique characteristics. With a vast number of commodities produced within the state, it's no wonder that the agricultural industry pumps $25 billion into the state's economy on an annual basis. The success of Nebraska depends on the success of agriculture, which is why the Institute of Agriculture and Natural Resources (IANR) remains steadfast in its efforts to support and strengthen the industry.

Strengthening agriculture in Nebraska means examining the factors contributing to its success. With an elevation drop of 4,584 feet from west to east, the state's unique geography supports everything from grazing cattle to growing grapes for wine production. Coupled with the variety of landscapes is Nebraska's abundant natural resources, namely water.

Located on a steep east-west precipitation gradient, Nebraska agriculture benefits enormously from a vast, though finite and vulnerable supply of high-quality groundwater. The source of Nebraska's plentiful groundwater supply is the High Plains Aquifer, which includes the Ogallala Aquifer. The aquifer spans eight states and nearly 175,000 square miles. While nearly 70 percent of the volume of the aquifer is beneath Nebraska, one should not assume that water is not a concern for the state. Understanding the increasing incidence of water contamination and how to implement better water management practices are just two of the major issues facing the state when it comes to water. Limiting water woes while ensuring a sustainable supply for future uses is critical for Nebraska, which is why IANR is actively involved in a number of efforts to protect and conserve the state's most important natural resource.

High nitrate levels are a common water quality issue. While nitrate does occur naturally at low concentrations in groundwater (~2 mg/L nitrate-N), increasing concentrations in excess of 5 mg/L are linked to areas where nitrogen is over applied to lawns, gardens and crops. Additionally, nitrogen is also carried in waste found in feedlots and animal yards, and overapplication of this nitrogen source can also contribute to elevated nitrate-N concentrations in a few areas.

Dan Snow is the director of the university's Water Sciences Laboratory. Snow leads the lab in its efforts to identify new methods to evaluate water quality issues such as nitrate contamination, along with challenges concerning water quantity. He said in the majority of cases he's studied, the source of contamination is from commercial fertilizer, or more specifically, overapplication of nitrogen and irrigation water exceeding plant needs. Nebraska leads the nation in the amount of irrigated cropland. When too much water is added to a fertilized soil, much of the nitrate will wash down below the root zone and eventually percolate the water table.

"In my opinion, nitrate contamination is the biggest issue affecting groundwater in Nebraska," Snow said. "Nitrates have been increasing across the state since the 1970s."

Testing public water supplies for nitrate is required by the Environmental Protection Agency. The maximum contaminant level for public water supply is 10 milligrams per liter. In order to maintain a healthy water supply, communities across the state, such as McCook, Hastings, Grand Island and Creighton, have had to install costly treatment solutions. The costs for treating public water supplies to levels required under the Safe Drinking Water Act are increasing statewide and most of these costs are passed on to consumers.

To help communities manage the quality of their water, scientists across the university are researching areas with high nitrate contamination, as well as emerging contaminants, which have not been studied as extensively as nitrates. Tiffany Messer, an assistant professor in the Department of Biological Systems Engineering and School of Natural Resources, studies nitrate contamination and its impact on emerging contaminants in rivers and streams, two common sources of drinking water. Her research focuses on the way contaminants move through surface water and interact with groundwater. Armed with this information, Messer is working with her colleagues and other partners to take steps to improve Nebraska's water quality through best management treatment practices.

Sitting on top of the deepest and widest part of the High Plains Aquifer means that Nebraska has more groundwater than any other state overlying the aquifer, but that doesn't mean that it is immune to challenges when it comes to the amount of water available.

Water compacts with neighboring states, contamination issues and drought coupled with the amount of water being pumped from the aquifer by irrigation wells have put into question Nebraska's water quantity levels. The depletion of the High Plains Aquifer has been well publicized in recent years; however, the most severe water quantity concerns are found in neighboring states.

"Nebraska has maintained its groundwater levels. The volume of groundwater stored in Nebraska is pretty close to what it was predevelopment," said Troy Gilmore, groundwater hydrologist in the Department of Biological Systems Engineering and School of Natural Resources. "In some places we've had rising water tables due to leaking out of canals, for instance, which has offset declining groundwater levels in other areas."

Surface water systems such as streams, rivers and lakes can both gain and replenish water from groundwater sources. This is why a few areas of the state, such as southwestern Nebraska, have seen streamflows decline due to decreasing groundwater levels. Along with Gilmore, others within IANR are constantly working to develop conservation technologies, such as sensors that can detect a crop's exact need for water, and the amount of water available in the soil. The sensors allow farmers to apply only the amount of water necessary, protecting both water quality and quantity.

"To truly sustain this vital resource well into the future, we must preserve both the quality and quantity of water," Gilmore said.

Nebraska has made it a priority to manage its vital resources now, to prevent major problems in the future. Since many of these issues are customized to the state, Nebraska has developed its own customized system of management. In most states, natural resource districts are divided by county, whereas in Nebraska the districts are based on river basin boundaries.

Programming delivered by each of Nebraska's 23 Natural Resources Districts (NRD) will vary based off the needs of the local area. The university plays a major role in providing each district with the education and information it needs to manage its district and disseminate information to the public. For instance, IANR's Conservation and Survey Division (CSD) has been instrumental in helping the state's natural resources districts prepare water management plans required by law. Monitoring groundwater levels, providing computer simulation to assist water management and integrating geochemistry with studies of groundwater geology are just a few of the resources the CSD provides.

The NRD system and its support network has worked well enough to garner international interest. In 2017, Nicholas Brozovi?, director of policy at the Daugherty Water for Food Global Institute at the University of Nebraska, hosted a group from the World Bank wanting to learn about Nebraska's approach to groundwater management. The group was interested in the NRD structure, funding and decision-making processes to identify ways to replicate similar approaches in their own countries.

The abundance of water in Nebraska means it's going to take a team effort to sustain the resource into the future. Researchers at IANR have developed dynamic relationships with groups like the Natural Resources Districts, numerous state agencies and the state's citizens to find solutions to pressing water issues, educate the public and policymakers about such issues, and advance Nebraska's water stewardship efforts.

"It's important that we work with producers, the NRDs and other groups to solve our water problems. This has to be a collaborative effort," said Chittaranjan Ray, director of the Nebraska Water Center.

One result of this collaboration is the ability to place experts in the field in the greatest areas of need. IANR is partnering with the NRDs to hire a water quality expert who will be based in northeast Nebraska, where nitrate contamination is a serious concern. While the focus will be on improving water quality, the position is also expected to raise awareness of the importance of water stewardship in the area.

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