Learning from Lakes

MAFES scientists work to manage nutrients in Mississippi's waters

By: Vanessa Beeson

Learning from Lakes

Mississippi State students canoe in the Mississippi River during Spring Break. (Photo by Megan Bean)

Carolina Kelsoe grew up in Rainbow City, Alabama but it was three years in the Middle East that got the agricultural economics master's student interested in water. From the ages of 12 to 15, Kelsoe and her family lived in Jordan where her parents were employed. She said living in a place where water was scarce made her think about the world's most important natural resource in a different way.

"Seeing how water is managed under scarcity and then returning to the South was an eye-opener for me. It's fascinating because we view water differently and that shows in the way we manage it as a resource," Kelsoe said. "Mississippi is an interesting place to study water because there are so many facets of water quality and management. It's something that I've been personally interested in for a while and I am excited I can also pursue the interest academically."

Kelsoe came to Mississippi State to pursue a bachelor's in environmental economics and management. She stayed on for a master's, which she plans to complete in August 2019. After that, she will continue on at University of California at Davis working toward a doctoral degree. Currently, she's under the direction of Dr. Matthew Interis, associate professor in the Department of Agricultural Economics, studying numeric nutrient criteria in Mississippi's lakes.

Kelsoe and Interis are working on a project in consultation with the Mississippi Department of Environmental Quality, or MDEQ, a state agency that has been tasked with developing numeric nutrient criteria.

"Numeric nutrient criteria means establishing an allowable threshold of nutrients in a body of water. Nutrients are good but nutrients in excess have been linked to such things as algae blooms, foul odors, and reduced clarity in bodies of water," Kelsoe said.

Through its Water Quality Standards Program, the MDEQ seeks to develop numeric nutrient criteria for Mississippi's waters.

"The MDEQ is trying to establish a threshold where nitrogen or phosphorus may start to cause problems and may then limit excess nutrients beyond that threshold for the health of Mississippi's lakes, rivers, and streams," Kelsoe explained. "They also plan to help water-bodies that have surpassed this threshold by determining and implementing best practices that reduce the polluted runoff entering the system."

Interis said MDEQ will establish four sets of numeric nutrient criteria: one for lakes and reservoirs; one for rivers and streams; one for estuarine, or coastal waters; and one for water-bodies in the Delta region.

Interis said MSU has partnered with MDEQ on several research projects to help the agency create effective scientific-based water quality standards. He explained the objectives of this particular study.

"As economists, we're interested in the benefits and costs of MDEQ's proposed policy as measured in dollars, so our study looks at one part of the presumed benefits of the policy: reduced nutrients in Mississippi lakes," he said.

He continued, "When it comes to policy design and implementation, of course, there are other concerns besides economics. For example, the EPA has encouraged states to develop numeric nutrient criteria and many states in the Mississippi River Basin are developing a work plan."

Interis said the bigger picture comparison of benefits and costs includes the benefits of reduced nutrients in the Gulf of Mexico and in rivers and streams, and the costs to agricultural producers or municipalities of reducing nutrients in Mississippi water-bodies.

"Our study is one piece of this benefit-cost puzzle where we try to determine if the benefits of a numeric nutrient criteria policy outweigh the program's cost when it comes to recreational lakes," he said.

The team chose to study lakes as opposed to rivers, streams, or the Gulf, because the impact of nutrients are more evident in the short term.

"It can take many years to see impacts in rivers and streams or in the Gulf, but with lakes, we might see a change in a season or two if this policy is enacted," Interis said. "This is a relatively small project that could be extended to include rivers, and streams, and even the Gulf."

The team surveyed Mississippians who visited lakes throughout the state for recreation in May through October 2017, asking lake visitors which lakes they visited and how frequently they visited each. They collected data on approximately 100 lakes. They then compared the survey information with available water quality data for the corresponding lakes, focusing on phosphorus as a measure of water quality.

While there was only water quality data available for approximately one third of the lakes, the team partnered with Dr. Seong Yun, also in the Department of Agricultural Economics, to build a model that predicted water quality for the remaining lakes based on the available data, with assistance from Dr. Prem Parajuli in the Department of Agricultural and Biological Engineering and Dr. Padmanava Dash in the Department of Geosciences. After predicting water quality for lakes with missing data, Kelsoe and Interis will use an economic model to estimate a dollar amount recreational lake visitors are willing to pay for better water quality.

"The crux of this project is what kind of recreational value do people gain from water quality? Are they willing to pay more to travel to a higher quality lake? The model we use is based on the intuition that a person will choose to visit a lake based on characteristics of the lake such as boat ramps, guest services, and water quality and that people are sometimes willing to drive farther, thereby incurring additional costs, to visit a lake with better characteristics," Kelsoe said.

Interis said that while more water quality data would help make the estimation more accurate, their analysis will provide an initial estimate of the dollar value of reducing phosphorus in recreational lakes in Mississippi. With additional studies estimating the value of reduced nutrients in rivers and streams and in the Gulf of Mexico, and of the costs of reducing nutrients, a more complete assessment of the overall benefits and costs of numeric nutrient criteria in Mississippi can be made.

"We've used known water quality of existing lakes and the land use and other characteristics in their surrounding area to estimate water quality in different lakes with their respective land use characteristics. This helps us predict what water quality should be for a particular lake. In the future, if an interdisciplinary team can collect water quality data for all of these lakes, we can then improve our estimates with the additional data," Interis explained.

For now, Interis said the team hopes to provide concrete economic data for MDEQ.

"The idea is to compare costs and benefits of nutrient reduction in lakes to see if enacting the policy makes economic sense," Interis said.

The lake nutrient management project is funded by the MAFES Strategic Research Initiative.

To protect coastal waters, MAFES partners with 12 other land-grant universities through the SERA-46/Hypoxia Task Force multistate project. SERA-46 is the Southern Extension and Research Activities committee number 46 and is one of a group of formal USDA National Institute of Food and Agriculture and land-grant university funded committees designed to promote multi-state research and extension activities. SERA-46 was created to operationalize a cooperative agreement between the Mississippi River Gulf of Mexico Watershed Nutrient Task Force (Hypoxia Task Force) and land-grant university extension and experiment stations in the north, central, and southern regions of the United States.

Excessive nutrient loadings within the Mississippi/Atchafalaya River Basin are a leading cause of Gulf of Mexico hypoxia. SERA-46 brings together researchers and extension personnel from fifteen states throughout the basin and across the northern Gulf to develop and implement consistent, correlatable measures to track progress in the human dimension of reducing excessive nutrient loads.