Saltwater Intrusion

The landward movement of seawater into coastal communities is causing salt damage to land along the eastern seaboard of the United States. For coastal communities like on Maryland's rural Lower Eastern Shore, that can mean invasive marsh species, undrinkable water, damaged forests, reduced agricultural crop yields, and salt-stressed soils. This study performed by University of Maryland scientist Dr. Kate Tully and partially funded by the Harry R. Hughes Center for Agro-Ecology looks into ways we could potentially mitigate this phenomenon called saltwater intrusion brought on by sea-level rise and climate change.

The project, led by University of Maryland (UMD) scientist Dr. Kate Tully in conjunction with Dr. Dani Weissman and researchers from the University of Delaware and George Washington University, was submitted by the Harry R. Hughes Center for Agro-Ecology to the National Fish and Wildlife Foundation and recently awarded a $469,888 grant through the Chesapeake Bay Stewardship Fund.

“Although the fieldwork for this research is being performed on the Lower Eastern Shore in Dorchester and Somerset counties, saltwater intrusion is degrading coastal farmlands across the northern seaboard,” said Dr. Kate Everts, director of the Hughes Center and the UMD Wye Research and Education Center. “The Hughes Center is proud to be working with Dr. Tully at the forefront of addressing this issue.”

The Eastern Shore of Maryland is very low-lying and as sea levels rise, saltwater can move easily into groundwater as well as through the extensive ditch network used by farmers. Impacting both farmers and the natural resources of the land, it can lead to issues like decreased yields, salt-tolerant invasive species, coastal forest losses and marsh migrations.

“Saltwater intrusion is like an invisible flood. It salinizes the water table under the soil surface making the field inhospitable to our typical agricultural crops, which prefer fresh water. Our research shows that it is currently affecting far more land than what is projected by shallow coastal flooding alone,” Dr. Tully said. “Saltwater intrusion can kill crops and forest, has the potential to unlock pollutants from the soil, and is literally drowning our history.”

Dr. Tully, associate professor of agro-ecology at the University of Maryland and director of the AgroEcoLab, and her team has been studying saltwater intrusion on the Lower Eastern Shore of Maryland under prior grant awards since 2017.

Research funded under this new NFWF grant will evaluate native perennial grass species for their ability to establish along the margins of farm fields affected by saltwater intrusion. The researchers hope that by establishing native perennial grasses, it can prevent sediment and nutrient pollution to the Chesapeake Bay while at the same time provide habitat for species like the American Black Duck.

“On lands that are degraded by saltwater intrusion (SWI), it can be difficult to make money farming our typical crops of soy and corn. If we are able to restore these lands to native grasses successfully, we hope to work with agencies like the Maryland Department of Natural Resources and Maryland Department of Agriculture to develop new easement opportunities for farmers battling saltwater intrusion. Native grasses are more salt-tolerant and they are deeply rooted, which means they are likely to be more successful than annual rotations once fields are intruded by saltwater,” Dr. Tully said.

The project also will create complete maps of land in Somerset and Dorchester counties to identify priority areas at risk of saltwater intrusion and areas for tidal wetland habitat creation, and also implement wetland restoration projects on 32 acres of farmland.

“Currently, we don't have a suite of options for our Lower Eastern Shore farmers who want to face saltwater intrusion head-on. This research will provide much-needed data on how best to restore damaged agricultural lands to wetlands for both pollution reduction and improved habitat,” Dr. Tully said.

Dr. Kate Tully joins WNAV's Donna Cole in the studio for a discussion about the work she's doing with saltwater intrusion on Eastern Shore farms.