New Research to Consolidate Tools to Manage Salt Contamination of Fresh Water Supplies

Salt contamination of water supplies in tidal rivers is a growing problem around the world, threatening the safe drinking water of billions of people. A multi-institution research group of scientists and engineers led by the University of Maryland Center for Environmental Science (UMCES) has been awarded a $650,000 Phase 1 grant by the US National Science Foundation's (NSF) Convergence Accelerator to develop and prototype tools to help monitor and manage decision-making around this emerging issue.

“More and more communities are looking for information on rising salt in their freshwater sources. But we don’t just want to provide data; we want to share that data in a way that makes it really useful,” says Assistant Professor of City & Regional Planning Allison Lassiter, one of the co-principal investigators. “Working alongside water users and co-developing the interface of the salinity prediction tool is essential to move from data into action.”

As the project lead for stakeholder engagement, Lassiter will be talking with water users, state regulators, and environmental agencies to develop new tools to help communities anticipate and plan for increasing salt in their drinking water.

About 70% of the US drinking water supply comes from surface waters, including tidal rivers, which are the tidal fresh region of estuaries. Drought and sea level rise, which lead to saltwater intrusion from the ocean, and changes in land-use, which lead to freshwater salinization, are putting water resources at risk. The risk extends to water uses for thermoelectric power, irrigation, and industrial production. This topic made headline news in recent years, including the Mississippi River in 2023, the Rhine River in 2022 and the San Francisco Bay-Delta in 2021.

The NSF-supported work is led by oceanographer and UMCES Professor Ming Li. “Both developed and developing countries are struggling with salt contamination of tidal river waters and many rely on numerical models to manage salinity,” said Li. “These new tools will be applicable to numerous systems around the globe.”

Many water suppliers, for example, do not have the necessary planning and technical capacity to prepare for these changes. To that end, this project team will develop and prototype decision support and monitoring tools for salinity management by working with water resource managers, under-resourced rural communities, and water suppliers. The goal is to create a better decision support system for salinity management and coastal communities to bolster the resilience of water infrastructure and protect public health.

Indeed, tidal rivers like the Susquehanna and Potomac are already encountering high chloride levels in water supplies that are impacting drinking water quality for public consumption. Rural communities such as Havre de Grace and Perryville withdraw drinking water from the Susquehanna River; their drinking water intakes were threatened by high chloride levels during periods of extended drought. Farmers who withdraw water for irrigation also competed for the scarce freshwater resources. In the Potomac River, use of road deicers during winter storms and human-accelerated weathering have led to freshwater salinization near densely populated areas, adding to the increasing problem of oceanic salt intrusion. Better modeling and monitoring tools are needed to manage this contamination.

Li’s team will develop a new coupled watershed–estuary model that simulates the transport and fate of major salt ions by leveraging recent advances in hydrological and estuarine modeling, using the Chesapeake Bay and its tidal rivers as a pilot-study site. The model will then be used in combination with artificial intelligence algorithms, in a planning tool to identify management strategies and quantify the tradeoffs between competing needs for freshwater resources. This approach will also be used to search for long-term planning strategies in the form of adaptation pathways.

Additional institutions contributing to this effort include Pennsylvania State University, University of Maryland College Park, Salisbury University, Rutgers University, Izaak Walton League of America, Maryland Department of the Environment, Maryland Department of Planning, Maryland Geological Survey, Metropolitan Washington Council, Interstate Commission on the Potomac River Basin, Susquehanna River Basin Commission, Delaware River Basin Commission, EPA Chesapeake Bay Program, and Maryland Sea Grant. This research is funded by the NSF’s Convergence Accelerator’s Track K: Equitable Water Solutions.