The Mississippi Department of Environmental Quality, supporting the Gulf of Mexico Alliance’s Nutrient Team, tasked Tetra Tech, Inc. to design and implement a monitoring and modelling project. Their paper, “Modeling the Factors Controlling Phytoplankton in the St. Louis Bay Estuary, Mississippi and Evaluating Estuarine Responses to Nutrient Load Modifications” recently won the prestigious Greeley Award from the American Society of Civil Engineers (ASCE).

The ASCE Environmental and Water Resources Institute initiated the Samuel Arnold Greeley Award in 1968. ASCE may give the award annually to the author(s) that make the most valuable
contribution to the environmental engineering profession. The winning manuscript was based on the project, “Sources, Fate, Transport, and Effects (SFTE) of Nutrients as a Basis for Protective Criteria in Estuarine and Near-Coastal Waters, Saint Louis Bay, Mississippi Pilot Study.”

Tetra Tech coordinated with the USM Gulf Coast Research Laboratory, to conduct field sampling and environmental measurements over a 12-month period. The suite of data collected included hydrodynamic, meteorological, field and laboratory water chemistry, tidal features, and freshwater inflows. The team also collected benthic biological characteristics and summarized them with the Nutrient Team’s Gulf Benthic Index.

Tetra Tech used a modelling approach that linked models on watershed loading (LSPC), hydrodynamic (EFDC), and water quality for Saint Louis Bay and its contributing watershed (WASP version 7.41). The work was calibrated with the detailed and comprehensive water quality data.

The team analyzed the data and conducted extensive modelling of the interrelationships among all the factors. The results inform the development of objective, numeric thresholds of nutrient concentrations for the protection of aquatic life.

The U.S. EPA Gulf of Mexico Program funded the project. Congratulations to all the partners. The paper, published in the ASCE Journal of Environmental Engineering, can be accessed in the ASCE Library. For more information, contact the lead author Rene A. Camacho. To learn more about this effort or get a copy of the final report, contact the Water Resources Team.