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Nutrient Loading From Groundwater And Its Role In TMDL’s

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Pp. 262-267 in Total Maximum Daily Load (TMDL) Environmental Regulations: Proceedings of the March 11-13, 2002 Conference, (Fort Worth, Texas, USA)  701P0102.(doi:10.13031/2013.7567)
Authors:   Robert M. Roseen, Larry K. Brannaka, Thomas P. Ballestero
Keywords:   Thermal Infrared, Groundwater Discharge, Nutrient, Pollution, Coastal Management, Coastal, Estuary

Nutrient loading of coastal waters from groundwater discharge is a significant problem that historically has been very difficult to quantify. Current research shows that groundwater may constitute as much as 40% of the total freshwater discharge into coastal waters and capable of carrying a significant nutrient load. Our research in coastal New Hampshire, using recent advances in thermal imagery and field techniques, indicates that groundwater is one of the dominant sources of nitrogen and on par with major tributaries. Coastal managers have the difficult task of identifying, prioritizing and mitigating coastal and estuarine contaminant sources. Regulators and resource managers must quantify each contaminant source in order to accurately determine Total Maximum Daily Loads (TMDLs). Recent advances in thermal infrared imagery provide an affordable tool with which to evaluate groundwater contamination. Contaminant loading estimates are an integral part of effective resource management allowing managers to prioritize efforts based on the size and relative importance of the source. Tools that can simplify the increasingly complicated task of resource management for coastal managers are invaluable. In coastal areas where shallow unconfined aquifers predominate, significant flow occurs through transmissive materials (sands and gravels), discharging groundwater into coastal waters. The EPA has identified nonpoint sources such as underground storage tanks, septic systems, landfills, and agriculture lands as the primary sources of groundwater contamination. Thus, in coastal communities where these nonpoint sources are prevalent, groundwater may be transporting significant nutrient concentrations that contribute to the degradation of estuarine and coastal health. New methodologies to accurately assess contaminant loading from groundwater will improve the determination of TMDLs and ultimately the protection and preservation of estuarine and coastal waters.

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