Merrimack River Estuary Dye-Tracer Study
High levels of fecal coliform bacteria enter the Merrimack River estuary, primarily from stormwater runoff and upstream community combined sewer overflows. Accurate assessment of the impact of each suspected source requires knowledge of time-of-travel, residence time, and dispersion of wastewater discharges and runoff. Assessing the time-of-travel in the Merrimack estuarine reach is complicated by the complex, unsteady, and oscillatory stage and flow patterns that occur due to tides and saline stratification. A conservative dye tracer was used to track the movement and mimic the dispersion of a solute (bacteria) in the Newburyport tidal basin in the Lower Merrimack River. Preliminary results indicate a circulation pattern in the estuary that may have an impact on the recently opened clam-flats.
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