Monitoring wells and groundwater sensors were installed and monitored in and around Holts Landing State Park on the Indian River Bay, eastern Sussex County, Delaware, between October 2009 and August 2012. Data from test drilling, geophysical logging, geophysical surveys, and well testing characterized the hydrogeological framework and spatial and temporal patterns of water pressure, temperature, and salinity in the shallow, unconfined Columbia aquifer. The work revealed a plume of freshened groundwater extending more than 650 ft into the bay from the shoreline.

The geological history of the surficial units of the Seaford East Quadrangle and the Delaware portion of the Seaford West Quadrangle was the result of deposition of the Beaverdam Formation and its subsequent modification by erosion and deposition related to sea-level fluctuations during the Pleistocene. The geology reflects this complex history by the cut and fill geometry of the middle and late Pleistocene deposits incised into the Beaverdam Formation.

This report presents a conceptual model of groundwater flow and the effects of nitrate (NO3-) loading and transport on shallow groundwater quality in a portion of the Indian River watershed, eastern Sussex County, Delaware. Three-dimensional, numerical simulations of groundwater flow, particle tracking, and contaminant transport were constructed and tested against data collected in previous hydrogeological and water-quality studies.

The geological history of the surficial geologic units in western Sussex County is that of deposition of the Beaverdam Formation and its subsequent modification by erosion and deposition related to the sea-level fluctuations during the Pleistocene. The geology reflects this complex history by the cut and fill geometry of the middle and late Pleistocene deposits into the Beaverdam Formation. The geology is further complicated by periglacial activity that produced dune deposits and Carolina Bays in the map area, which modified the land surface.

The geological history of the surficial units of the Trap Pond and the Delaware portion of the Pittsville Quadrangle was the result of deposition of the Beaverdam Formation and its subsequent modification by erosion and deposition related to the sea-level fluctuations during the Pleistocene. The geology reflects this complex history by the cut and fill geometry of the Middle and late Pleistocene deposits into the Beaverdam Formation. The geology is further complicated by periglacial activity that produced dune deposits and Carolina Bays in the map area, which modified the land surface.