Long time-series of water levels in major aquifers serve as critical baseline data for resource management and analyses of aquifer response to pumping, climatic variability, drought hazards, seawater intrusion, and interaction with streams and their ecosystems. To this end the Delaware Geological Survey (DGS) currently monitors groundwater level, temperature, and salinity in a network of wells in Delaware. The number of wells fluctuates annually with funding and staffing resources. Data from network wells are maintained in a relational database and served to stakeholders via a web interface. As of December 2020, the DGS database holds over 27 M instrument measured and nearly 63 K manually measured groundwater levels. Instrumentation has generated over 7.4 M temperature and 3.8 M specific conductance records.  These data support evaluation of the long-term availability and sustainability of Delaware’s groundwater supply, management of the resource, and a myriad of uses by the environmental management, engineering, and research communities.

Recent projects done at the request of the Delaware Water Supply Coordinating Council (WSCC) added more than 20 wells to the network in southern New Castle County and nearly 50 additional wells in Kent County. As part of these projects we have automated data collection, reduction, and archiving to increase efficiency and quality control while sustaining the statewide network over time. We are inspecting the condition of wells in the current monitoring network in addition to inspecting wells that may be included at a later date, using down-hole videos, slug tests, and wellhead security assessments.

In anticipation of needs to monitor for saltwater instrusion we deployed and are testing operations of salinity sensors in several wells along the Atlantic and Delaware Bay coasts.  In early 2021 we acquired resources to expand monitoring to include routine groundwater quality sampling and analyses.