DELAWARE’S GROUNDWATER MONITORING NETWORK: A MULTI-DIMENSIONAL NETWORK FOR MANAGING A SUSTAINABLE GROUNDWATER SUPPLY

Delaware is the second smallest state in the U.S., with an area of 1,955 square miles. But Delaware “punches above its weight” in terms of the density of wells, and data provided by its groundwater monitoring network. The hydrogeology of Delaware includes crystalline bedrock aquifers in the Piedmont Province in the northern part of the state, with the majority of the state's groundwater derived from confined and unconfined aquifers in the coastal plain. The Delaware groundwater monitoring network consists of 133 wells, which includes 122 operated by the Delaware Geological Survey (DGS), and 11 wells managed by cooperating partners. Many of the monitoring sites across the state have well nests with multiple wells that monitor layered aquifers. In total, the network monitors 15 major aquifers.

Ninety-six wells have continuous water-level data recorders, with the remaining wells measured quarterly in the field. Currently, 11 wells provide real-time data, with seven wells equipped with real-time equipment operated by DGS, and the remaining four wells managed by cooperating agencies. The DGS contributes data to the USGS National Groundwater Monitoring Network (NGWMN) and has received financial support for continuous data recorders.

DGS also samples 74 wells for major ions and trace metals. Three wells located along the coast have continuously-recording electrical conductivity data loggers that monitor salt-water intrusion. Recently the DGS has received funding from the state to install 48 additional wells to expand the groundwater network in Sussex County, which comprises the southernmost part of the state and is experiencing significant population growth in coastal communities. DGS is using current network water-quality data to select locations for prospective new wells to monitor potential salt-water intrusion. The DGS works closely with the state climatologist and the Delaware Environmental Operating System (DEOS), which manages 80 environmental monitoring and weather stations across the state that provide valuable precipitation, temperature, and ET data that is integrated for evaluating groundwater conditions for the state. DGS and DEOS are major partners that advise the state’s emergency management agency, as well as the Governor’s Water Supply Coordinating Council regarding water availability and drought conditions for the state.