The Geology of Delaware

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Introduction to the Hydrogeology of Delaware

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Brandywine Creek

Delaware’s water, both ground and surface, is one of its most important natural resources. It is essential for meeting the needs of all segments of our society and for maintaining economic growth and agriculture. At this time, all water used for public and domestic supply and more than 98% of water used for irrigation south of the Chesapeake and Delaware Canal is groundwater. North of the canal, approximately 70% of public water supplies are obtained from four surface-water sources (creeks) and 30% from groundwater resources.

Because of the importance of groundwater to the State, hydrogeologic programs and studies are a major focus of DGS staff. Recent and ongoing efforts include such subjects as ambient and targeted groundwater level and quality monitoring, mapping of aquifer extents and hydraulic properties, assessing the impacts of artificial drainage and wastewater disposal practices, developing methods for remote sensing of groundwater discharge areas, and development of techniques for storage, analysis, and distribution of groundwater information by geographic information systems.

The DGS is the lead agency for collection and analysis of data on groundwater levels and stream discharges in Delaware. The importance of water conditions monitoring has been highlighted in the last several years by a series of droughts and floods. We operate and monitor a variety of systems that provide water-conditions data and capture these data in an Oracle-based hydrological data management system. Groundwater conditions are monitored by a statewide water-level monitoring network of 69 wells. In addition, in 1985 the DGS implemented a water level and chloride monitoring program for 25 wells along the Atlantic Coast to evaluate the potential for salt-water intrusion in aquifers used for public and domestic water supplies. Surface-water conditions are tracked for 15 stream-gage and 10 tide-gage stations around the state. The stream-gaging network was begun by the USGS in 1931 and is now operated cooperatively between the DGS and the USGS.

DGS staff participate in programs and projects related to surface water resources of Delaware and the Delaware River Basin. For example, the DGS coordinates these efforts for the state and facilitates acquisition of streamflow and tide-gage data for Delaware stakeholders. Staff members have also been principal investigators in multi-disciplinary, multi-agency studies to evaluate the fluxes of water, plant nutrients, and other dissolved and suspended sediments in the Inland Bays and Nanticoke River watersheds. As Delaware’s lead earth science agency, the Delaware Geological Survey provides information to inform and educate resource managers and the public to better understand and manage our water resources. The Delaware Geological Survey, by statute, manages and provides liaison for all state-federal projects related to the DGS-USGS Joint-Funded and Partnering Programs.

Data and Graphs about Water in Delaware