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Climate Change


Delaware's water resources

Delaware’s beautiful water resources, most notably the Delaware Bay estuary, provide critical habitat for an abundance of fish and wildlife, as well as ample recreational opportunities for the pubic such as fishing, boating, bird-watching, and beachgoing. Delaware’s groundwater system also provides a large component of the state’s industrial and municipal water supply.

However, changes in temperature, precipitation, and sea level from climate change could impact the region’s hydrology, leading to reduced stream and river flow, lower aquifer recharge rates, reduced water supply, and negatively impact the ecology of Delaware’s forests, wetlands, and estuarine habitat.


The Northeast Climate Impacts Assessment (NCIA) discusses a number of ways climate change is projected to affect the water resources in the Northeast. For example, climate change will likely bring increased precipitation over winter and spring, increasing stream flow and groundwater supply during these months, while at the same time increasing the risk of winter flooding. The increased winter precipitation is expected to fall mostly as rain, and warmer winter temperatures will shorten the snow season and reduce snowpack in many northern states.

The Delaware River is the greatest freshwater resource for the Delaware Estuary, which in turn provides expansive habitat for fish and wildlife.

But rising temperatures and increased incidence of short-term droughts could cause extended low-flow periods in the summer, increasing the risk of water supply shortage problems during the summer and fall months.

Delaware’s 132,000 acres of freshwater wetlands are one of the most biologically productive ecosystems, providing a host of benefits, including filtering pollutants from the water, providing protection from flooding, and supplying wildlife habitat. Reduced water supply, poorer water quality, and sea level rise from climate change could threaten Delaware’s wetlands and degrade their ecological functionality.

While drought conditions may become more frequent over the hotter months of the year, heavy rain events have the potential to increase surface runoff. More storm water runoff will increase the risk that surface water supplies from lakes, rivers, ponds, and reservoirs could be contaminated from sewage, agriculture and industrial pollutants. According to the US Environmental Protection Agency (USEPA, 1997), many of Delaware’s shallow aquifers already are contaminated by industrial pollutants, and increased precipitation could contribute to groundwater contamination by increasing the inflow of contaminants into the state’s aquifers.


While groundwater supplies have become increasingly important in providing public drinking water, coastal areas are under increased threat of saltwater contamination from sea level rise. Saltwater intrusion occurs when excessive pumping from coastal aquifers decreases the pressure gradient between underground freshwater and ocean saltwater.

As freshwater is pumped from the underground aquifers to the surface, saltwater is drawn in to the aquifers, leading to contamination. Coastal areas along the Northeast, including southeastern New England, Massachusetts' Cape Cod area and New Jersey, are already experiencing saltwater intrusion problems (NECIA, 2007).

For example, pumping in Camden, N.J. has reduced groundwater levels enough to cause brackish water from the Delaware River to flow into the aquifer.

New Jersey's Cape May Peninsula also has experienced reduced groundwater supplies and subsequent saltwater intrusion, forcing water suppliers to move their wells inland.

Given the Intergovernmental Panel on Climate Change’s projections of a 7-23 inch sea level rise by the end of the century, depending on future emission scenarios, Delaware’s shallow groundwater supplies may be at risk from saltwater intrusion.











SALT WATER INTRUSION: The figure above shows selected areas along the Atlantic coast where saltwater has intruded upon coastal freshwater aquifers. Future population growth and projected sea level rise will likely increase stresses on coastal aquifers and on the ecosystems that depend upon freshwater discharges from these aquifers. Source: USGS, Ground Water Resources Program.


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