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July 10, 2014
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Groundwater study underway in Upper Delaware

A scientist in a kayak tows an electromagnetic-induction tool that measures changes in the sediment beneath the river within several meters of the riverbed. A seepage meter designed to measure the amount of water flowing across the riverbed is visible in the foreground.

The project is designed to look at the distribution of groundwater as it discharges to the Delaware River. “The people who live here and fish here know to a large extent where the groundwater is focused,” said Rosenberry. “They know that groundwater is discharging to the river, but they probably don’t think about what it means. We do. This is the kind of work that USGS does all across the country.

“As a country, about 40% of the water we consume comes from groundwater. In rural areas, that percentage is much larger. The concern is that as we use more groundwater to supply our homes and infrastructure, there may be less groundwater discharging to the river. So at times when the river temperature is very warm, the fish and the animals that live in the substrate may become stressed.”

USGS staff have also been sampling the chemistry of several small hand-augured wells that they installed in the river bed and along the shore to determine the chemical inputs to the river. Several wells with sensors inside will continue to collect data every 20 minutes throughout the year.

Gathering such data now establishes a baseline against which changes can be measured in the future. “It’s not just people who make use of groundwater,” said Rosenberry. “It’s also the natural environment. Animals that live in the substrate, macroinvertebrates and plants — there are many microenvironments that rely on this. We don’t always think about that. This kind of work will set a baseline we can compare to years from now.”

The USGS produces numerous reports for the public in addition to those for its scientific colleagues. Two of particular relevance to this topic can be seen at and