CAPE MAY, NJ – If you look up in the sky over South Jersey, you’ve probably seen strange helicopters. Sightings have been reported across the state, but this week, they have increased over the Delaware Bay region of South Jersey and Delaware.

The helicopters are carrying large rings that resemble hula hoops as they fly low to the ground. Sometimes just 100 feet above the ground, flying low around woodlands and neighborhoods. But what are they and why are they here?

According tot he U.S. Geological Survey, they’re testing underground water salinity.

“Starting around July 8 and lasting up to a month, a helicopter towing a large hoop from a cable will begin making low-level flights over Delaware Bay and nearby regions in Delaware and New Jersey as part of the U.S. Geological Survey’s Next Generation Water Observing System project in the Delaware River Basin,” the USGS said. “USGS scientists and researchers from the University of Delaware will use the data to improve understanding of groundwater salinity and below-ground geology.  Rising sea level, increasing frequency and intensity of coastal storms and increasing demand for groundwater have amplified the risk of saltwater impacting water supplies in the region.”

The USGS says the data from this survey will serve as a benchmark against which future changes in groundwater salinity in the Delaware Bay region can be compared. 

“The helicopter will fly along pre-planned flight paths relatively low to the ground at 100-200 feet above the surface. A sensor that resembles a large hula-hoop will be towed beneath the helicopter to measure tiny electromagnetic signals that can be used to map features below Earth’s surface. Flight lines will be separated by about 1/3 mile near shore and just under two miles crossing over Delaware Bay, so the helicopter system will be visible from any location for a short period of time. Several flight lines will follow nearby river paths to map the extent of saline water upstream,” the USGS reported.

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