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"Delmarva Potholes" and Other Threatened Wetlands and Streams

Tom Pelton

I’m on the Eastern Shore of Maryland, near Denton, standing in a forested wetlands surrounded by miles of corn and soybean fields. Here, in this little island of biodiversity, sweetgum trees and bald cypresses rise up from coffee-colored water.

A gentle wind sways the branches, leading spots of light and shadow in a dance over the surface of the water, illuminating tufts of grasses and rotting logs that are home to salamanders and frogs.

This place is what is called a “Delmarva Pothole” or “Delmarva Bay.” They are small, isolated, fresh water wetlands that are connected only beneath the ground to nearby streams and rivers.

Although few outsiders have ever heard of them, biologists say these potholes – which locals call “whale wallows” -- provide invaluable ecological services for the Chesapeake Bay by filtering runoff pollution being washed by rain off of farm fields.

Andrew Baldwin is a professor of wetland ecology at the University of Maryland College Park.  “So they are important.  They often harbor rare plant and animal species as well as other common wetland and non-wetland plants,” Baldwin said. “They are good for birds and other organisms.”

Organisms, including humans, Baldwin notes, because “Delmarva Potholes” act like sponges to absorb floodwaters that might otherwise overwhelm our homes and towns.

But research by Baldwin’s colleagues at the University of Maryland show that these “Delmarva potholes” have also been disappearing over the centuries, as farmers drain them, fill them, and plow them under for farm fields. 

According one aerial study published in the journal Wetlands, there were once 119,000 acres of “Delmarva Potholes” across the Delmarva Peninsula. But that total has since declined by about two thirds, to about 35,000 acres.

Recognizing the need to protect isolated wetlands like this across the U.S., the Obama Administration in 2015 imposed new regulations called the “Waters of the US Rule.”

But then the Trump Administration last year announced it would delay and roll back these protections, which are opposed by both the agricultural industry and real-estate developers who want to build subdivisions on farmland.

On August 16, a federal judge in South Carolina dealt a blow to the Trump Administration’s de-regulatory efforts. The judge issued an injunction ordering the “Waters of the US Rule” to immediately take effect in 26 states – including Maryland, Pennsylvania, Virginia and Delaware.

Bob Irvin, president of the advocacy group American Rivers, said the ruling was important because it also protects intermittent or seasonal streams.

“The decision in South Carolina was a major victory for rivers, clean water and the protection of wetlands and headwater streams,” Irvin said.

However, the victory may prove a temporary one.  The Trump Administration has indicated it plans release new regulations this fall that could once again strip away protections for isolated wetlands and intermittent streams that serve as the filters and headwaters for many drinking water supplies.

Navis Bermudez is federal legislative director for the Southern Environmental Law Center.

“I think if people care about clean water, and access to clean water, they should care about this issue,” Bermudez said. “If you like to paddle or boat in a water body, you should care about this issue. Approximately 117 million Americans get their drinking water from a small stream that may no longer be protected if the Trump Administration’s ultimate plan is finalized.”

So, Delmarva potholes and other threatened wetlands are not yet out of the woods.

Tom Pelton, a national award-winning environmental journalist, has hosted "The Environment in Focus" since 2007. He also works as director of communications for the Environmental Integrity Project, a non-profit organization dedicated to holding polluters and governments accountable to protect public health. From 1997 until 2008, he was a journalist for The Baltimore Sun, where he was twice named one of the best environmental reporters in America by the Society of Environmental Journalists.