Flooding the Swamp

Reversing a legacy of ditching and draining, we’re reconnecting the Pocomoke River to its floodplain wetlands to enhance water quality and habitat.


By Severn Smith on August 28, 2017

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Civilian Conservation Corps members dig ditches along the Delmarva Peninsula August 1935.  Photos by Jack Hutmacher / provided courtesy of Dr. Dennis Bartow

“Draining the swamp” has been used as a murky political metaphor since Washington, DC was identified as the seat of government of the newly-formed United States of America in the late 1700s. The land, a tidal marsh of the Potomac River, had to be partially drained before Pierre L’Enfant’s vision for the nation’s new capital district could take shape.

Since then, the metaphor has been used by politicos and commentators of all stripes to disparage opposing viewpoints. But ask a conservation scientist about the term and you’re likely to see him or her cringe, then describe in detail the importance of swamps, also commonly called wetlands or marshes. That’s what happened when I asked Dr. Kathleen Boomer, Watershed Scientist for The Nature Conservancy, why the Conservancy is working to restore the Pocomoke River’s floodplain cypress swamp, which was drained in the mid-20th century.

“When you think about how water moves across a landscape,” says Dr. Boomer “it becomes clear that floodplain wetlands play a critical role storing and filtering water.” During large storms, rivers like the Pocomoke overflow their banks into the adjacent lands, or floodplain.

Outside of a river’s main channel, the water spreads out and is slowed by vegetation. Sediment settles out of the water, and nutrients in the water are used by plants and trees in the floodplain to grow. After the storm, when the river’s water level subsides, the “filtered” floodwaters slowly return to the river. The whole process helps to reduce erosion and improve water quality.

Floodplains also provide important aquatic habitat. In the Pocomoke’s floodplain swamps, the saturated soils support some of the most biodiverse wetland habitats in the region. The foundation of this rich habitat, towering over much of the Pocomoke’s floodplain, are stately cypress trees that conjure an image more resembling a Louisiana Bayou than the Eastern Shore of Maryland. 


DRAINING THE SWAMP

 

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The 73-mile-long Pocomoke is the easternmost river that flows into the Chesapeake Bay, draining water from four counties in three states. The Pocomoke River system’s headwaters form in the Great Cypress Swamp in southeastern Delaware. From there, the river slowly meanders south across the flat, Eastern Shore of Maryland, and finally into Virginia where it empties into the Pocomoke Sound, and ultimately the Chesapeake Bay.

Historically, rain that would fall within the Pocomoke’s watershed would filter into the ground, then slowly seep into the river and its tributary streams. That natural process started to become disrupted after European settlers began ditching the land to facilitate development and agriculture.

Fast forward a few hundred years to just after World War II, and agricultural ditching dramatically increased to meet the food demands of a booming population.

While the surrounding cropland was being ditched to more rapidly transmit water off the land after heavy storm events, an 18-mile section of the Pocomoke River mainstem was dredged and channelized. The dredged material was piled along each side of the river’s edge creating “spoil banks,” making it even more difficult for floodwaters to exit the channel, further disconnecting the river from thousands of acres of floodplain.


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Excerpt from a 1946 announcement explaining the initial rationale for channelizing the Pocomoke River.

The announcement of a ribbon cutting ceremony initiating the dredging of the Pocomoke in 1946 provides a perspective from Delmarva at that time: “The flat farmland in this area must be drained by ditches which empty into the Pocomoke River. After hard rains the water backed up into the drainage ditches, and fields were sodden for days, making the ground barren and unprofitable as farmland.”

Today, consequences of the Pocomoke Drainage Project are apparent: “The ditching of the Pocomoke floodplain, and the channelization of the river, converted what was historically a groundwater-dominated system into a surface water-dominated system,” says Dr. Boomer.

The result is that the channelized Pocomoke transmits water more rapidly off the land and into the Bay, without giving that water an opportunity to spill into the full floodplain where nitrogen, phosphorous and sediment are filtered. Nitrogen, phosphorous and sediment are all major contributors to “dead zones” in the Bay, which can suffocate underwater life and shrink available habitat to fish, crabs, and other marine life.

The largest dead zone is most pronounced in the deep waters of the Bay’s mainstem during warm summer months. Between 1985 and 2010, the duration of the dead zone fell from five months to four, suggesting efforts to manage nutrient pollution are working. The 2016 dead zone was smaller than average because of low river flow and reduced springtime nutrient-rich runoff, and restoration efforts like the Pocomoke will help even more.


FREEING A TRAPPED RIVER

 

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Men walk along the Pocomoke River drainage project, July 1, 1943.  Photo by Wallace Kirkland/The LIFE Picture Collection/Getty Images

In 2017, partners came together to restore in initial 9-mile stretch of the channelized portion of the Pocomoke River while not impacting the needed drainage to residents upstream. The scale of the Pocomoke floodplain restoration project is massive – encompassing roughly 4,000 acres of floodplain along nine miles of the river. The restoration itself is focused on a narrow band of dirt (spoil banks), which were piled over 12 feet high in some areas along the river’s edge during the dredging operation.

The Pocomoke River Restoration Partnership includes the U.S. Fish and Wildlife Service (USFWS), the U.S. Department of Agriculture’s (USDA) Natural Resources Conservation Service (NRCS), the Maryland Department of Natural Resources (MD DNR), the U.S. Geological Survey (USGS), the France-Merrick Foundation, the National Fish and Wildlife Foundation (NFWF), and The Nature Conservancy. 

The partnership has led to one of the largest ecological restoration efforts in Maryland’s history, and each partner plays a critical role: The NRCS secured easements and financial incentives for interested landowners and engineering of restoration, USFWS provided technical expertise to design effective restoration techniques, MD DNR provided project support and financial investment. The USGS monitored water quality.

The Conservancy’s work to advance outreach, implementation and monitoring was supported through the generous support of our private donors including the France-Merrick Foundation and the Maryland Chesapeake and Coastal Bays Trust Fund. And NFWF has leveraged the great work of this project to support targeted restoration in other areas of the Chesapeake Bay.


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Heavy equipment was brought in to cut breaches into the spoil banks, reconnecting the river with its floodplain.  Photos © Matt Kane / The Nature Conservancy

The most complex and challenging element of the Pocomoke floodplain restoration, perhaps not surprisingly, is the human element. With the number of federal, state and local government decision-makers involved, the private landowners whose participation is critical to the effort were at risk of being overwhelmed with information.

The Nature Conservancy is investing the time to engage landowners to help them identify a restoration plan that works for them whether that is enrolling in a government program, placing an easement on their property, or entering into a private agreement with the Conservancy. As one landowner partner noted, “The Nature Conservancy has been great to work with. They keep me informed when they’re working on the property, which is especially important during hunting season when we have a lot of people hunting on the property.”

We find that people are always a critical component of the environmental conservation equation, and in the case of the Pocomoke floodplain restoration, people are working together toward a common interest so that we can all continue to reap the natural benefits of the Pocomoke River.

Mike Dryden, restoration specialist with the Conservancy, and our project partners have successfully engaged 24 landowners in the 9-mile stretch to be able to restore 75% of the floodplain area which was the key to the success of this project. “It’s really important to educate the community on this program, to make people feel comfortable about enrolling in the program. We want to let them know that they’re restoring the land so that future generations can enjoy it,” says Dryden. Mike continues to talk with the remaining landowners about future restoration. 

To restore the river, heavy construction equipment was brought in and operated by local contractors to carve breaches, some up to 100’ in length, through the spoil banks, reconnecting the river to its floodplain swamp. When the project is completed the number of breaches will exceed 100. Different methods of stabilizing the breaches from erosion are being tested, including the planting of native vegetation.

As the Conservancy and our restoration partners work to engage more landowners in the ongoing effort, there is one partner whose job is just getting started – nature itself will eventually take over.


GUIDED BY SCIENCE

 

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Conducting monitoring activities along the Pocomoke River.  Photos © Severn Smith / The Nature Conservancy

As a leading science organization, The Nature Conservancy is focused on conservation programs that we know will have a significant and lasting impact on the environment.

With over 600 scientists employed by the Conservancy, we are committed to solving problems that have profound implications for the quality of our lives and for all other life on the planet. The Pocomoke Floodplain Restoration is one of the many science-driven conservation projects that has been prioritized by the Conservancy.

In 1998, the U.S. Geological Survey (USGS) started studying the Pocomoke River to understand the effect that channelization was having on water quality for the Chesapeake Bay. Greg Noe, USGS Research Ecologist, explains those early studies when he states, “we set up a study with sites in the floodplain that were outside of the channel, which didn’t receive any floodwater, and sites that were downstream that hadn’t been channelized and still naturally functioned like a floodplain. What we found with those early studies is that channelization did make a big difference on water quality. The channelized floodplains trapped very little phosphorous, nitrogen and sediment, whereas the natural floodplain downstream of the channel trapped a lot of phosphorous, nitrogen and sediment.”

Today, The Nature Conservancy continues to collaborate with USGS and USDA scientists to further understand how floodplain function varies in relation to how near or far it is from the headwaters of the river and the health of the wetland. At six sites along the Pocomoke River, a network of monitoring equipment has been installed in strategic positions to evaluate restoration benefits: two monitoring devices are in sections of the river that remain channelized, three set along sections that have been restored, and one set within a naturally connected river channel.

The monitoring program will enable us to gather data on water level fluctuations and the impact the floodplain reconnection is having on flood reduction for downstream communities, and the data will enable us to track how long water remains in the floodplains and the impact of that natural storage and filtration process is having on water quality improvement for the Bay. And the initial monitoring results are exciting: “we’re now seeing from the monitoring that this floodplain reconnection project is providing the benefits that we anticipated,” states Erin McLaughlin, Restoration Ecologist with MD DNR.


LIFE IN A CYPRESS SWAMP

 

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Swamps and wetlands support a rich biodiversity of species.  Photo © Kent Mason

The cypress swamp forest and wetlands that are fed by the Pocomoke’s natural flooding patterns are a biodiversity hotspot. The floodplain swamp provides habitat for an incredibly diverse list of plant and animal species. The river itself, while altered, is home to numerous species of resident and migratory fish including herring and shad. And perhaps most notably, more than 60 recorded species of migratory songbirds use the Pocomoke watershed as a stopover area during annual migrations.

“Forested wetlands and mixed upland forests in the Pocomoke River watershed are identified as high priority habitats to the Federal government because they support high priority species, such as the wood thrush, Swainson’s warbler, Kentucky warbler, Louisiana waterthrush, worm-eating warbler, Acadian flycatcher, yellow-throated vireo, prothonotary warbler, red-headed woodpecker, barred owl, and great-blue heron.

High priority habitats are those that are either in need of critical conservation attention or are critical for long-term planning to conserve regionally important bird populations,” states Dan Murphy, Chief of the Division of Habitat Conservation for the U.S. Fish & Wildlife Service, Chesapeake Bay Region.

The wild and scenic Pocomoke River also drives a tourism industry that has become one of the largest economic sectors in Worcester and Wicomico counties. The state parks, state forests, wildlife management areas, and nature preserves bordering the 73-mile-long river offer recreational activities almost as varied as the species that inhabit the swampy floodplain.

Locals and tourists alike enjoy the hiking, camping, boating, fishing, birding, paddling, and picnicking opportunities provided by the river. The quaint towns and villages that dot the Pocomoke’s watershed offer shopping, dining, entertainment, and discovery for people of all ages. Restoring the river’s natural beauty, and preserving the watershed’s fragile and captivating ecosystem is in everyone’s best interest.


LOCAL TO GLOBAL

 

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Breaches in spoil banks reconnect the Pocomoke River to its floodplain swamp.  Photo © Matt Kane / The Nature Conservancy

We believe the Pocomoke floodplain restoration is replicable and scalable to other channelized rivers in the Chesapeake Bay watershed, and other sites across the country and around the world.

As a global organization, The Nature Conservancy has a network in place that allows us to share our monitoring data with other regions that can look to the Pocomoke restoration as a best practice. Dr. Boomer has recently made several trips to China to share our Pocomoke story, and help translate the science into a watershed management plan that will help address similar water resource concerns in China.

This local-to-global sharing is an exciting example of the Conservancy’s international science leadership, and reinforces the importance of international collaboration to address global environmental issues. “Despite all our cultural differences,” says Dr. Boomer, “Americans and Chinese face very similar challenges in advancing clean water goals.”

 

Download the Pocomoke Floodplain Restoration factsheet (pdf)

Hear from Conservancy staff and partners who are working to restore the Pocomoke river.

Categories: Clean Water, Wetland Restoration, Chesapeake Bay





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