With more than 150,000 miles of riparian forest buffers growing in the Chesapeake Bay watershed, it’s clear that planting trees and shrubs along rivers and streams is a popular practice for protecting waterways. While it stands to reason that wide forest buffers could generate more benefits than narrow ones, it was not until 2014 that the Stroud Water Research Center set about to determine just how wide a buffer needed to be to work.
When Stroud Water Research Center President, Director and Senior Research Scientist Bernard W. Sweeney and Research Scientist J. Denis Newbold dove into research on forest buffer width, they were already decades into forest buffer history. In the seventies, wide zones of streamside vegetation were known to protect streams from the impacts of logging. In 1985, the sixth U.S. Farm Bill funded the planting of streamside vegetation to slow farmland erosion. And seven years later, research from Sweeney himself revealed the quality of streamside vegetation was likely the single most important human-altered factor affecting the structure, function and quality of our streams. But would width amplify all the benefits a forest buffer has to offer? And how wide is wide enough?
After examining eight ecosystem functions streams are known to support—including nutrient removal, sediment trapping and the health of macroinvertebrates and fish—Sweeney and Newbold found that the integrity of small streams can only be protected by forest buffers at least 30 meters—about 100 feet—wide. In other words, the ideal width of a forest buffer is only slightly shorter than three school buses laid end to end!
Of course, Sweeney and Newbold recognized the layout of a particular piece of land could limit the width of any forest buffers that may be planted there. The scientists also acknowledged forest buffer policies may need to accommodate site-specific factors. In the Chesapeake Bay watershed, a forest buffer must be at least 35 feet wide to count as a pollution-reducing practice that supports work toward the Bay’s “pollution diet.” Even so, the average forest buffer in the watershed is almost three times this size, and the benefits of a wide forest buffer are clear.
According to Sweeney and Newbold’s literature review, which synthesized the results of hundreds of scientific studies, effective nitrogen removal requires buffers that are at least 30 meters wide. Buffers of this size can also be expected to trap about 85 percent of any sediment delivered by water moving over the land (which is 30 percent more than a buffer only 10 meters wide!). A 30-meter width can also ensure a buffer protects streams from measurable increases in water temperature during summer months; sends a natural level of stems, branches and other large woody debris into a waterway; and supports natural macroinvertebrate and fish communities.
In our watershed, the planting and care of forest buffers can be limited by a lack of technical assistance and maintenance support. Indeed, buffer restoration has slowed in recent years. While the Chesapeake Bay Program has set a goal to restore 900 miles of buffers every year until at least 70 percent of the watershed’s riparian areas are forested, plantings continue to fall short of this annual target: last year saw the lowest restoration total of the last 16 years.
As part of our work to restore forest buffers, our partners have committed to increasing efforts to teach landowners about buffer establishment and care. Our partners have also committed to better tracking and spending technical assistance funds, seeking out additional funding for the suppression of interfering weeds and determining whether current payments that support buffer care should be raised.
Learn about our work to restore forest buffers.
A new report from the U.S. Geological Survey (USGS) explores variations in water quality in four small watersheds in Maryland, Pennsylvania and Virginia. Results of the study will aid in efforts to understand how pollution-reducing practices affect the health of waterways in these areas.
When agricultural best management practices—or BMPs—like cover crops and streamside fencing are implemented, the water quality improvements that may result are more likely to first be detected at a smaller scale. But although water quality throughout the Chesapeake Bay watershed is monitored through a large-scale network, fewer resources exist for monitoring smaller watersheds.
In 2010, the USGS partnered with the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Agriculture (USDA) to monitor water quality in four small (i.e., less than 150 square miles) watersheds: Smith Creek in the Shenandoah Valley of Virginia; the Upper Chester River on Maryland’s Eastern Shore; Conewago Creek near York, Pennsylvania; and Difficult Run near Great Falls Park in Virginia. Representing a wide range of land uses and geologic features, these four regions had been targeted as “showcase projects” for the increased use of BMPs as part of the Chesapeake Bay Executive Order Strategy.
From 2010 through 2013, experts monitored water quality in the four areas, measuring aspects of water chemistry—such as dissolved oxygen, temperature and pH—as well as nutrient and sediment pollution. The results, available in the report, will allow scientists to characterize current conditions, identify sources and sinks of pollution and understand the movement of pollutants like nutrients and sediment in each watershed. Future work building off of these results may improve knowledge of how water quality in these areas responds to BMPs, allowing for the focused implementation of practices to reduce nutrient and sediment pollution.
The Elizabeth River Project stored roughly 1,000 cubic yards, or about 30 truckloads, of shucked oyster shell in Chesapeake, Virginia. Now, these shells are part of a 1-acre oyster reef located in the Eastern Branch of the Elizabeth River, in a project funded by the National Fish & Wildlife Foundation.
The Eastern Branch oyster reef was constructed in two layers. On the bottom is a layer of crushed concrete, recycled from nearby buildings that were knocked down, followed by a layer of shells sourced from shucking houses in North Carolina. The Elizabeth River Project completed building its acre-sized oyster reef in June, but has a much larger goal of restoring 10 acres of native oysters by the year 2024. Using a National Oceanic & Atmospheric Association survey of the Eastern Branch, the Elizabeth River Project identified an additional eight acres for restoration and is now working on getting funding to continue their restoration work.
Along with creating the oyster reef, the Elizabeth River Project has also been busy building oyster “castles” along the branch’s shoreline. Oyster castles are stacks of concrete blocks that create suitable habitat for first-generation oysters. The height allows for oysters to attach without sinking into the mud, and since oysters prefer to attach to areas that already have oyster shells, the blocks typically contain about 30 percent shell.
The restoration projects in the Eastern Branch would not be possible without local partnerships, says Deputy Director of Restoration Joe Rieger. The Elizabeth River Project partnered with organizations such as Kinder Morgen to store and stockpile oyster shells, the Hampton Roads Sanitation District to turn waste concrete into oyster blocks and the Chesapeake Bay Foundation to eventually seed the area with baby oysters.
Image by Will Parson
Oysters are simple creatures; they have no centralized nervous system and take in nutrients passively through water filtration. Their impacts on the Chesapeake Bay, however, are multi-faceted and far-reaching. They have cultural, economic and biological significance that goes far beyond their humble station as filter-feeders. The Edgewater, Maryland-based South River Federation and John Flood, one of its founders, understand that restoring the Chesapeake Bay and its tributary, the South River, means oysters need to have a fighting chance and some good real estate.
Throughout an oyster’s lifetime—which ranges from several years to twenty years in captivity—it will filter about 50 gallons of water a day, every day. If one oyster lived for four years, it could filter 73 thousand gallons of water, effectively removing contaminants and algae in its pursuit of nutrients. Multiply that by the thousands of oysters on a sanctuary reef and you’ve got some serious and sustainable filtration power to clean up the Chesapeake Bay and its tidal rivers.
One of the hurdles facing oyster restoration in the Chesapeake Bay is how vulnerable the oysters are in their first year of life. If the baby oysters, or spat, are simply dumped into the water and left they can contract disease, become food or succumb to nutrient pollution. To combat this, John Flood began growing oysters in repurposed paint buckets. The buckets hang suspended in the water off of docks for their first year, then Flood and volunteers load up his small fishing boat or the Federation’s Carolina Skiff with adolescent oysters and takes them to a sanctuary reef where harvesting is prohibited.
These “Flood buckets” don’t need much until they are ready to be transferred to a sanctuary reef. Growers need to make sure the oysters remain submerged but off the bottom and clean them off every couple of weeks to prevent too much algae from collecting on the cages and restricting circulation. At the end of the year, they take their briny charges to join a sanctuary reef where they will hopefully live out their lives performing their simple function of siphoning nutrients from the current.
On September 23, 2016, volunteers from Price Waterhouse Cooper went through the labor intensive, muddy but important work of emptying the almost 200 buckets hanging from a private marina dock in Flood’s waterfront Annapolis neighborhood. Busy dislodging oysters from their first homes with a combination of sledge hammers and vigorous shaking, they were careful to allow the fish, eels and crabs that made their home in the buckets to evacuate. Once free, the oysters were ferried to their new homes on the South River sanctuary reef.
Flood is the “godfather of citizens growing oysters,” according to Nancy Merrill, Volunteer and Outreach Program Coordinator for the South River Federation. He’s also a salty guy with a lot of intensity. Concerned about poaching on the sanctuary reefs, Flood and Merrill don’t like to share the exact location. “If we showed it to you we’d have to kill you,” Flood joked with volunteers.
Flood felt a great sense of loss when he saw the dismal state of the South River: dead underwater grass beds, chemical contamination and major oyster reef degradation. This was the river he spent his childhood fishing and swimming in, and that long-standing connection called him to action. “I watched it collapse from nutrient pollution when I was a boy,” he said, adding later, “I lost something that was too valuable not to fight to get it back.” By helping to found the South River Federation in 2000, he hopes to aid in bringing back underwater grass beds and oysters, thereby improving the river and the Chesapeake Bay for future generations.
There are close to 70 oyster growers working directly with the South River Federation, who partners with Maryland Department of Natural Resource’s Marylanders Grow Oysters Program. Through the state’s program that works with local groups, 1,500 waterfront property owners on 30 Bay tributaries are growing millions of young oysters for sanctuary reefs.
“The lonely oyster, to me, is the symbol of recovery,” Flood said. “And if we would let it work, respect its simple function in the Bay, harvest it sustainably and realize its importance as a keystone species then we can understand the Bay better and be better stewards.”
Text, images and captions by Leslie Boorhem-Stephenson