Rooting for our Waterways - Delaware Nature Society

The plants and trees that grow along our streams and rivers keep them healthy. Though often degraded, there are ways to restore these important riparian buffers.

By Ken Mammarella

Since 1991, Delaware Nature Society has planted more than 55,000 trees and shrubs along the stream and in the former farm fields that drain into it at Middle Run Valley Natural Area, a New Castle County park near Newark.

The result is a widening riparian buffer, the technical term for the trees, shrubs, and other plants that grow along a waterway. Riparian buffers provide many essential benefits to Middle Run Creek and other waterways where they grow naturally and where they are re-created or enhanced to compensate for prior loss or damage.

“It’s relatively easy to plant,” says Kristen Travers, the society’s director of conservation. “The challenge is maintaining it.”

Buffers provide habitat for wildlife, offering food and cover. Tree canopies give shade that moderates temperatures on land and in the water. They improve water quality by filtering out pollutants and capturing sediment that would otherwise wash into the water. And they reduce flooding by soaking up stormwater, stabilize banks with their root systems, and enhance the value of nearby properties.

“They also add to our quality of life through aesthetic amenity and the peace of mind that a person has knowing of and experiencing the healthy stream and riparian ecosystem that the buffer provides,” according to the Delaware Riverkeeper Network. “There may be no precise way to monetarily measure the value of quietly sitting under a tree or fishing in a creek, but these benefits are very real nonetheless.”

Yet there is a real threat to our remaining buffers.

“We have degraded these streams and their watersheds for 300 years,” says Lamonte Garber, watershed restoration coordinator at the Stroud Water Research Center in Avondale, Pennsylvania. Clear-cutting, agriculture, and industrialization by European colonists and their descendants have all take their toll. “We can’t expect them to recover overnight.”

Organizations like Stroud and Delaware Nature Society can help.

The Benefits of Buffers

“If the stream could talk, it would say, ‘I want 100 percent forest and working wetlands in my watershed,’” Garber says. “We know that’s not realistic.”

Instead, one of Stroud Center’s critical roles is to help farmers across the region and enlist them in efforts to restore riparian buffers. One of many strategies farmers can employ to protect water quality, the Stroud Center team says, is to always balance resource protection and the farm’s need for productive acreage.

“Conservation practices that we will develop and implement with the farmer together can help restore some of the healthier functioning and cleaner water of the stream so that we can recover some of the natural function that we all want,” Garber says. “The farmer would love to have a cleaner stream where his or her kids and grandkids can play. But they also don’t want to give up the whole farm to a forest.”

The biggest benefit of a buffer is in managing temperature, Garber says. “Our streams are just too hot. To get enough of the shading, cooling environment that the stream needs, we need at least two or three rows of trees. And we need trees that will get enormous, like sycamores.”

Bottom line for the buffers that Stroud promotes: a minimum of 35 feet wide on each side of the waterway—though 100 feet is preferred.

“The wider the buffers, the higher the benefits,” Travers says. “Even though they look insignificant, they are the arteries of the larger system. You can see the influence of the trees as you walk through in July or August. You can see the trees at work.” The temperatures of both the air and water are lower. Even a few feet of unmowed suburban lawn provides some benefit to the waterway.

The watershed restoration team of the Stroud Center will help design, plant, and maintain the buffers, as the Delaware Nature Society’s conservation team does at Middle Run. Theoretically, the plantings could produce berries and nuts, “but that’s not a realistic addition to farmers who specialize in other products,” Garber says. “They want results and low impact on their operation.”

How Buffers are Reborn

Based on the Pennsylvania stretch of Wild and Scenic White Clay Creek, one of northern Delaware’s most important waterways, Stroud Center is a world leader in understanding the ecology and hydrology of stream systems, large rivers, and other waterways. It has developed a standard repair plan for riparian buffers: fence off the stream from cattle to prevent damaging quantities of manure and urine from entering the stream, then add plants.

“We plant 200 stems per acre, a mix of big trees, small trees, and shrubs,” Garber says. “That works out to be a tree every 15 feet. We’re planting them in rows–not that we want it to look like a cemetery–but for the first four years of the buffer, the most important person on the planet is the person on the riding mower.”

Mowing keeps the buffer from becoming a meadow filled with voles, which can kill young trees by chewing their bark or roots. The trees are also planted with shelters to protect them from browsing deer. Mowing also helps control invasive plant species.

“It’s not very successful just to let Mother Nature decide what will grow on the site because in this region, invasives predominate,” Garber says. “Mother Nature ultimately is going to have her way, but that won’t be a successful formula for people interested in having their properties look nice as well as being a conservation win. So we mow to keep the vole habitat down. Buffers that are neglected can have a mortality rate of 90 percent or higher, so within five years of planting the buffer it becomes one giant weed patch. That’s a billboard of failure in farm country.”

Stroud Center’s watershed restoration team uses environmentally and aesthetically successful buffers–which take at least a decade to establish–and work to convince nearby farmers to join the movement.

Stroud learned firsthand about these practices starting around 1990 when it tackled a stream near its research center. After the dairy cattle were moved off, multiflora rose invaded. Machete-wielding staff removed the rose, then planted native plants and sapling trees. Deer ate almost all of them. A second planting of trees with tree shelters around their trunks finally did the trick.

Buffers and Bureaucracy

As the frequency of large storms increases, and as more land is lost to development, flooding increases, making those buffers ever more important.

In the Chesapeake Bay watershed, which covers about a third of Delaware, there is a goal to restore 900 miles of riparian forest buffers per year and to conserve existing buffers until at least 70 percent of the riparian areas are forested across all watershed states.

That goal is not being met in Delaware, according to the state’s Department of Natural Resources and Environmental Control. Applying for help and subsidies through the U.S. Department of Agriculture’s Conservation Reserve Enhancement Program is cumbersome, its funding has been inconsistent, and it is often unattractive to farmers, who own land in much of the watershed. The report also notes trees in buffer zones make it difficult to maintain tax ditches, which are engineered to manage stormwater water on some farms and other areas.

Meanwhile, Sussex County spent three years studying its rules on buffers. In 2022, it adopted a new ordinance to protect them, “the most significant update to the county’s environmental protection laws in more than 30 years,” according to the county.

It doubles, from 50 feet to 100 feet, the size of buffering along and around new residential communities on tidal wetlands and waterways. It adds a 30-foot buffer requirement–up from none–for new developments along non-tidal wetlands and intermittent streams.

It is a step forward, though not as big a step as conservation advocates had hoped for. In the Maryland portion of the Chesapeake Watershed, the minimum is 1,000 feet—and there’s a clear difference in water quality.

About the Author: Ken Mammarella is a Delaware native and longtime journalist who in his spare time likes to explore the terrain by bike.