By Ken Mammarella
The before photos of the unnamed stream in a suburban subdivision show a waterway choked by vegetation, steeply eroded banks, and leafless trees—a mess for people, water, and wildlife.
The after photos show a miraculous transformation. There are low rock walls, a walking path, gently sloped banks, and two pedestrian bridges that connect the surrounding communities.
The project, in Robscott Manor on the southern edge of Newark, is a shining example of successful stream restoration, where planners and engineers turned a severely eroded tributary of the Christina River into a naturally functioning stream with a connected floodplain.
The benefits of the project are many. The water quality of nearby Christina Creek will improve as less sediment flows downstream, and the regraded floodplain will decrease flooding during heavy rains while increasing the removal of pollutants.
Federal rules require managers of municipal separate storm sewer systems to prioritize improvement of impaired watersheds. “The Christina rose to the top of our list,” says Mike Harris, New Castle County’s stormwater and environmental programs manager. Experts at the county and the Delaware Department of Transportation, which led this project, concluded that stream restoration was the best way to enhance both water quality and the landscape, Harris says.
The $3 million Robscott project covered 1,650 feet of the stream. In all Delaware, has 4,542 miles of waterways. Their issues vary, and so do their restoration efforts. Stream restoration projects in the pipeline for the county and DelDOT include Little Mill Creek and its tributaries in Woodland Run Park, northeast of Prices Corner, and Dragon Run, near Lums Pond.
Think Holistically
“Stream restoration is not one size fits all,’” says Kristen Travers, director of conservation for the Delaware Nature Society, adding that it can be expensive to restore waterways to peak ecological function. “Streams are dynamic systems, so when we encounter problems, we also need to think about what’s happening upstream,” Travers says. “Why does this problem exist in the first place?”
She ticks off a list of issues that lead to too much water flowing too fast, starting with too much development that results in too much land covered by impervious surfaces such as roadways, parking lots, buildings, and compacted soils. All those hard surfaces force rainwater to rush downhill instead of trickling slowly into the ground. The heavier the rain, the greater the impact. “That leads to severe erosion,” Travers says. “It damages the habitat within the stream and along the stream bank, and it results in flooding.”
To improve the situation, Travers recommends zoning changes that “protects stream-side areas and allows for buffer areas. “Are steep slopes being protected? Are wetlands being protected? Do we have good floodplain protection in place? Do we promote green stormwater solutions designed to keep the water on site as much as possible?
“We want to encourage good practices within our watershed,” she says. “Do we have good zoning? Are we protecting critical land, things like floodplains and wetlands? So it’s looking at the whole suite of different options and stream restoration is one of them.”
Next Up: Little Mill Creek
Little Mill Creek has been cutting deeper into the surrounding ground for decades, creating switchback bends and other features that worsen flooding. The county’s project will restore 8,500 linear feet of the creek, its tributaries, and outfall channels.
“We just be restoring the grade of the stream to what it should naturally look like, then creating areas for the stream to go out of its banks into wide floodplain areas during storm events,” Harris says. Water in the floodplain should percolate through the soil to recharge groundwater. The floodplain also slows the velocity of the stream to minimize erosion and sedimentation downstream.
The natural meandering of the creek will also be restored and the channel will be changed from a V-shape to a U to slow water flow, says Jason Zern a senior manager for New Castle County. The stream bed will be raised, allowing fish to migrate upstream of the Faulkland Road bridge, and boulders will be strategically placed to create pools for fish and other aquatic life. The project also includes creating five acres of wetlands, reducing invasive plants, and increasing native plants, which are naturally adapted to local growing conditions and the food and habitat needs of local wildlife.
That’s win for all.
About the Author: Ken Mammarella is a Delaware native and longtime journalist who in his spare time likes to explore the terrain by bike.
Learn more
Woodland Run stream restoration https://www.newcastlede.gov/2738/Woodland-Run-Stream-Restoration
Robscott Manor improvement project https://www.newcastlede.gov/2753/Robscott-Manor-Improvement-Project