Baltimore County's man-made wetlands may offer a line of defense against climate change
Editor's Note: This is part of WYPR’s ongoing coverage of Climate Change In Your Backyard.
Walking down to Bullneck Creek at Chesterwood Park in Dundalk, Baltimore County Environmental Protection and Sustainability Director David Lykens pointed out one of the county’s dozens of man-made wetlands. This one protects 450 feet of shoreline, about the length of one and a half football fields.
“Some of them are thousands of feet long,” Lykens said. “We have them all sizes, all styles throughout the county.”
For decades, Baltimore County has spent tens of millions to create marshes to fight erosion and pollution. Now that climate change is threatening shorelines, officials will be watching to see if that investment will offer protection or eventually be inundated by rising waters.
More than 4,200 tons of sand were trucked in and 8,000 wetland grasses were planted to create the Chesterwood Park marsh last spring at a cost of $708,000.
David Riter, the supervisor of the county’s waterway restoration program, said a barrier made of stones protects part of the marsh during storms.
“If we didn’t have a structure in front of the sand, it would wash into the water,” Riter said.
Over the last 30 years, the county has done more than 40 shoreline projects at a cost of around $21 million. During that time, they’ve seen an uptick in intense storms, according to Rob Ryan, the county’s watershed restoration manager.
“Related to like tropical storms and wind and wave energy along the shoreline which is creating more erosion along the tidal waterways of Baltimore County,” Ryan said.
Wetlands act like a giant sponge, absorbing water then releasing it slowly.
Rising sea levels caused by climate change were not part of the equation when environmentalists began building marshes in the 90s according to Alice Besterman, an assistant professor in the department of biological sciences at Towson University.
“That has much more clearly emerged as a stressor for coastal wetlands within the last 10, 15 years,” Besterman said.
Marshes could be threatened by rising sea levels according to Besterman, although she added coastal wetlands can survive because they naturally increase their elevation.
“However, there is a limit to the rate they can do that,” Besterman said. “So if sea level begins rising, or accelerating really, faster than the marsh can keep up, you do start to see effects.”
Besterman said the Baltimore Metro Area is not yet at the tipping point where marshes are threatened and there are ways they can be protected and restored.
Baltimore County’s Sustainability Director Lykens said they have to build shoreline projects based on today’s reality, not what might happen in the future.
“We’re not looking at what 2030 is going to be or what 2050 is going to be and what potential sea level rise we might see then, because if we build it for that they might be sitting up in the air today and they wouldn’t be effective today,” Lykens said. “So some of the projects we build today, when we get to 2030 or 2050 may be under water, but we have to try to do what we can for today’s standards.
It’s not like there is a great alternative according to Chris Overcash with EA Engineering, Science and Technology, Inc., PBC, a scientific consulting firm in Hunt Valley.
Overcash recently told the county’s commission on environmental quality that hard barriers like a seawall can disrupt the natural flow of sediment and waves which can then do damage to nearby unprotected shorelines.
“Placement of hard structures many times causes much more harm than good in the long term,” Overcash said.
Wetlands can do more to combat climate change than provide a coastal line of defense. Professor Besterman at Towson said they are also great at grabbing carbon from the atmosphere. She said marshes build up thick mats of organic matter that store a ton of carbon.
“That is unique to wetlands,” Besterman said. “If you contrast it with even forests or even tropical forests per acre, wetlands store more carbon and take up more carbon than those systems do.”
Baltimore County has more than 200 miles of shoreline. Where the county decides to build wetland protection depends on where it’s most needed, who owns the land and the money available.
The program is driven by federal and state regulations, requiring localities to reduce levels of sediment, phosphorus and nitrogen that end up in the Chesapeake Bay by traveling through its tributaries.
Not far from the Chesterwood Park wetland project is another much larger man-made marsh at Inverness Park on Bear Creek.
“I’m really proud of this one,” said David Riter, the county’s waterway restoration program supervisor.
The $1.3 million project created 1.2 acres of marsh. Riter said it has stabilized erosion and they are seeing more aquatic vegetation near the shore.
The wetland was completed in 2018 and Riter said they continue to care for it.
“Living shorelines are kind of like a garden,” Riter said. “You need to tend it. You can’t just plant it and walk away and expect it to be successful.”