How Snow's Cut Changed the Cape Fear River
Text and Photos by T. Travis Brown

When a local fisherman looking for a short-cut to the sea blasted open Carolina Beach Inlet in 1952, he had no idea about the ecological impact this would have on the Cape Fear River.

Have you ever wondered what caused all of those trees to die along the Cape Fear River? You see them in the creeks that you cross on River Road—lonely bleached out remains of once gnarly, but majestic, cypress trees. It seems odd that a tree would have ever grown out in the middle of a salt marsh. Well, they didn’t, because these areas weren’t always salt marshes. Not too long ago they were shady cypress swamps. What events could have changed the nature of the Cape Fear so drastically as to turn cypress swamps into salt marsh? Snow’s Cut and Carolina Beach Inlet.

MAN-MADE CHANGES
Snow’s Cut was excavated between 1929 and 1934 as part of the Intracoastal Waterway (ICWW). It connects the Cape Fear River to Myrtle Grove Sound. Carolina Beach Inlet was opened in 1952 by fisherman looking for easier access to the sea.

Today, any projects as extensive as these would be the subject of extremely thorough environmental reviews. There would be volumes written that describe how water flow patterns, salinity, invertebrate communities, wildlife use, etc. would change as a result. However, no such process existed in those days.

In fact, according to Dr. Orrin H. Pilkey (Duke University) et al.’s The North Carolina Shore and Its Barrier Islands, Carolina Beach Inlet was opened illegallydespite warnings from engineers that it would cause increased shoreline erosion.

These two waterways create an entrance to and from the ocean 10 miles upstream from the mouth of the Cape Fear River. Consequently, saltwater is intruding further upstream than was the case in the past. The dead cypress trees are undeniable evidence of how saltwater intrusion changed the river’s ecosystem. Cypress swamps, which would have looked similar to Greenfield Lake, are transitioning to salt marshes. In place of the cypress, plants like smooth cordgrass and black needlerush grow, and environments typical of the lower Cape Fear begin to creep upstream.

“Saltwater intrusion is one of the most significant issues facing the Cape Fear watershed,” said Joe Abbate of Cape Fear River Watch. “Cypress trees are a great indicator of a river’s salinity [the smallest change can kill them] and we’re seeing Cypress trees dying up to 10 miles north of the Port of Wilmington.”

Of course, bald cypress is not the only species affected by saltwater intrusion. There are hundreds of other freshwater marsh plants that cannot tolerate high salinity. Similarly, freshwater fish cannot handle saltwater intrusion. For example, Currituck Sound (up north in Currituck County, bordering Virginia) was once a famous destination for largemouth bass fishing, but saltwater intrusion from a yet-unidentified source has virtually erased it from the bass fisherman’s map. Amphibians, who breathe (at least partially) through their moist skin, cannot handle the drying effects of salt. Many invertebrate species, such as oysters, also have very specific salinity requirements. Also, there are many terrestrial species, such as birds and mammals (including humans), which depend on fresh water for their livelihood.

In all fairness to Snow’s Cut, it is difficult to pin down one cause of saltwater intrusion into the Cape Fear watershed. For one thing, deepening of the river to accommodate a shipping channel to Wilmington’s Port allows more saltwater to backflow into the Cape Fear at high tide.

“The deep channel definitely affects the river’s salinity, and may eventually have an effect as far upstream as the first Lock & Dam,” said Abbate. “People are already finding blue crabs on the Northeast Cape Fear 10 miles above Wilmington. We need to watch this closely, because Wilmington gets its drinking water directly from the Cape Fear River.”

In addition to dredging of the main channel, many side streams have been “channelized” (dug out into straight drainage ditches) in order to drain land for agriculture and forestry. (See article on page 18 for an in depth analysis of erosion at Snow’s Cut Park.)
Sediment is bad news because it fouls fish gills, covers aquatic animal eggs, clogs up filter-feeders like shellfish, and reduces light available for submerged vegetation (which is an important fish habitat) to grow. Not to mention the fact that sediment fills in shipping channels which must then be dredged, causing additional cost and disturbance.

A DIVERSE BODY OF WATER

Having the largest watershed of any river system in North Carolina, it’s no wonder that the Cape Fear is important. However, its ecological value is related to much more than its size.

For instance, the northern-most reaches of many plant and animal ranges is very close to this area. Most American alligators are found from Wilmington southward (although stragglers make it as far as southern Virginia). Also, the possibly-extinct ivory-billed woodpecker was once found at the northern extent of its range in the swamps of the Castle Hayne area.

The Cape Fear is home to both freshwater and saltwater species now. The upper portion of the river is home to freshwater species such as largemouth bass, catfish, and freshwater swamp plants such as bald cypress. As you move downstream the river becomes more brackish (meaning a mix of fresh and salt water) in nature and some of those freshwater species give way to species that prefer estuaries, such as flounder, red drum, and salt marsh plants such as smooth cordgrass. This mix of freshwater and estuarine species makes the Cape Fear River a highly diverse system as a whole.

One of the most important ecological functions of the Cape Fear River is as a nursery area for juvenile marine species. Animals, including blue crabs, spot, Atlantic croaker, pinfish, Atlantic menhaden, bay anchovies, and others, use the Cape Fear and its tributaries as a nursery. Larvae of these species swim or drift up into the shallow, vegetation-laden waters where they benefit from abundant food and a reprieve from marine predators. Without the Cape Fear River, North Carolina’s fisheries would not be what they are today.

The Cape Fear does all of this in spite of the alterations that have affected it for over a century. In fact, it is difficult to picture what the river must have been like as a natural system.

“It’s just such a highly altered system, so it’s hard to know what the lower Cape Fear was like before people began changing it more than a century ago,” says Mike Mallin, UNCW professor of Estuarine Ecology.

In a way, we jeopardized an environment that we depend on in order to build Snow’s Cut and Carolina Beach Inlet. We accepted ecological costs because of our desire to ship supplies to homes and industries.

Those relic cypress trees you see along River Road are a reminder of some of the choices humans have made in the past. Standing like weathered sentinels, these lonely skeletons are the ghosts of a river ecosystem that began changing over 60 years ago.

November 2008