If you live in central or southwest Indiana, you most likely have your own story to tell about the flood of 2008—the worst flood in Indiana’s modern history. Indiana’s Wabash River has its own story as well. The river’s most recent revision began during the flood and it’s a chapter that is still being written in Posey County.
For years, Mackey Bend had been partially surrounded by a six-mile loop of the lower Wabash River. Then the force of flood waters inundated the river’s banks and cut a new channel across a narrow strip of land of the bend making the land accessible only by boat—now known as Mackey Island. This evolutionary chapter in the river’s history continues to transform land and water resources and will for years to come.
The agricultural fields that used to be tended at Mackey Bend are inaccessible to agricultural equipment now and have been abandoned since the formation of the 1,700-acre Mackey Island. Eventually, silt and organic debris will cut off the old channel.
This process could take several years. The old channel will close off completely and the Wabash River will be six miles shorter. Yet the Wabash remains the longest stretch of undammed river east of the Mississippi River. Also, a huge oxbow lake will be left behind. The new, six-mile-long lake will be fed by rainwater runoff, river water that seeps through the very porous soils and waters that overflow the Wabash River banks during floods.
In late spring of 2009, another island was created just east of the first island at Mackey Bend, when the Wabash River again flooded and cut another new channel. The smaller island is about 300 acres in size. It is anticipated that this process may happen again, creating a maze of small islands and slack waters that provide important spawning habitat for a variety of threatened fish species. The area likewise will provide important sheltering habitat for migratory birds, including waterfowl.
Because so many of our eastern rivers in the United States have been altered—by dams, locks, flood control barriers, and straightened for transportation purposes—oxbow lakes, an entirely natural phenomenon, are unusual and highly important habitat for a variety of animal and plant species—both aquatic and terrestrial.
Valuable chance to observe adaptation
The Mackey Islands created in this fashion will provide a unique opportunity for the study of how plants and animals adapt to these changes. These oxbow lakes provide critical habitats for some of our most imperiled fish in the Wabash, such as the paddlefish and the slough darter.
Perhaps just as interesting, these oxbows may allow two deep southern species to re-colonize Indiana waters: both the alligator gar and the alligator snapping turtle once occurred in the backwaters of the lower Wabash, and could well return to the habitats that are being created in the Mackey Islands oxbow lakes.
The southern portion of the river and its tributaries provide habitat for some of the northernmost examples of what are essentially southern plants and animals, such as cypress sloughs and the Swamp rabbit. As our climate changes, we anticipate that protecting species at the northern-most extent of their range will give those species a better chance of surviving dramatic, quick (on a geological scale) changes in climate and to move even further northward if necessary.
Keeping it natural—protecting the processes in place
Imagine, we have the opportunity to make it possible for southern species such as the alligator snapping turtle to return to this environment on their own, or if needed, we can garner resources and partner to reintroduce them to Indiana. In terms of climate change, this spot on the map could be very important for the movement of animals, both aquatic animals, and waterfowl.
Our main concern is the fate of the oxbow lakes. By securing the lands that form the Mackey Islands, we can assure that the natural processes that will maintain the habitat values of the oxbow lakes can be secured for the future. In addition, we can assure that the adjacent lands provide suitable habitat for species that depend on the river for food and water but take shelter amongst the trees and plant life that border the lake.
We would like to acquire 1,000 acres, which will allow us to help shape the management of the oxbow lakes into the future. Fortunately, this site is of sufficient scale that all the needed ecological processes are still in place, with overall size and seasonal flooding being the foremost of these.
Progress is being made
The owners of the farmland on these two islands have enrolled their properties in the federal Floodplain Easement program (in most cases) and in the federal Wetland Reserve Program (in two cases), which provide permanent conservation protection for the land. Under these programs, the lands will be allowed to revert to natural vegetation and thus will be well-suited to the periodic flooding that occurs, principally in the spring. Approximately 40 percent of the islands were already covered in small wooded areas and sloughs created by river bank erosion, which are serving as the seed source for other trees and understory plants as the land reverts to a natural state.
To date, the Indiana Chapter has acquired two tracts of land on these islands, covering almost 251 acres, or a quarter of our initial goal.