Calico Island: Calico Chute
Monroe County, Illinois
“On the right side of the river. The bank of the river from Little Plateen to this place has a majestic appearance. It is a continued rock of limestone rising from the base, declining step by step to the height of 2 or 300 feet; the steps or ledges not more than 6 inches deep, and appear as if cut by the chisel; and here and there springing forth are small cedars.”–Zadok Cramer, 1814
At Calico Island the Mississippi threads it way between the tall bluff on the Missouri bank and Calico Island in the Illinois bank.
Channel training devices, wingdams, diverted the rivers erosive power from the side channels to the navigation channels, where they scoured a navigation channel south of Alton. Closing dams across side channels, installed to prevent the river from adopting a side channel as its main channel. Sediment washing off the floodplain silted in the side channels, damaging habitat for fish and migrating waterfowl. What where once islands became part of the mainland. At the beginning of the twenty-first century only twenty-three side channels remained in the Middle Mississippi between Alton and the Ohio River, and they were severely degraded.
In 1994 a group of biologists from the U.S. Fish and Wildlife Service, the Illinois Department of Natural Resources, the Missouri Department of Conservation, and engineers from the Applied River Engineering Center at the St. Louis District of the Corps of Engineers formed a collation to restore riverine habitat to side channels of the Mississippi, while at the same time maintaining a reliable navigation channel. The collaborators build a table-sized model on which they could test their ideas for restoring habitat to Calico Chute and others in the Middle Mississippi.
When engineers and biologists examined Calico Chute, they found it in pretty good shape. Its width varied between 125 and 250 feet with an average of 200 feet. When the river ran low, its average depth of the channel was about nine feet, but there were places where it was a deep as twenty-one feet and places where it was almost dry, leaving its sandy bottom exposed. Old, broken wooden pile dikes marked the head and the foot of the chute. While Calico Island, 250 acres, on its right bank was heavily forested, farmers had stripped the 500 acres of floodplain on its left bank of trees for farm fields.
Little needed to be done to restore the diversity of its depth. Engineers inserted hard points constructed of rock, wood, or both at high energy areas along the chute to create deep scour holes for fish. They dredged where they didn’t want sand and added sand where they did, enlarging the sand bar at the foot of the island. Using sand dredged from the channel, they created ridges on the banks and anchored them with trees. Wherever possible they allowed water to flow through the chute and create a ridge and swale landscape. Finally, to reduce the amount of silt washing off the adjacent fields and into the chute, they would if they could reforest the denuded left bank with a riparian buffer of trees and shrubs at least a hundred feet deep.[i]
When the Corps of Engineers returned to Calico Chute after the passage of the Navigation and Ecosystem Sustainability Program in 2007, researchers found that Calico Chute lost connectivity to the main channel at low water. They predicted that the chute would be lost by 2050 if no work were done to open up the side channel.
That’s the bad news. The good news is the U.S. Fish and Wildlife Service would like to include Calico Island in the Middle Mississippi NWR, should be funds to purchase the land from twenty-two willing sellers ever become available.
[i] Cramer, Zadok, The Navigator, Ann Arbor: University Microfilms, Inc. 1966, 168; U.S. Fish and Wildlife Service, and the U.S. Army Corps of Engineers, St. Louis District, “Middle Mississippi River Side Channels: A Habitat Rehabilitation and Conservation Initiative, No Date, 17.