Carp Barrier

Silver and Bighead Carp are exotic invasive fish stocked originally in farm ponds. After escapes and  accidental releases into streams, these fast-growing, prolific  breeders have made their way up the Mississippi River and into the Illinois River drainage, devastating biotic communities. As they  advance towards the Great Lakes, they threaten a multi-billion-dollar fishery.


Various strategies have been implemented to prevent their spread, including bubble nets and electric aquatic “fences.” During high water events, the Des Plaines River can overflow into the Chicago Sanitary and Ship Canal, providing a potential unprotected pathway for Carp to reach Lake Michigan.

Common Snapping Turtle along carp barricade


In 2010 a 13-mile concrete and steel mesh wall was put in place to keep the Des Plaines River and the Chicago Sanitary and Ship Canal separate during flood events.

The barrier keeps carp out but may also restrict animal movement (especially reptiles and amphibians) between the Des Plaines River and adjacent wetlands.



Twenty gates were installed in the barrier to allow animal movement, specifically the state endangered Blanding’s Turtle, and are closed during flood events.



What we’ve done:

– We attached cameras to the back of 14 gates to see what animals use the gates.

– We conducted visual surveys for reptiles and amphibians along the Carp Barrier.


What we’ve found:

      •  We documented 10 reptile and 5 amphibian species during visual surveys along the Carp Barrier, including 3 Blanding’s Turtles.
      • We documented 9 reptile and 2 amphibian species using gates in the Carp Barrier with trail cameras, including Blanding’s Turtles 12 times.
      • Although the gates  effectively facilitated animal movements, the barrier increased predation and mortality risks.
      • We found many depredated nests (54) along the trail and barrier
      • We found evidence of mortality from cycling and mowing.
      • Reptiles, especially snakes, were more at risk to bicycle traffic and mowing than predation.
      • We recommended mowing be avoided in late May – June when snake and turtle activity are highest.
      • We also recommended the construction of 3 additional gates between the northeastern most gate and the I-355 Bridge, where numerous turtles were found along the barrier.
Trailcam attached to gate in carp barrier

Other Amphibian and Reptile research


Ross, J. P., and M. J. Dreslik. 2020. Camera trap monitoring of turtle passage gates along the Des Plaines River carp barrier.  Illinois Natural History Survey Technical Report. 2020(3):1–45.

Ross, J. P., C. Y. Feng, J. K. Warner, and M. J. Dreslik. 2017. Turtle monitoring at the Interstate 355 Des Plaines River bridge  crossing and the Centennial Trail Asian carp barrier. Illinois Natural History Survey Technical Report 2017(15):1–45.