The Chicago Area Waterway System (CAWS) is the only known continuous connection between the Great Lakes and Mississippi River basins and poses the greatest potential risk for the transfer of aquatic nuisance species.
The Electric Dispersal Barriers are located near Romeoville, IL in the Chicago Sanitary and Ship Canal (CSSC) within the CAWS. The CSSC is a man-made hydrologic connection between the Great Lakes and Mississippi River basins that was completed in the early 20th century to address sanitation and flooding. Construction of the CSSC allowed the reversal of the flow direction in the Chicago River and accommodated increased shipping.
*Barrier I is in design phase. Tentative location shown above.
The Electric Dispersal Barriers deter the inter-basin establishment of Asian carp and other aquatic nuisance species via the CSSC. The barriers are formed of steel electrodes that are secured to the bottom of the CSSC. The electrodes are connected to a raceway, consisting of electrical connections to a control building. Equipment in the control building generates a direct current pulse through the electrodes, creating an electric field in the water that discourages fish from crossing.
Click here to view a 3D model of barriers site.
See photos from the Electric Dispersal Barrier on our Flickr page.
There are three electrical barriers: Demonstration Barrier, Barrier IIA and Barrier IIB. The Demonstration Barrier has been operational since 2002. Due to its original demonstration status, it was designed and built with materials that were not intended for long-term use. Significant repairs were successfully completed in October 2008. In 2013, construction will begin on a permanent electric barrier, authorized by Congress as an upgrade of the Demonstration Barrier.
The Demonstration Barrier operates at 1 volt/inch, 5 hertz (cycles per second), 4 ms (pulse duration in milliseconds). Barrier IIA was placed into full-time operation in 2009. Barrier IIB was activated in April 2011 at the same operating parameters as Barrier IIA: 2 volts/inch, 15 hertz, 6.5 ms. In the fall of 2011, the parameters at Barrier II were increased from 2 volts/ inch, 15 hertz and 6.5 milliseconds to 2.3 volts/inch, 30 hertz and 2.5 ms. This increase was implemented after the completion of a study (Efficacy Study Interim Report IIA) that suggests this setting would be most effective at preventing all sizes of fish from crossing the electric barriers.
Multiple barriers are needed to provide redundancy. The barriers are complex electrical and mechanical systems and must periodically be powered down for maintenance. More than one barrier is needed so that at least one barrier can be active when another barrier, or barriers, is offline for maintenance.
Electric Barrier Parasitic Structures:
As part of the construction of Barrier IIB (photo), three underwater parasitic structures were placed into the CSSC. These structures, made of structural steel shapes and woven-wire rope, were placed downstream from Barrier IIA, between Barriers IIA and IIB and between Barriers IIB and I. They limit the extent of the electric fields generated by the dispersal barriers to the areas designed for fish deterrence.
Installation of parasitic structure
Occasionally, there are waterway restrictions within the CSSC due to maintenance operations of the barriers. View the U.S. Coast Guard waterway notices.