Report on Illinois River sediment quality could aid dredging and other projects

An Illinois State Water Survey (ISWS) crew retrieves a coring tube filled with sediment from a backwater lake on the Illinois River. Photo courtesy of John Marlin

A new Illinois Sustainable Technology Center (ISTC) report presents sediment quality data collected along the Illinois River at 125 locations between Hennepin and Beardstown, Illinois. The report will help consultants and organizations plan dredging and other projects along the river, especially in backwaters.

The report, Chemical, Physical, and Agronomic Characteristics of Middle Illinois River Sediments, contains detailed information gathered for various Illinois River restoration studies between 2004 and 2010. The data in the report supported projects that provided dredged soil for the Pekin Landfill, a lake front park in Chicago, and Banner Marsh State Fish and Wildlife Area. The report is available in IDEALS, the University of Illinois’ institutional repository.

Researchers collected samples in backwater and main stem lakes where sediment was deposited over former floodplain and shallow, pre-settlement lakes. Water surface area and depth changed greatly beginning in 1900, due to Lake Michigan diversion and lock and dam construction. Core samples were taken to a depth of as much as 10 feet. Each core was photographed to show layers deposited over time.

An opened sediment core in an ISWS laboratory at Peoria. The sediment will be sampled for chemicals, fertility, and a variety of physical properties. Photo courtesy of John Marlin

To determine the pollutant concentrations in sediments, chemical analysis was completed for semi-volatiles, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), pesticides, and inorganics, which were mostly metals.

Physical properties such as moisture content and unit weight were determined every 40 cm. Agronomic parameters including particle size, consistence, Munsell color, and sand content were obtained every 20 cm when possible. Fertility analysis included pH, percent organic matter, total exchange capacity (TEC), and extractable nutrients among others. Because the individual samples are widely separated, they provide an indication of expected quality at a given point, although projects will likely require additional localized sampling.

The data report is a companion to Beneficial Use of Illinois River Sediment for Agricultural and Landscaping Applications, which ISTC released in 2018.

The report was prepared by John C. Marlin, retired from ISTC; Robert G. Darmody, retired from the University of Illinois Urbana-Champaign Department of Natural Resources and Environmental Sciences, and James A. Slowikowski, retired from the Illinois State Water Survey (ISWS). ISTC and ISWS are divisions of the Prairie Research Institute at the University of Illinois Urbana-Champaign.