October 2000 and August 2002
Survey of Sediment Contamination in the Chicago River - Chicago, Illinois

EXECUTIVE SUMMARY

In October 2000, the U.S. Environmental Protection Agency’s Great Lakes National Program Office (GLNPO) and the U.S. Army Corps of Engineers (USACE) coordinated a baseline screening study to provide a broad view of sediment conditions throughout the Chicago River system, specifically the North and South Branch, while targeting depositional zones within the river. Using GLNPO’s sediment sampling vessel, the Research Vessel (RV) Mudpuppy, GLNPO and USACE collected a total of six (6) surficial ponar grabs and twelve (12) sediment cores from twelve (12) locations in the area of the river beginning north from the Webster Street bridge continuing south to 32nd Street and including the Ship and Sanitary Canal. Sediment and ponar samples were analyzed for total organic carbon (TOC), oil and grease, dioxins and furans, heavy metals, polychlorinated biphenyl (PCBs), polycyclic aromatic hydrocarbons (PAHs), volatile organics, and pesticides. Additionally, sediment ponar samples were subjected to 28-day Hyalella azteca and 10-day Chironomus tentans whole sediment toxicity tests, as well as simultaneously extracted metals/acid volatile sulfide (SEM/AVS) tests.

Results of this study found significantly elevated levels of PAHs in most samples that were analyzed, up to 716 parts per million (ppm) in one sediment sample in the South Branch of the river. PAH concentrations tend to be higher in the deepest section of the sediment cores (> 54 inches) in the South Branch of the river, while samples collected in the North Branch indicate significantly lower PAH concentrations in both the ponar and cores samples. Samples analyzed for oil and grease show extremely elevated concentrations throughout the entire river system, with contamination increasing in the deeper sediments (>50,000 ppm in one sample). Heavy metals, including lead, cadmium, chromium, nickel, copper, zinc and mercury also indicate high levels of contamination throughout the entire sampling area, but based upon SEM/AVS analysis, it does not appear that these metals are bioavailable in the surficial sediments at most sampling locations. Finally, PCB results show elevated levels (up to 76 ppm in one location) in the deeper sediments in the North Branch of the river, with elevated levels also present in the South Branch (1 to 10 ppm). These results are consistent with previous sampling events in this area of the Chicago River, but most of the previous studies have been limited to chemical analysis of short sediment cores of minimal length and surficial ponar grabs. For this study much longer cores were collected to determine the vertical extent of contamination, and this data indicates that contamination significantly increases with depth in the Chicago River system.

Results of the 2000 toxicity tests indicate that neither H. azteca nor C. tentans were significantly impacted for mortality (organism survival), except at one sampling location in the North Avenue turning basin, ChR00-02, for H. azteca. However, this sample had extremely low dissolved oxygen levels observed for one replicate, for two consecutive days, during the testing and should be considered subjective. The measurement of growth for H. azteca also showed no significant difference when compared to the control group. Results from the 10-day C. tentans toxicity growth tests were not evaluated due to a lab error during the completion of the dry weight/ash free dry weight data. Additional samples were collected in August of 2002 and analyzed for whole sediment toxicity tests and results indicated that several samples had reduced survival and growth for both H. azteca and C. tentans. However, QA/QC concerns regarding the 2002 C. tentans toxicity samples relegate their use to qualitative purposes only. H. azteca results indicated that all samples were statistically significant compared to the control for the growth endpoint, and that three out of the five samples showed reduced survival.

A QA/QC review of the data indicates that most of the chemical and toxicity data are of good quality. However, as indicated above, 10-day C. tentans toxicity tests for growth were not evaluated in this report due to laboratory error. Also, the results for total petroleum hydrocarbon (TPH) should be considered unusable due to lab error. Finally, one sample analyzed for oil and grease (ChR00-05-A) had results that were extremely high (1,530,000 mg/kg) and were not used in this report.

Based upon the results of the data the following conclusions are made:

• PAH concentrations, especially in the South Branch of the river are elevated and potentially present an ecological and/or human health threat;
• PAHs, oil and grease, dioxins and furans and PCBs are the primary contaminants of concern, with metals a secondary contaminant of concern, identified in the sediments throughout the Chicago River system;
• Heavy metals including cadmium, copper, chromium, lead and zinc all have high levels of contamination, but based upon SEM/AVS analysis during this survey these metals were not bioavailable to the benthic community in the surficial sediment except in locations on the South Branch of the river. Additional SEM/AVS analyses should be performed for any future sampling that is planned to ensure that metals, in fact, are not bioavailable;
• Sediments in the Main Branch, near Lakeshore Drive, are significantly less contaminated than other portions of the river;
• PCB contamination appears to be higher in the deeper sediments in the North Branch of the river than in the sediments of the South Branch; and
• Overall, the surficial sediments are less contaminated than the deeper sediments throughout the river system for the primary and secondary contaminants of concern.

Based upon these conclusions, the following recommendations are made for this area of the Chicago River:

• Collect additional samples at ChR00-05 to determine if the extremely elevated concentration for oil and grease in the surficial sediments are accurate;
• Collect additional samples at ChR00-11 and ChR00-12 and section the samples according to how they were sectioned for this study (0-6 in., 6-18 in., 18-54 in., > 54 in.) to determine the vertical extent of contamination for PAHs, oil and grease, and metals in each section;
• Perform a benthic community assessment to more fully understand if the elevated chemistry levels are affecting the benthic community in the Chicago River system;
• Perform bioaccumulation studies in the North Branch to determine potential uptake of PCBs;
• Collect additional samples along the entire study area for toxicity testing and analyze using 10-day Chironomus tentans and 28-day Hyalella azteca; and; and
• Incorporate and evaluate other existing data sets to more fully understand the extent of contamination on the Chicago River.

EPA Home | Privacy and Security Notice | Contact Us