Chicago River
USGov
1994
<a rel="nofollow" class="external text" href="https://il.water.usgs.gov/nawqa/uirb/pubs/reports/WRIR_96-4135.pdf">Surface-Water-Quality Assessment of the Upper Illinois River Basin in Illinois, Indiana, and Wisconsin--Pesticides and Other Synthetic Organic Compounds in Water, Sediment, and Biota, 1975-90</a>, page 21 (PDF page 30)