Warning: Basin delineations in Illinois from December 8, 2017 to February 20, 2018 may have been in error. Please check your basin delineations.


In mid-February the StreamStats team determined that some basins in Illinois were not delineating correctly. These basins were typically larger basins and were not including the upstream HUC8 basin in the delineation; therefore the resulting basin was substantially smaller than it should have been. Unfortunately the StreamStats team is unable to identify which of the HUC8 basins were affected.  For reference, the 66 HUC8 basins are shown here for Illinois.