Effective November 14, 2014...the gage zero datum at the U.S. Geological survey(USGS) streamgage on the Des Plaines River near Des Plaines IL will be changed by 10.0 feet. Gage zero datum is a horizontal surface used as the zero point for measurement of river stage, also referred to as gage height.
The physical location of the USGS streamgage near Des Plaines IL has changed. The gage is now located at the Euclid Avenue/West Lake Avenue bridge, approximately 0.4 mile upstream from the previous location. The move was necessitated by the removal of dam #2 by the Illinois Department of Natural Resources beginning on May 28 2014. At the current datum, low flows are resulting in the reporting of negative stages. The USGS will be adjusting the zero datum used to reference gage heights, flood stage, and impact levels. The zero datum will be changed from 626.31 to 616.31 feet to avoid negative readings.
Impacts to users
All existing flood and impact stages will be increased by 10 feet. New flood thresholds will be as follows:
In addition, it was determined that some minor impacts begin at levels slightly below the existing action stage. Thus, the new action stage will be adjusted to 13.5 feet.
Frequently Asked Questions (FAQ)
Will river stages I see on the AHPS hydrograph page for Des Plaines change?
These planned changes have been coordinated with other agencies including the U.S. Geological Survey and the Illinois Dept. of Natural Resources.
River stage and forecast data can be found on the Advanced Hydrologic Prediction Service page. River stage data is also available from the USGS here. Learn more about the USGS Streamgage program here.
If you have any questions or comments about this change...please contact: