Streamflows at Island Park Dam

Streamflows at Island Park Dam

Many of you have asked about management of flows in the Henry’s Fork downstream of Island Park Dam during the summer and fall of 2013. During July, flows were high when irrigation water was being delivered out of Island Park Reservoir, but they were not nearly as high as the real-time streamflow values that appeared on the U.S. Geological Survey (USGS) water data web site at the time.

Similarly, flows have been dropped to very low levels over the past few weeks to facilitate storage of water in the reservoir, but these flows are not nearly as low as those that have appeared on the USGS flow data web site. Those of you who have watched both the USGS flow data and the U.S. Bureau of Reclamation (USBR) hydromet data—usually accessed through the “teacup diagram”—have also noticed discrepancies among the USGS flow data, the USBR flow data, and what actually appears to be flowing down the river.

These discrepancies all stem from the way streamflow is measured and reported on the web. 

By Rob Van Kirk, Senior Scientist