Did Boise River top 9,870 cfs Wednesday at Glenwood Bridge? USGS says no

GARDEN CITY, Idaho (KBOI) — The National Weather Service said Wednesday that the Boise River topped 9,870 cfs at the Glenwood Bridge, which would make it the highest recording flow rate there since 1983.

But was it really a true, accurate record?

The USGS says field data shows flows were actually between 700-800 cfs below what the streamgage was reporting and was not an official record.

And on Thursday, we now know what caused the high reading.

"Our hydrographers measured streamflow yesterday at our Glenwood Bridge streamgage," the USGS said. "The data showed that the streamgage was accurately reporting river stage levels, but over-reporting streamflow. We have corrected the streamgage rating to accurately represent the changing conditions of the river."

Downstream debris was backing up water at the streamgage, slowing water velocity and increasing the area of the water across the river. Streamflow, measured in cubic feet per second, is the product of multiplying area by stream velocity."

The current record was set on June 13, 1983 with a reading of 9,840.

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