Right where the Colorado River flows into the mouth of the Grand Canyon, an inconspicuous 20-foot-high concrete tower rises from the riverbank.

Inside the tower is a U.S. Geological Survey streamgage that will mark its centennial year of monitoring the river on October 1, 2021. At a time when the Roaring Twenties were in full swing, the streamgage began collecting information about the water’s level and flow. USGS scientists chose the site in 1921 because it was readily accessible and strategically located to study the hydrology of the Colorado River drainage basin.

Click here for more….