Have you noticed the small dam on the South Skunk below SE 16th Street (Ames)? Could it have been constructed as a grade control structure (made necessary by channelization), or when the USGS stream gauging station was first installed? (Gauge records go back to 1952)
The first photo is looking upstream and east. In the second and third you'll see wooden boards that appear to be concrete forms. (Click to view larger images) And by the way, in most circumstances it is illegal to drive a motor vehicle in Iowa stream beds! (See Iowa Code 321I.14-1g.)
Newspapers.com didn't answer that question for me but it has turned up a lot of other interesting bits of history. Did you know that there was a Story County Conservation Committee, before the establishment of County Conservation Boards in 1956? Among other efforts the Committee led an Upper Skunk River Improvement Project, which involved the construction of rock dams for fish habitat. The first to be approved and constructed was located near the Soper's Mill bridge. Others were to be constructed near Story City and East 13th (Ames). I'll share a few of the news items I found but the organization seemed to disappear from the news. Could that be because the Ames Reservoir was first proposed in the 1930s?
(I've posted this unfinished, so if you happen upon it please know that it's a work in progress.)
(I've posted this unfinished, so if you happen upon it please know that it's a work in progress.)