On Feb 13, 2006, at 10:15 AM, Sean Dunham wrote:

> The images of the dams in question are now posted on our website -
> http://www.ccrginc.com/#news .  We have seen them referred to as
> Roller Dams as well as Check Dams.

You've probably checked James Leffel's "Construction of Mill Dams",  
published in 1874 and 1881 for the info it has. From the photos, the  
empoundment area is fairly low. Are there roads leading to either end  
of the dam? Any trace of a mill associated with it? What's the  
immediate reason for construction? Is this one on its own in the  
watercourse or are there others at the next contour interval up and  
down along the flow?

If it's in the proverbial black hole with nothing leading to it,  
nothing powered by it and nothing near it, then you might look at  
navigation improvements as the proximate cause.

Lyle Browning