Up in the Cascades, there are a bunch of dams.  The rivers have been dammed to provide hydroelectric power.  The lowest dam was not terribly cool looking but the dams higher up the pass looked a lot more like you would expect a dam to look.  One of them was easy to see although it was deep in shade while the rest of the scene was very bright.  HDR seemed to be the way to go.  The last dam we passed was visible from the highway but it was hard to get a clear look at it without some vegetation getting in the way.  Time to reach above your head while standing on a rock and using the Live View mode to try and see what you were shooting.  Limited success but at least you could see something.