Indianford dam

In general, you don't want to mess with the main width of the dam. Across that whole width, there is large rock rubble (in the landing zone and outflow) which is used to reduce/eliminate hydraulic scouring of the riverbed. However, the left-most part of the dam has releasable gates. Depending upon flow, and which gates on the dam are open, there can be a sweet wave where the outflow from those gates hits the pool below.

Gauging can be a bit funky, since the nature of this wave will depend upon how many (and possibly which specific) gates are open, and also upon the downstream river level.
  (Reported flow was 3440 cfs when photo was taken, and it did not look at all friendly or surfable.)