Jeff,

The photos tell the story. That dam is way different than I pictured it.

Still not sure about the depth of the water behind the dam. If it's approaching 10 feet, the pressure is powerful and relentless. It will work 24/7 trying to escape and wash out the dam. If the 16' depth you mentioned is largely below the ground and the water at the dam is well under 10 feet, a repair may be possible without wrecking your nice dam.

Either way, drawing down the pond is inevitable, more or less.