Photos definitely helped.
I liked the last one with your dog. I knew that some breeds were classed as "water dogs", but I had no idea they had dogs now that could diagnose spillway pipe problems!
After it quits running, I would definitely re-attach that last section of pipe. It looks like you also need a way to stop erosion at your pipe discharge.
One way is to build a little splash pool - if it would hold water most of the year. The other way is a splash block or splash pile. (I can't remember the correct term.) You could make a little depression and roughly line it with some of the flat rocks in the pictures. You want the running water to splash off of the rocks instead of eroding your soil.
Looks like your dam is much safer now that you are addressing the problem!
P.S. Beautiful pond and location!
