Pond Boss Forums INTRO Questions & Observations Concrete Spillway with Slow Leak

It looks to me like those "blocks" might have been bags of concrete that were put in place to raise the level of the pond years and years ago. What is the history of the pond and how long have they been in place?

I believe any fix will require the water to be drained, the concrete and blocks cleaned with a sandblaster or muratic acid to get a good clean surface for whatever you want to use to bond them together and create a waterproof seal.