The fastest cycles with your loader will be achieved by dumping going forward and spreading the dirt with the bucket in the dumped position and not back dragging it. Basically you want your load at the proper height so that when you dump, your bucket cutting edge is at the grade you desire and you can push the material in front of you carrying grade as you go. It takes a bit of practice to be proficient at it but once practiced you will be able to easily and consitently carry grade this way and as you are backing up you can return your bucket to a digging position and be ready to load again. Another thought is to rent a track loader to dig your pond, this way you only have to use one machine (someone elses) to dig it and build your dam. IMHO a good track loader with a skilled operator is often more useful than a bulldozer.