Pond Boss Forums POND CONSTRUCTION Building a dam Guard for Drain Pipe

We are close to finishing construction on about a 25 acre lake and have a 48" drain pipe with a 54" stand pipe on the inside of the dam. There is a 12' by 20' pipe with 12" gate valve installed at the base to allow it to be drained or lowered when needed. The welder just welded 4 pieces of rebar over the end of the 12" drain pipe to help block larger objects coming through but I want something a bit more substantial. I am considering going back and digging out a larger area infront of the drain and lining with large rock and then having him build a larger cage to help keep turtles, and large and small sticks etc. from blocking the pipe. We have also already noticed that the valve itself can easily get some silt/dirt in the channel that seals it off so that it is hard to get it to seal all the way sometimes. Anyone dealt with similar issues and have good solutions?