To do this in one of our ponds i bought a rubber coupler (that overflow pipe is 8 inch cast iron) to connect the pipe to a piece of PVC. That short piece of PVC then slipped into a 22 degree PVC elbow ($95 delivered) and then a final piece of PVC was slipped into the top of the elbow cut to the length needed to raise the water to the desired level. I had a scrap piece of 8 inch schedule 40 PVC so i did not have to buy that. The coupler (bought on Amazon) and the elbow (bought from PVC Pipe Supplies.....google PVC 22 degree elbow in the appropriate diameter and that company will likely pop up) cost a total of about $120.

The beauty of the slip in elbow is that you can raise the water in the spring by just slipping the PVC into the top of the elbow (watertight with no glue needed) and then if you wish to kill/freeze some shore weeds in the winter just pull it back out and do a winter "drawdown".

Works great and not expensive. I could have purchased a cheaper coupler but decided to go with better quality. Your overflow pipe looks nearly horizontal so maybe a 45 degree elbow would be better. This is a very easy improvement to make. Nobody local carried the 8 inch PVC elbow i needed....not even the professional plumbing places.