Did you ever use an online planimeter tool or google area mapping tool to map out the current size of your pond in the picture? Knowing current surface area and current depth accurately (using plumb line, roap with foot markings on it, etc and a boat) will help decide how to meet your management goals whether it be amount of chemicals to purchase, which stocking program to use based on average depth, likelihood of winter kill, need for aeration etc.
You might also find when determining depth that the bottom is heavily silted or mucky and you then may want to move your plans over to a plan to drain pond, remove muck, remove all fish or unwanted fish at the time of drawdown of the pond, then start with a fresh bottom, and ability to control the fishery as well.
