There is no single answer to this question. Depth of a farm pond depends on several factors such as the intended use of the pond, geography of the area, size of the pond and the local rules and regulations governing farm ponds. Although the government dictates minimum depth for farm ponds, they don't address maximum depth.
Ponds deeper that 12 to 14 feet are not productive for fishing because they have water quality problems, such as the amount of dissolved oxygen there. According to the National Resources Conservation Service (NRCS), farm ponds sized half an acre should be about six to ten feet deep for best results. For stocking fish, they advise a minimum depth of eight feet over 1,000 square feet. The exact depth will differ according to the type of fish.
Swimming and Waterfowl Ponds
According to Washtenaw County Conservation District, a waterfowl pond should not be deeper than three to five feet. A pond used for swimming should be 10 to 15 feet deep.
Recommended Minimum Depth
According to the United States Department of Agriculture (USDA), the minimum depth required for a farm pond is based on the geography of the area. It varies from five to 14 feet, from wet to arid land respectively.