Went to dig up what I thought was an old garden bed and instead found a 5x5ft concrete basin that’s 1.5ft deep.
Looks like the concrete was painted blue at some point. I believe it is an old man-made pond. House has never had septic or well. It’s exactly 21ft from the house. Gutter system is buried but does not reach this far. There were plants surrounding it at one point but have since been dug up. House was built in 1984. Any ideas? I tried looking at old satellite photos but there were too many trees to see anything