My neighbor up the road couldn't set foot on his garden for two months last Spring and he had already planted some things. His garden is perfectly flat/level. Mine's on a slight grade so it's not as bad. One year when I didn't grow anything, it rained a LOT and I had a 1 inch hole in the garden area where water bubbled up for over a week. Clay subsoil, with rocks of all sizes and lots of Springs in the around here. Creeks and rivers were all high that year.
Sounds like you have an artesian spring! Pond for you goats and ducks.