We just bought 90 acres and are looking to build a pond. Been reading up a lot and had a question. If a 1/2 acre pond is built on flat ground, what is the purpose of the dam? And does it only go on one side?
Some ponds are referred to as "dug" ponds, where the majority of the pond containment is a hole in the ground. That is opposed to damming up a ravine with a dam where the purpose of digging the hole is as much for obtaining dam material to construct the dam as it is to make the pond deeper. In a dug pond, what appears to be a dam may be just a place to pile the excess dirt from the hole.
When you say your ground is flat with only a half foot rise, that does not mean the pond will not fill with runoff. As long as the terrain has any slope at all, water is going to run somewhere if it rains more than what can soak into the soil. You can actually have lots of runoff on fairly flat ground but that is going to be more dependent on the type of soil (if it is sandy most rain will simply sink into the soil) and the size of rain events.
If you have flat ground with good water percolation and rarely get significant rain events you will not have much runoff. On the other hand, if 2-6" rain events are common, ground that is fairly flat can be prone to flooding.
Are there any indication of wash out areas? This would indicate water flow.
Your local NRCS office will have information on the suitability of runoff and the size of rain events with some guidelines for the watershed area to support a pond. That is if you have ponds in your area. If there are no other ponds around, there may be good reason for it. Then you might be looking at a well and a pond liner to get it done.
