A large drainage area requires a pond big enough to manage not only the normal flows but must also have sufficient storage capacity to handle flows from heavy rainfall to protect the dam from failure. Designing a safe structure on a small pond with a large drainage area is usually impossible or cost prohibitive. Ponds do need an adequate supply of fresh water to be successful. Small streams or springs with year round flows provide the best source of water. Ponds dependent on surface runoff often fluctuate during dry times causing management problems for the owner.
Property lines are another important consideration.
It is often necessary to restrict the size of a pond or recommend that it not be constructed due to limited space. Landowners should remember it is illegal to impound water on others or to direct storm water from emergency spillways to another persons property without permission from the owner. Downstream property must also be checked to ensure that if the dam was to fail there would be no loss of life or damage to homes, roads, utilities etc. Soils are a key element in pond construction, the soils in the reservoir must have ability to hold water. Suitable soils for a cutoff trench, foundations and the embankment must be available at or near the pond site to construct a safe dam and reduce costs.