Most ponds are unstable and temporary habitats, which left unmanaged, become grown over with emergent and marginal vegetation, eventually succeeding to scrub and damp woodland. Many ponds in Britain are not natural, but have been created for a variety of reasons including water supply, industry, flood control and amenity, and rely on management to maintain them. In creating a new pond, the purpose of the pond and its subsequent management need to be planned at the outset. Just like the land environment, the freshwater environment of a pond can be managed as much or as little as desired.