Natural pond is a self-sustaining ecological system, thriving to equilibrium (rather than sterility).
Such pond is a stable system, able to withstand climate fluctuations and human mistakes. It is easy to maintain, forever changing through seasons and hours, attracts wild life (and people) and contributes to biological diversity.
The heart of such a system is the constructed wetland, serving as the filter and source of stability and health. Constructed wetland is considered the best carbon emission preventer and gathers the highest carbon credit possible.