Why manage a pond rather than leave it untouched?
Over a long period, it’s normal for a pond to fill up with silt and plant material. It will become overgrown and eventually disappear. Occasional work on the pond stops this happening, keeping the pond for people to enjoy in the future.
When it happens, this kind of work can look quite drastic. Trees around the pond may be reduced in size, plants on the banks cut back and heavy machinery brought in to remove material from the bottom of the pond.
The immediate outcome may not look good, but things will quickly grow back. The pond and its wildlife will benefit from the work for many years.
On the other hand, without management the pond could be lost entirely. Habitat loss is a major threat to species like the great crested newt, which depends on ponds. Great crested newts also need to be able to find food and shelter around the pond, and active management is important for this too.