Glug dear,
The most powerful water management plant is the willow. You can terriform with it. Within minutes you can change the course of a stream or river just by taking cuttings and sticking them in the shore rocks and soil. Willow is a necessary component of ponds. They respire cooling the pond, act as roosts and stabilize banks.
Willow is the easiest to plant and can be cut year around. You select last year’s green shoots and make an oblique cut. Remove leaves not damaging the bark. You can directly spear this shoot into the ground or use a piece of rebar to drill a hole. Place three nodes underground and two above. Most willow cuttings will spout if they have water.
I have seen many streams digging themselves into the ground having lost their meander. Bundles of willow alternating stem tip to stem bottom wrapped with baling twine can be place directly in the stream and covered with gravel. This acts as a water break. Placing cuttings on alternating banks will restore the meander of a stream reducing its energy and thus the stream will not erode the bank. When used in conjunction with sedge the incoming stream into a pond will lose its nutrients reducing weed growth.
Willow produce seed that can be a weed (cranberry culture); however, this seed is top forage for many animals. Willow is the most resilient tree that can be grown as a shrub or tree. You can trim it and it will respond having more leaves and sprouts. The weeping willow is often used around ponds and suggests a large beautiful fountain.
Froggie, in my blogs I have described the log, willow, sedge, and river rock. Most ponds can be restored using these components. It matters little where in the world you are, you can find them. There is some work in collecting them but they exist generally within walking distance to your pond.
PonDoc from the pond