I'm not sure of the licence specifics related to downstream water, but in general:
The impact on downstream water is almost entirely positive, the leaky dams they build filter sediment and excess nutrients (often from fertiliser run off).
They also smooth out peak water flow to help alleviate downstream flooding. Obviously this comes at the cost of flooding areas behind their dams, but this can also be positive, because in the increasingly dry summers, the ponds they create help keep the land upstream cooler and wetter.
The beaver site in Ealing, London was mostly funded because it was a cheaper solution to help with downstream flooding than equivalent hard infrastructure and a significant cost of that project was the fence to keep them in.
Even fish which need to navigate upstream, can leap these dams because they have co-evolved with the beaver, and also beavers are vegetarian so don't predate the fish.
Obviously the main problem, is because in the UK we wiped them out, we've not co-evolved with them, hence the problems of them flooding land that would regularly have flooded, but we have decided to use for other purposes.
I highly recommend anyone who's interested in ecosystems go visit an established beaver site, the mosaic of habitats they create can support large amounts of biodiversity.
The impact on downstream water is almost entirely positive, the leaky dams they build filter sediment and excess nutrients (often from fertiliser run off).
They also smooth out peak water flow to help alleviate downstream flooding. Obviously this comes at the cost of flooding areas behind their dams, but this can also be positive, because in the increasingly dry summers, the ponds they create help keep the land upstream cooler and wetter.
The beaver site in Ealing, London was mostly funded because it was a cheaper solution to help with downstream flooding than equivalent hard infrastructure and a significant cost of that project was the fence to keep them in.
Even fish which need to navigate upstream, can leap these dams because they have co-evolved with the beaver, and also beavers are vegetarian so don't predate the fish.
Obviously the main problem, is because in the UK we wiped them out, we've not co-evolved with them, hence the problems of them flooding land that would regularly have flooded, but we have decided to use for other purposes.
I highly recommend anyone who's interested in ecosystems go visit an established beaver site, the mosaic of habitats they create can support large amounts of biodiversity.