Why oh Wye?

The formerly pristine river Wye is reportedly under serious threat, having been contaminated by faeces from 'free range' chicken farms near its banks (https://www.theguardian.com/environment/2020/jun/20/its-like-pea-soup-poultry-farms-turn-wye-into-wildlife-death-trap)  The resulting algal blooms have converted its waters into a death trap for wildlife. It really should not be too difficult to stop this type of pollution.