What a great list of options ...

What a great list of options for removal of the hyacinths from the group, but another issue is to prevent future blooms once the problem had been addressed (which ever method is chosen), then the issue is future prevention.  Recently, a lot of Green Infrastructure/Low Impact Design (GI/LID) papers have been published for developing countries that focus on nutrient removal associated with use of Bioswales along rivers to prevent infiltration of nutrients and in these bioswales plants are selected that have high nutrient uptake. Here in the US some States are requiring agriculture land use abutters to streams and rivers to start using setbacks that have bioswales to capture stormwater runoffs inhibiting nutrient flow into the receiving body of water. This is especially true along those rivers that are using river water by downstream communities for drinking water.