I fully support Ross ...

I fully support Ross Chandler's reply to the issue of Hyacinth over-growth in Lake Tana. My experience with excessive growth of macroalgae in the Peel-Harvey estuarine system as well as experience in managing algal and vegetation blooms-outbreaks in the waterways of south-western Australia, would support three practical strategies to get hyacinth under control. 1 - mechanical harvesting . There are a number of suppliers who build harvestors and attending barges to allow large harvesting operations and they can be purchased reasonably "cheaply" BUT you will need to train and develop operators to do this efficiently. You will also need to be careful about fuel supply and storage. Make sure to compost the vegetation away from the Lake with no return water able to re-gain entry into the lake and tributaries. 2 - spot applications of herbicide may work but it may be better to have human labour manually remove smaller drifts of the weed rather than load up the Lake with more nutrients and organic matter as well possible degradates of herbicide from spraying. 3 - a significant catchment and public education program will need to occur to reduce deliberate and accidental release of the weed into waterways feeding the Lake. This includes surveys around the lake to remove seeding populations in small lakes and impoundments etc that when they flood overflow into tributaries. You can contact me if you would like more information on suggestions to help remove and control this and other vegetation blooms on- tro56712@bigpond.net.au.