It sounds lovely and the flowers look lovely, but it can be a pest, as many people in tropical and sub-tropical areas will know. It can grow extremely rapidly to form mats which may be as much as two metres thick.
It has caused a problem in 2005 on Lake Victoria in both Kenya and Uganda. It was controlled using mechanical and biological means, with a 90% success. Given that it spreads quickly and also floats around, it's not surprising that it once again is causing a problem.
The problems it causes are:
- Hindering water transport
- Clogging various water supply systems
- Harbouring various diseases
- Causing water to evaporate nearly twice as quickly through transpiration
- Impeding fishing
- Unbalancing the ecosystem and reducing biodiversity.
- Biological control using a variety of insects and fungi. This method can take a long time to have an effect.
- Chemical control but this may harm the environment.
- Physical control by removing the weed - only suitable for small areas
- Paper - the fibre needs to be blended with waste paper or jute to produce a reasonable quality (Bangladesh, Philippines, Indonesia, and India)
- Fibreboard - for general purposes indoors, and a bituminised version for roofing is being investigated (Bangladesh)
- Yarn and rope (Bangladesh)
- Basket work (Philippines)
- Charcoal briquetting - under investigation (Kenya)
- Biogas production - under investigation (Bangladesh)
- Water purification
- Animal fodder (China, Malaysia, Indonesia, Philippines, Thailand)
- Fertiliser (Sri Lanka)
- Fish feed - Chinese carp, tilapia, silver carp, and silver dollar fish will all eat water hyacinth.
Sources: IRIN and PracticalAction
A very recent (January 2016) TED talk by Achenyo Idachaba covers some of the issues and offers one solution. Achenyo Idachaba is the founder of MitiMeth, a social enterprise which aims to transform the ecological problem into enployment and products in Nigeria.