Plastic floating papyrus islands to clean L Naivasha

A project to create plastic floating islands containing papyrus plants known to clean dirty water is promising to not only clean Lake Naivasha but provide feeding options for aquatic animals in a lake which is chocking with filth.

The project which involves Finlays Horticulture Kenya aims to recreate the water-cleansing services of papyrus as artificial floating islands. Finlays customer and German retailer; REWE, is funding the papyrus restoration partnership between Finlays and Dr David Harper, a senior lecturer at the University of Leicester.

The islands which have been ordered from Eli will be anchored once the papyrus has been planted, in the mouth of the main river, the Malewa, to trap silt before it reaches the lake. The roots of papyrus islands also act as important fish nurseries and feeding grounds, whilst their 5-metre tall stems hold a rich biodiversity of birds such as warblers and kingfishers making the project beneficial to both people and nature.

Papyrus originally inhabited the whole perimeter of the lake and acted as a physical filter for surface run off, and added additional value to remove nutrients. In the last few years, much of the papyrus has been removed to gain access for the lake for tourism and it is being overgrazed by buffalo and domestic cattle belonging to pastoralists. The young shoots get rapidly consumed and hinder the natural regeneration as the lake level varies through the riparian zone. So the idea of anchoring papyrus islands offshore would make them less vulnerable to bovines and encourage regeneration.

Dr Harper said: "Lake Naivasha is a freshwater lake of around 100 km2, and although once crystal clear and surrounded by papyrus, it has suffered in the past 30 years. A major factor is that Naivasha has been the fastest growing town in Kenya as a result of the bonanza of horticulture, cut flowers for export, which is now one of Kenya's top three earners of foreign exchange. As job opportunities have grown, the human population has grown more than twenty-fold, and settlements have sprung up in a haphazard fashion, clearing papyrus. In the same 30 year period, the population of buffalo native to the lake has trebled, knocking down the papyrus to eat it.

As well as having many commercial uses, papyrus is a most valuable natural filter for dirty water. A common plant of tropical wetlands, it is capable of acting like a sewage treatment works all on its own. The restoration project at Lake Naivasha entails papyrus being planted in islands made of recycled post-consumer plastics, such as bottled water containers, made by a new company called "Floating Islands International" (FII).

Major flower growers are well aware of their responsibilities to the fragile environment of Lake Naivasha, and their reputation amongst consumers in Europe. Finlays, a major UK-owned tea producer and flower grower, has turned their concern into reality by growing papyrus from cut culms (pieces) in their own artificial wetlands treating waste from their processes, such as workers canteens and laundry.

Finlays also has Fairtrade status, and major European retailers, such as REWE, only buy Fairtrade flowers. However, Fairtrade does not require that farmers show a concern for the ecosystem from which the raw material for their product comes outside their own gates.

Although the new Kenyan Water-Act requires that they pay for this valuable "ecosystem service" - clean water - this does not directly pay for ecosystem restoration." The scale of the project depends very much on the pilot work being undertaken. We are also looking at the possibility of anchoring "natural" islands that detach themselves from the shore with wind and lake level changes. Some of these are quite large and could be used to fast track for example papyrus farming.

However, the artificial islands will still be important to reinstate areas that have been destroyed. Interestingly the floating islands also provide a refuge for fish breeding promising to encourage an industry that is at present in need of better control and increased stocks.