Chemical dumping, irrigation, killing Lake Ziway


Commercial and small scale farming is killing fish in Lake Ziway.
The 31km long and 20km wide lake faces a critical decrease of fish production as farmers use the lakes water for irrigation.
19.3 million cubic meters of water pumped per annum for  livestock, domestic, irrigation, commercial farms and construction. The water is estimated to be worth over USD 89 million.  However the farms are not being charged for taking water from the lake. Form the pumped water 54.1 % is being taken by commercial farms growing flowers and grapes near the lake while 31% is taken for small scale farming.
The recent study conducted for the Ministry of Environment reports that the lake’s annual fish production has decreased to 1,000 tons from 3,500 tons. This has occurred as the lake’s depth has decreased to four meters from twelve.
This has caused fish to die off and some species to become extinct. Previously the lake had 12 species of fish. Now that number is down to three; the Carassius, Catfish and Tilapia.
Meanwhile overfishing is occurring at the lake as beach seines, gillnets and loglines, used for fishing, disturb the fish.
If that were not enough, Chemical waste is being thrown in bulk from the farms to the lake as over 8,000 trap fish to eat in the lake.
Over 18,300 people bathe in the lake and 5,158 boats trips are carried out per year.
The report states: the major cause for the accelerated water quality changes in the lake were identified as human impact in the catchment of the lake. This includes land use changes, particularly removal of vegetation cover, irrigation, diversion of inflows and industrial use of the water which have caused a decline in water quality and quantity directly impacting the current change in fish composition and abundance. Therefore, sustainable utilization and conservation measures should be taken. In Lake Ziway, large numbers of small sized fish of all species are being exploited and proper management actions are required to protect the immature fish. Particularly, the size of the captured stock should be determined taking in to consideration the size at first maturity of fishes.
A  swift ecosystem payment service and tight regulation should be applied to reduce the  discharge of  toxic chemicals into the lake.  Many pumps are abstracting freshwater from the lake including commercial farms. Even during the rainy season water for horticultural crops is collected from the lake. Hence, the current irrigation practices in the upstream areas have considerably reduced the volume of the inflowing water from the Meki and Ketar River and the lake itself, critically impacting the water level of Lake Ziway. As a result, the lake ecosystem is being affected by catchment degradation, siltation, and imbalance between water inflow and outflow.