Ondiri Swamp, a water catchment area vital to Nairobi’s water supply, could soon dry up if human encroachment is not stopped.
When the Star visited the wetland in Kiambu county, it was a scene of encroachment. People had taken up most of the swamp.
Muguga Community Forest Association chairman Simon Kamonde said the swamp will disappear in 10 years if it is not protected.
It used to cover 74 acres, but now it’s is only 37 acres — half the size.
Most of the wetland is covered by aquatic plants, rushes, papyrus and water grass.
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Hundreds of greenhouses surround the swamp, as well as illegal water abstractions and banana gardens. Pesticides from farms drain into the swamp.
Encroachers have ignored regulations protecting wetlands, seized land and planted thirsty fast-growing eucalyptus trees.
A nearby river is being filled with soil to create space for commercial development.
Kamonde said Kikuyu town, where the swamp is located, lacks proper sewer lines and sewage pours into the swamp. Construction of the Kikuyu Bypass has contributed to degradation of the swamp.
Migratory birds used to breed at the swamp, but they no longer visit.
Kiambu acting Environment CEC David Kimani said the county is establishing the boundaries before taking action.
Kimani told the Star he is not sure if the swamp has been gazzetted.
According to wetland regulations, human activity is banned within 30 metres of a river or lake and 60 metres from the Indian Ocean.
East African Wildlife Society executive director Julius Kamau said Ondiri Swamp is a key ecosystem.
The main outflow of the wetland is to the south and east, where several streams join to form the headwaters of Nairobi River, he said.
It is linked to Kikuyu Springs, a major source of water in Nairobi.
Kamau said together with other streams from Ondiri wetland, the swamp forms a significant catchment area for the Nairobi River.
He said the swamp provides water for domestic use, irrigation and livestock, particularly during the dry season.
The lobby has expressed alarm about the swamp and has partnered with the Kenya Wetlands Forum to educate the community on protecting wetlands.
In 2011, the Water Resource Authority said,“Land use changes, encroachment on Ondiri Swamp and increasing groundwater abstraction threaten sustainability of Kikuyu Springs.”
It urged that recharge areas be protected against degradation. The authority also recommended a reserve volume should be declared for the Kikuyu Springs Aquifer, related to the swamp, to regulate the amount of water abstracted.
"The total annual recharge is 13.2 million cubic metres, against abstraction of 6.7 million cubic metres from boreholes and 2.3 million cubic metres from Kikuyu springs discharged as much as 68 per cent of the annual recharge is abstracted, which should raise concern in view of the lack of a reserve declared for the aquifer,” the authority said.
It said abstraction in the northern zone will have more impact on the system than abstraction in the lower zone around Ondiri swamp and Kikuyu springs and should be regulated.