[5] In the late 1800s the alluvial plains near the lake were occupied by the Njemps people, an ethnic group related to the Maasai.

They used a brushwood barrier to raise the level of the river and let the water flow over the flat ground.

[6] The British explorer Joseph Thomson visited the Perkerra in the nineteenth century with his caravan and bought grain from the local people, grown using their proven system of irrigation using basins and canals.

Severe overgrazing, drought and locust invasions led to a food crisis in the late 1920s.

[10] There is now scarcely any vegetation in the lowlands for eight or nine months of the year apart from swamps in the lower reaches of the Molo and Perkerra rivers and along the lakeshore around their mouths.

The swamps, mostly covered by perennial grasses and flooded for only two months of the year, provide grazing for herders.

The herders claim that the irrigation dams have reduced the level of annual floods and thus cut down the amount of pasture.

[12] With little plant cover on most of the lower levels, the soil erodes easily and much sediment is deposited in Lake Baringo.

It was thought that the Chemususu dam project on one of the main tributaries of the Perkerra, due to be commissioned in 2011, would mitigate the effect of the reserve on water users while ensuring that the river did not dry up altogether.