Abstract: Settler colonialism in Kenya and elsewhere was, amongst other things, an environmental regime based upon specific ideologies of resource use and availability. The resource rights and requirements of nomadic and pastoral communities were written away in favor of extractive uses rooted in capitalist production, as well as a mythical ideal that settlers could create a facsimile of pre-industrial Britain overseas. This article argues that settlers’ pursuit of these goals in the region of the Ewaso Ng’iro river led to a discursive and material erasure of indigenous livelihoods and claims to water downstream. In removing, diminishing, and eliminating the flow of the river into the Northern Frontier via large scale irrigation operations, the settlers of the Nanyuki region placed the river within an ethnonationalist ideology of water that elevated their new European Eden above all else. By tracking the slow diminishment of the Ewaso Ng’iro’s water level and the settler-nomad contestation over it, this article shows that the possible erasure of a rural population whose way of life was antithetical to both the racial and economic priorities of settlers was a necessary side-effect for the realization of a proto-econationalist ideology emanating from the upper middle class and elite settlers of the Ewaso Ng’iro’s catchment area.