# Ewaso Ng'iro and Lagh Dera

> Ewaso Ng'iro: Kenyan river from Mount Kenya to the Lorian Swamp, continuing as Lagh Dera through North Eastern Kenya into Somalia.

Source page: https://calankii.com/en/regions/ewaso-ngiro/
Last checked: 2026-11-12
Publisher: Calankii (https://calankii.com)

## Course

The Ewaso Ng'iro starts at Thome, near Nanyuki in Laikipia County, where the Naro Moru River from Mount Kenya meets the Ngarinyiru from the Aberdare range ([Wikipedia: Ewaso Ng'iro](https://en.wikipedia.org/wiki/Ewaso_Ng%27iro)). It is fed partly by Mount Kenya's glaciers and flows east. Below Saricho it spreads into the Lorian Swamp, a large wetland ([Wikipedia: Ewaso Ng'iro](https://en.wikipedia.org/wiki/Ewaso_Ng%27iro)).

The catchment crosses seven dry and semi-dry districts: Meru, Laikipia, Samburu, Isiolo, Wajir, Marsabit and Garissa ([Wikipedia: Ewaso Ng'iro](https://en.wikipedia.org/wiki/Ewaso_Ng%27iro)). Below the swamp the river is seasonal; its bed through Somalia is called Lagh Dera ([Wikipedia: Ewaso Ng'iro](https://en.wikipedia.org/wiki/Ewaso_Ng%27iro)). Wajir and Garissa are two of the three counties of former [North Eastern Province](/en/history/northern-frontier-district-1962-1967/), where most people are Somali ([Wikipedia: North Eastern Province](https://en.wikipedia.org/wiki/North_Eastern_Province_(Kenya))).

The name comes from the Maasai language and means "river of brown (muddy) water" ([Wikipedia: Ewaso Ng'iro](https://en.wikipedia.org/wiki/Ewaso_Ng%27iro)). Its upper basin covers about 15,200 km² ([Wikipedia: Ewaso Ng'iro](https://en.wikipedia.org/wiki/Ewaso_Ng%27iro)).

## Water and wildlife

The river is the largest of Kenya's five water catchments ([Wikipedia: Ewaso Ng'iro](https://en.wikipedia.org/wiki/Ewaso_Ng%27iro)). Its water keeps the Samburu, Shaba and Buffalo Springs national reserves green in dry country ([Wikipedia: Ewaso Ng'iro](https://en.wikipedia.org/wiki/Ewaso_Ng%27iro)). It also feeds Lake Ol Bolossat, the only lake in central Kenya, which was declared a protected area in 2018 ([The Star, Feb 2018](https://www.the-star.co.ke/news/2018/02/20/why-lake-that-feeds-ewaso-was-declared-protected-area_c1708470); [The Standard](https://www.standardmedia.co.ke/article/2000172240/discovering-central-kenya-s-only-natural-lake)).

## Less water downstream

Studies of the basin report that its tributaries dry up more often in the dry season, rain has become less reliable, and low-season flow has fallen ([Wikipedia: Ewaso Ng'iro](https://en.wikipedia.org/wiki/Ewaso_Ng%27iro)). Much of the water is taken for irrigation in the upper catchment, where the population has grown fast, leaving less for herders and wildlife downstream ([Wikipedia: Ewaso Ng'iro](https://en.wikipedia.org/wiki/Ewaso_Ng%27iro); [NETWAS, 2005](https://web.archive.org/web/20070524041456/http://www.netwas.org/newsletter/articles/2005/09/5)). The African Development Fund puts Kenya's renewable fresh water at under 650 m³ per person per year, one of the lowest in the world ([Wikipedia: Ewaso Ng'iro](https://en.wikipedia.org/wiki/Ewaso_Ng%27iro)). A 2026 study in *Hydrology and Earth System Sciences* looks at water in the basin ([HESS, 2026](https://hess.copernicus.org/articles/30/2225/2026/)).

For Somalia's main rivers, see the [Jubba River](/en/regions/jubba-river/) and the [Shabelle River](/en/regions/shabelle-river/).

## Sources

- [Wikipedia: Ewaso Ng'iro](https://en.wikipedia.org/wiki/Ewaso_Ng%27iro)
- [Wikidata Q1757939](https://www.wikidata.org/wiki/Q1757939)
- [The Star, Lake Ol Bolossat protected, 2018](https://www.the-star.co.ke/news/2018/02/20/why-lake-that-feeds-ewaso-was-declared-protected-area_c1708470)
- [Hydrology and Earth System Sciences, 2026](https://hess.copernicus.org/articles/30/2225/2026/)

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