Upper Tana Nairobi Water Fund

The Upper Tana-Nairobi Water Fund allows urban users to invest in upstream watershed conservation efforts for the benefit of farmers, businesses and more than 9 million Kenyans who depend on the Tana River for their fresh water.

TNC and partners established the water fund in 2014 to address deteriorating water quality and quantity in the Tana River, which supplies 95 percent of Nairobi’s freshwater supply and 40% of Kenya’s hydropower. The fund was also designed to help improve the livelihoods of farmers living upstream within the Tana watershed through the implementation of sustainable farming practices. As of August 2021, 44,725 farmers have fully implemented conservation activities, 3.4million trees have been planted, 163 hectares of public forest rehabilitated, and 298 kilometers of riparian buffer lands fully conserved.

The Tana River

The Tana River supplies 95 percent of the water for Nairobi’s 4 million residents, and for another 5 million people living in the watershed. It also feeds one of the country’s most important agricultural areas and provides half of the country’s hydropower output. With Nairobi contributing 60 percent of the country’s GDP, the Tana River truly fuels Kenya’s economic growth.

Since the 1970s, forests on steep hillsides and areas of wetlands have been converted to agriculture, removing natural areas for storing runoff water and soil from the land. Now, as rain falls over farms, soils are washed down into the river, which reduces the productivity of farmland and sends sediment into the rivers. This increased sedimentation can choke water treatment and distribution facilities causing complete service disruptions for days or weeks at a time.

Tana River © Ron Geatz

Today, 60 percent of Nairobi’s residents do not have access to a reliable water supply.

This growing challenge requires something innovative to protect the Tana River, increase downstream water quality and quantity and provide positive benefits for tens of thousands of farmers in the watershed. Enter the Upper Tana-Nairobi Water Fund. Water funds are founded on the principle that it is cheaper to prevent water problems at the source than it is to address them further downstream. Public and private donors and major water consumers downstream contribute to the Fund to support upstream water and soil conservation measures, resulting in improved water quality and supply.

Building on TNC's experience with more than 40 water funds around the world, the Upper Tana-Nairobi Water Fund now serves as a model for new water conservation efforts across Africa.

Investing in Nature to Secure Water

The Water Fund is seen as a sound investment by utilities and companies who rely on the Tana River. In fact, the fund’s business case showed that a $10 million USD investment in water fund-led conservation interventions is likely to return $21.5 million USD in economic benefits over a 30-year timeframe. Learn more below.


Within the Upper Tana-Nairobi Water Fund, TNC is experimenting with incentives to get thousands of farmers to adopt agricultural practices that reduce erosion across Kenya’s Tana River watershed. By working with partners to install water pans that capture rainwater and keep that water from washing away the earth, soil fertility is also increasing which greatly benefits the farmers.

Read the full "Experimenting with Water Funds + Behavior Change" article on The Nature Conservancy's Cool Green Science Blog site here.

Staff of The Nature Conservancy and the Upper Tana Nairobi Water Fund collecting soil samples from a tomato plot with the farmer. The farmer is using water from water pans—an erosion control measure that improves water security—to irrigate crops like tomato that have higher market value. Photo Credit: Irene Muthuka

Certificate example of a soil health status card provided to a farmer in Muranga County within the Upper-Tanna Nairobi watershed.

Download the PPT slide

Read the 2-page summary of the nutrient maps and soil health interventions that took place in the Upper Tana Nairobi Water Fund: CLICK HERE

factsheets & guides - Water Pans and Soil

Explore Further

Visit THE ROLE OF SOIL page on the Toolbox for additional resources and information.

Additional Publications & Resources - Nairobi Water Fund


1-pager case study document about the Upper Tana-Nairobi Water Fund in Kenya (available in English, Spanish, Portuguese and French)