It’s been a busy two months for PRESA and its partners at the Sasumua site as water and soil sampling activities get underway.

This month a team from ICRAF and the Jomo Kenyatta University of Agriculture and Technology was at the Sasumua Dam catchment collecting water samples for evidence of chemical and biological contamination.

Jomo Kenyatta University scientists collecting water samples at Sasumua.

Located about 100 kilometres north of the Kenyan capital, Nairobi, the lower reaches of the Aberdare Mountain forest provide fresh water to the city. Most of this water is collected from the forest and surrounding farmlands, and held in a series of dams, including the Sasumua, Ruiru and Ndakaini.

October’s water testing activity closely followed a soil sampling exercise in September. A team consisting of ICRAF researcher Tor Gunnar-Vagen and PRESA geo-spatial analyst, Miika Makela was familiarizing with a new soil sampling protocol. The new protocol is expected to become an Africa-wide standard for collecting soil and land use data.

The soil sampling was done by members of the local community in Njabini. Participants performed quite well after they were taught what to do in just a matter of hours. “This is the best way of sensitizing people to our efforts, getting them really hands-on involved in the research,” says Miika.

Main challenges with watersheds in Kenya

Until now, issues of water quality and allocation have been problematic, resulting in discontent and mistrust. There are strong inequities between rural and urban areas. Conflict is frequently related to the changing use of land and other natural resources: deforestation, charcoal burning, creation of new settlements and marijuana cultivation in the Aberdares watershed.

The ‘shamba’ system - which allows agriculture in forests - best reflects the political, social and equity dimensions of Kenya’s unpredictable policy context. The ‘shamba’ system was introduced in the early 1900s to obtain cheap labor from neighbouring communities for forest plantations. However, it eventually became a conduit for allocating forest land to politicians. As a result, farmers deliberately manipulated the performance of planted seedlings, either by de-barking or cutting the roots of saplings to ensure continued tenancy on the land for subsistence crop production.

Run-off from a construction site polluting Nairobi's water supply.

Farmer communities adjacent to water reservoirs neither obtain high quality drinking water nor electricity from the facilities. They are neither recognized nor compensated for the important services their land generates for distant users and therefore see no economic reason to modify their land use decisions. This has implications on the number of people who have access to safe drinking water both in rural communities and within squatter settlements in urban areas.

Thus, current frameworks of policy and legislation have not been successful in resolving the conflicting interests involved. We therefore see pro-poor market based approaches, such as PRESA, as a better option.

Why PRESA selected the Sasumua site

As far as rewards for environmental services are concerned, linking the Sasumua dam with Nairobi’s water supply has significant potential for support because the beneficiaries are easy to identify; they are already organized, already have some payment mechanisms and are receiving well-defined benefits. It is for these factors that the Sasumua catchment was selected as a PRESA site.

The Sasumua Water Treatment Plant near Njabini Township is operated by the Nairobi Water and Sewerage Company. This plant, by itself, supplies about 20 percent of Nairobi’s potable water supply. It draws its water from three rivers: the Sasumua River, the Chania River, and the Kiburu River.

Preliminary studies indicate that the Nairobi City Water and Sewerage Company spends approximately 10million shillings a year (approx US$ 127,000) in removing silt from clogged water intakes and for water purification. The major pollutants are soil, crop residues, animal droppings and runoff from petroleum sale outlets.

Pollution and siltation results in higher bacterial count, abnormal acidity levels in water, dirty water and increase in chemicals from pesticides and fertilizers. Pollution from the small towns of Haraka and Njabini together with surrounding agricultural areas is more important at Sasumua than the effects of forest degradation.

Building a community of practice

The Jomo Kenyatta University and ICRAF team collected samples of water along the Small Sasumua River, the Big Sasumua River, the Chania River outlet into the Sasumua Reservoir and the Chania River as it flows through Njabini Township. More samples of water were collected where the Kiburu River feeds the Sasumua reservoir. The team went to the bed of the near-empty reservoir to collect samples at selected points.

Tor Gunnar-Vagen (left) with farmers in the Sasumua water catchment.

In September, Miika Makela of PRESA and ICRAF researcher Tor Gunnar-Vagen were collecting soil samples from farms within the catchment. The two were practicing a soil sampling protocol developed by Tor and ICRAF soil scientist, Keith Shepherd. This protocol is being implemented in various regions in Africa with the objective of building a soil database.

“The data collected in Sasumua will benefit ICRAF and Jomo Kenyatta University’s efforts in the catchment, but more importantly it will be a part of a growing database which will enable interesting work to be done for years to come,” explains Miika.

With collaboration being a vital component in building a PRESA community of practice, data analysis for the soil and water sampling work has been split between two organizations: ICRAF has employed its equipment in soil sample analysis while Jomo Kenyatta University is scrutinizing water samples at laboratories within its main campus.