- Our sampling points were Ondiri springs in Kikuyu, Ndwaru, or Satellite, near Kawangware and Chiromo at the Museum Hill interchange near the Nairobi Museum.
- We tested for the presence of 12 different metals of toxicological importance using the East African standard known as procedure 67.
The two-month river pollution investigative project, “Toxic Flow”, started with mapping out the entire river and breaking it down into sections depending on the intensity of human activity.
We spent days researching the tributaries through its 390-kilometre journey as it traverses several counties to the Kenyan coast.
We trailed the river from Kiambu County where it starts, through Nairobi, Machakos, Makueni, Taita Taveta and Kilifi counties, until it exited into the Indian Ocean at Sabaki Bridge.
A team of scientists from the University of Nairobi helped us narrow down our investigation by selecting 10 sampling points on the river, which tells its whole story.
From these points, we collected 49 samples comprising water, sediments, fish, vegetables, crabs and other aquatic animals.
The sampling points represented the major anthropogenic activities along the river, mainly agricultural and industrial.
Our sampling points were Ondiri springs in Kikuyu, Ndwaru or Satellite near Kawangware and Chiromo at the Museum Hill interchange near the Nairobi Museum.
The other points were Gikomba, Dandora dumpsite, and Pipeline near the bridge on Outer Ring road.
The next sample was picked at Thwake Makueni County, from where the river is being diverted to harvest water for the Sh82 billion dam.
The last two points were in Malindi near Sabaki Bridge, where the river ends.
As we picked the samples, we recorded the exact GPS coordinates of every sampling point using a smart phone.
We picked four water samples at each of the 10 sampling points to make the sample collection watertight.