"The Dandora Oxygenation Ponds are situated 20 km due east of Nairobi City centre, just off the Nairobi–Kangundo road but within the city limits. The main sewage treatment works for Nairobi City, they comprise three experimental ponds, eight facultation ponds and 24 maturation ponds...."
Lakes 
"The Dandora Oxygenation Ponds are situated 20 km due east of Nairobi City centre, just off the Nairobi–Kangundo road but within the city limits. The main sewage treatment works for Nairobi City, they comprise three experimental ponds, eight facultation ponds and 24 maturation ponds...."
That's gotta be it.