This video was shot earlier this month by M. Sanjayan, a scientist at The Nature Conservancy, who spotted a giant wall of foam engulfing the road on his way to work one day.
Sanjayan describes what he saw in the Huffington Post:
I was on my way to my first appointment but halfway through my journey, not far from the Kenya Wildlife Service headquarters, when the road I was on was blocked by a wall of suds, white and fluffy as if spewing out of an errant giant steam carpet cleaner, was slowly swallowing the four-lane highway before me. This soapy surge was well over two stories high in places. It rose from the fast-flowing creek that runs below the road, whose waters were now a mounting froth spilling over the banks. The air smelled of chemicals. My eyes watered and in my mouth I tasted a residue of a suds . . . I later found out that this suds-engulfed creek flows right through Nairobi's biggest slum, Kibera, where tens of thousands of people depend on the waterway for a host of daily needs. The creek itself eventually filters through a national park filled with hippos, crocs, buffalo and lions. The clouds of white froth I had witnessed were probably caused by a mix of phosphate run-off (fertilizer and sanitation waste), detergents and industrial effluents in the stream whipped up by the rainstorm. And a little research shows that it happens all the time in streams across the world — from Canada to Indonesia.
Learn more, and see more pictures of the foam flood, over at HuffPo.