Environment Cabinet secretary Keriako Tobiko has directed the National Environmental Management Authority (NEMA) to urgently begin cracking the whip on all corporates, individuals, and entities polluting water sources and wetland areas in the country. He lamented that the Sabaki River, which begins at Ontiri Swamp and changes names to Ngong, Nairobi, Athi, Galana, and Sabaki as it flows towards the Indian Ocean, had suffered serious pollution and immediate remedial measures should be taken to stop the menace.