By Michael Ouma

NAIROBI, Kenya – Daybreak and dusk are scary times for the families farming small patches of land near the water treatment plant just outside this East African capital.

The problem is hippos – huge, leathery beasts that come snorting out of the darkness like army tanks, trampling people, smashing cars and uprooting crops.

“I can not even dare enjoy my evening drink with friends because of the hippos,” said Franklin Mwiti, who moved to the area, known as Ruai, four years ago. “One resident was recently attacked by the animals while coming home.”

This is as much a story about dirty water as about hippos tromping around a once-quiet neighbourhood.

For as long as anyone can remember, the hippos congregated in the shallows of the Nairobi River, some distance from Ruai, which is 12 miles northeast of Nairobi. But for reasons that are not clear, about 20 hippos have migrated closer to the Ruai area. They now spend most of their time in the more than 30 shallow ponds created when the government built the Dandora Sewage Treatment Plant. 

Security workers at the Sewage Treatment plant say it seems obvious why the hippos moved. “The hippos must have considered the river to be too contaminated,” said John Ochieng, one of the treatment plant guards.

But Lekishon Kenana, the senior research scientists in charge of the Kenya Wildlife Service in the area, said the hippos may have moved to be closer to the food available at the small farms and may have felt more comfortable in the less turbulent waters of the spacious ponds. The ponds are about 100 yards wide and about 200 yards long compared to the narrow Nairobi River with its equally narrow banks.

Mr. Kenana said the hippos do not seem to mind muddy or waste-filled water. “If hippos avoided pollution or contamination you would expect them to be localized in the cleaner ponds,” he said. “This is however not the situation. Here we have a group of hippos who consistently stay in the dirty ponds.”

The hippos go looking for food at dawn and dusk and that has changed life in the area. “People have since become cautious of moving around here, especially in the wee hours of the morning and at night,”Mr. Ochieng said.

The first settlers in the area were squatters. But, eventually, the government gave many of them one-acre plots on the edge of the ponds. The former squatters use water treated at the plant to irrigate their fields of kale, spinach, carrots and corn, known here as maize.

But the people of Ruai say that the water from the treatment plant is not fit to drink and that they buy water at high prices every day from vendors pulling hand carts.  The Nairobi City Water and Sewerage Company pipes more affordable water to Ruai. But most of the one-room houses are not connected to the municipal water line.  

As for the hippos, people in the area say they have asked the Kenya Wildlife Service to move the animals to a place where they will not cause trouble for humans. But they say the agency has not helped them.

Mr. Kenana said his agency “has made numerous efforts to address” the hippo problem. The agency, he said, considered relocating the hippos. But he said the consensus was that they would probably just meander back to the sewage ponds. Now, he said, the agency is considering building hippo barriers to protect the people and their crops.

Complicating matters for the agency, the hippos are now considered an endangered species. They are listed as vulnerable by the International Conservation Union, Mr. Kenana said, adding that 90 per cent of the hippos in the nearby country of Congo have been killed.

So, for now at least, the Mwitis and other families in Ruai can only stay alert and hope that the hippos do not visit. They worry not only about their safety but about their financial security.  “The hippos come and wreck havoc on our plots, forcing us to replant,” Mr. Mwitis said. “Then we have to purchase seeds a second time.”