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Clean water for people–and mangroves–on a Kenyan island

August 25, 2020

Driving north from Mombasa on Kenya’s main coastal highway, the dense city traffic gives way to rolling hills, expansive farms, baobab trees, and the occasional roadside produce stand or open-air market. At the popular seaside destination of Malindi, the winding road features stunning views of the Indian Ocean. But a few miles further north, something else starts to dominate the landscape: the salt industry.

Approaching the town of Marereni, salt ponds, evaporating huge quantities of seawater to extract valuable minerals, stretch as far as the eye can see. Refineries belch black smoke from rusty stacks as they burn impurities out of the salt. Piles of unrefined salt, nearly as tall as the processing buildings, sit alongside the ponds. Large dikes built to separate the salt ponds from the sea have interrupted natural flows of water and turned former marshland into dry, barren industrial zones.

For years, these facilities operated with little concern for local communities or the sensitive environment upon which they were built. In Marereni, brine left over from the refining process was pumped back into the coastal waters, with devastating consequences. The area’s mangroves — despite their tolerance for the salt in ordinary seawater — were poisoned. The brine contaminated groundwater and left wells unusable.

A lawsuit stopped local salt manufacturers from dumping high-salinity water into the estuary.

About a thousand people live on Giriama Island, cut off from the mainland's infrastructure.

The people of Marereni and surrounding communities had had enough. They sued the local salt manufacturer and won a court order to stop the dumping of brine. The ecosystem began to heal, but people still couldn’t get enough fresh water. The mangroves, essential habitat for the fish that support the local economy, were severely degraded.

To help the area’s ecosystems and communities recover from the decades of abuse, Seacology began working with the Marereni Beach Management Unit (BMU), the local government body responsible for managing marine resources. Our project, launched in 2019, funded equipment that helps the BMU protect the nearly 200 acres of remaining mangroves around Giriama (also known as Robinson) Island, just offshore from Marereni.

It also funded thousands of mangrove seedlings, which dozens of volunteers from the community planted in areas damaged by industrial pollution. A recent survey showed that the newly planted mangrove seedlings have a survival rate of 90% – an impressive figure even under ideal conditions.

Giriama Island community members replant mangroves.

Thousands of mangrove seedlings were planted around Giriama Island.

Despite the severe damage to the coastal ecosystem, its recovery has been remarkable. With the dumping halted, clean water has flushed the excess salt out of the estuary, and the water chemistry has mostly returned to its natural state.

Giriama Island, home to about 1,000 people, has no plumbing or electrical grid. It is separated from Marereni by sprawling salt ponds, a maze of industrial access roads, and a dense, formerly polluted estuary. The bridge that once connected it to the mainland collapsed, so people can get to and from the island only by small boats. Seacology funded construction of a 66,000-gallon water cistern to store rainwater on the island. The cistern was completed earlier this year and filled by heavy rains, bolstering water security for the community and relieving them of the burden and cost of importing water from Mareneni.

The project was made possible by generous support from 11th Hour Racing, a Rhode Island-based organization that advances innovative projects and collaborative, systemic change to improve the health of our ocean and address the dynamic environmental challenges facing the sailing and marine communities.

Members of the Giriama Island community build the cistern.

BMU representatives and Giriama residents inspect the finished cistern.