Rising Waters Swamp Lake Naivasha

Kenya’s Lake Naivasha has long been a place of change and reinvention.

In precolonial times, the nomadic Maasai people used the lake and surrounding grasslands to water and raise cattle during the dry season. The Maasai were eventually displaced by British colonists in the late 19th and early 20th centuries, including a group of free-thinking aristocrats who arrived in large numbers in the 1920s through 1940s. Known as the Happy Valley set, these newcomers cultivated lavish estates and were notorious for reveling in a culture of excess. Their influence faded in the 1950s and 1960s amid scandal and the overthrow of colonial rule, allowing the area to transform into a center of wildlife tourism, flower farming, and geothermal energy production.

Now the lake faces another major change: rapidly fluctuating water levels. The name Naivasha comes from a Maasai word meaning “that which heaves,” an apt description of the freshwater lake over the past 25 years. Satellite altimetry measurements of the lake’s depth indicate an increase of about 7 meters (23 feet) since 2010, roughly the height of a two-story building. Over the same period, Landsat observed a roughly 40 percent increase in the lake’s area, adding 50 square kilometers (19 square miles) of water, equivalent to roughly 15 Central Parks.

The human and economic toll of the rising water levels is considerable, said Mathew Herrnegger, a hydrologist at BOKU University in Vienna, Austria. Homes, flower farms, and roads along the shores have all flooded in recent years, displacing large numbers of people. Lake Oloidien, once a separate lake, has effectively merged with Naivasha, bringing an influx of saline, alkaline water to Naivasha’s freshwater system.

The Landsat images above compare the same area in January 2010 (left) and January 2026 (right), illustrating the scope of the changes. Neighborhoods in the southwestern part of the town of Naivasha have been particularly hard hit. Flooding has been widespread in the neighborhood of Kihoto, with entire town blocks inundated, including police stations, churches, hotels, restaurants, electrical power substations, and sewer systems.

“Increased rainfall is the primary driver,” Herrnegger said. Mean annual rainfall rose by about 30 percent between 2010 and 2020 compared to the preceding decade, with a 318 percent increase in high-intensity rainfall, he said. Because the lake lies in a closed basin and has no surface outflow, it is especially sensitive to even modest changes in the water balance. Herrnegger and colleagues estimate that a 0.4–2.0 percent increase in annual rainfall is sufficient to explain the dramatic rises. “It is a system that, once tipped, responds strongly,” he said.

The flower industry around the lake, which produces hundreds of millions of dollars in exports per year, is losing greenhouses, farmland, packing sheds, and worker housing on a significant scale. In communities such as Sulmac Village, Karagita, and Kasarani, many greenhouses that just a decade ago were set back a kilometer or more from the water now have lakeshore views.

Crescent Island—once a peninsula along the lake’s southern shore near several former Happy Valley estates and country clubs—is now primarily a game sanctuary and wildlife tourism destination. Hundreds of hippos live in the lake, and people, especially commercial fishermen, are encountering them with more frequency as waters rise.

The images also show the expansion of aquatic vegetation, especially water hyacinth. Remote sensing scientists and journalists have documented a rapid proliferation of the plant over the past two decades, which has interfered with fishing and tourism and possibly contributed to the lake’s rising water levels by slowing evaporation.

Other researchers have pointed to tectonic influences changing the rate of groundwater recharge into the lake as a possible contributing factor. In addition, the accumulation of sediment may be filling shallow areas and reshaping the lake floor such that water levels may be rising and increasing the lake extent even though the volume of water held by the lake may be unchanged, explained Jamie Shutler, a professor of earth and environmental science at the University of Exeter in England.

“Given the large number of people who rely on this lake for food and their livelihoods, the change we’re seeing from the satellite imagery combined with the stories of displacement is alarming,” Shutler said. “We need more research to assess exactly how much the volume of water is changing each year and why.”

NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the U.S. Geological Survey and water level data from Global Water Measurements. Story by Adam Voiland.