People dig into a dry riverbed in Kasengela village, Kenya. The sound of shovels echoes through the valley. Workers mix cement and sand to make concrete. Other workers carry rocks.

They are building a sand dam. The structure harvests water from seasonal rivers. A barrier, typically made of concrete, slows water flow. Sand settles behind it. That creates an artificial aquifer that fills up during rainy seasons. (An aquifer is an underground spot that holds water.) People dig in the sand or use hand pumps to collect water.

The southeastern region of Kenya is dry. There aren’t many permanent rivers or wells in the area. Building sand dams on the seasonal rivers keeps some of the water underground. Less of it evaporates. That also refills groundwater.

Rhoda Peter lives in Kyalika village in Makueni County. She worked with a group to build three sand dams along a nearby river.

“When I think about sand dams, I feel happy,” says Ms. Peter. “Our shallow well does not dry. It goes all through the dry seasons.”

Before the dams were built, she and her children had to walk three hours to get water.

Without clean water, diseases spread. Children travel long distances for water instead of going to school. Livestock and crops die.

In Kasengela, Mwanzia Mutua leads the group building the dam. He says that he used to trek more than four miles from his home to the Athi River to fetch water for his household and animals. The trip there and back took an entire day. The sand dam will shorten the walk to get water to 10 minutes, he says.

“When water is far, you spend all your time looking for it and are unable to do any other work,” says the farmer. “Cattle die because the water is far.”

The sand dam in Kasengela was completed on March 14. It took two and a half months to build. It should be ready to use by December 2025 after it fills with sand.

With joy you will draw water from the wells of salvation. — Isaiah 12:3