An ambitious restoration project is bringing back fish—and fishermen—to the North Aral Sea in Kazakhstan, National Geographic reports. The Aral Sea was once one of the world’s largest freshwater lakes, supplying tens of thousands of tons of fish every year. But after the Soviet Union diverted away rivers for agriculture, the sea became saltier, killing off fish and destroying the fishing industry. Today the lake has split into two and is only a 10th its original size. But freshwater fish are beginning to return, thanks to an $86 million project financed by the World Bank that saw construction of a new dam and dykes. The fishing industry is beginning to thrive again, too, though experts warn that overfishing could undo the good work.