Water levels in Hukou Waterfalls have been rising due to rising temperatures and reservoir water release. Hukou Waterfalls, the world's only yellow waterfall, sit at the intersection of China's north and northwestern Shanxi and Shaanxi provinces. It gets its yellow color from sediments in the Yellow River. Environmental cleanup efforts have made the water clearer with less sand and mud. On May 19, visitors to the Shanxi Hukou Waterfalls Scenic Spot can enjoy half-price tickets in celebration of China Tourism Day.