 The central, or middle, route runs from Danjiangkou Reservoir on the Han river, a tributary of the Yangtze River, to Beijing.This project involved raising the height of the Danjiangkou dam by increasing the dam crest elevation from 162 m to 176.6 m above the sea level.This addition to the dam's height allowed the water level in the reservoir to rise from 157m to 170 m above the sea level.