to control the flow of water, and thus providing water for irrigation and so mitigating the drought problem. The livelihood of local people of Hangzhou improved over the following years. Bai Juyi used his leisure time to enjoy the beauty of West Lake, visiting it almost daily. He also ordered the construction of a causeway connecting Broken Bridge with Solitary Hill to allow walking on foot, instead of requiring the services of a boat. He then had willows and other trees along planted along the dyke, making it a beautiful landmark. Afterwards, this causeway was later named "Bai Causeway", in his honor.
In 1089, while another renowned poet Su Shi (Su Dongpo) was the city's governor, he used 200,000 workers to construct a 2.8 km long causeway across the West Lake, which Qing Emperor Qianlong considered particularly attractive in the early morning of the spring time. The lake was once a lagoon tens of thousands of years ago. Silt then blocked the way to the sea and the lake was formed. A drill in the lake-bed in 1975 found the sediment of the sea, which confirmed its origin. Artificial preservation prevented the lake from evolving into a marshland. The Su Causeway built by Su Shi, and the Bai Causeway built by Bai Juyi, a Tang Dynasty poet who was once the governor of Hangzhou, were both built out of mud dredged from the bottom of the lake. The lake is surrounded by hills on the northern and western sides. The Baochu Pagoda sits on the Baoshi Hill to the north of the lake
