Algal blooms have been a problem in the Pengxi River since the Three Gorges Reservoir was built in 2004. A study monitored water quality in the area from 2007 to 2009 and found high levels of total nitrogen and total phosphorus, leading to eutrophication. The situation was worse at Shuangjiang Bridge Ferry compared to Gaoyang and Quma Ferries. Total phosphorus was identified as the main cause of eutrophication, with non-point source pollution being the main contributor in the Pengxi backwater area.