Lanzhou as one of China's most important industrial cities grows is heavily dependent on the Yellow River. For years this city was considered the most polluted city on Earth. To save its reputation and improve the health of its river it has tried to clean up its local environment. Given that this water is flowing through much of Northern China a city by city approach to improving its water conditions and supplies is doing little to improve its future. In an attempt to save this river several pipelines have been built to replenish this river by diverting some of the flow of the Yangtze River.