We welcome the development of Xi’an — China’s former capital and the original eastern end of the Silk Road — into a high-tech city at the heart of the country’s 2013 Belt and Road Initiative for worldwide trade (Nature 563, S25–S27; 2018). However, it is crucial that the ambitious infrastructure planning includes provisions to protect the city’s environment from further degradation.

The nearby Qinling Mountains provide 90% of the drinking water for the 10 million or so residents of Xi’an. The range hosts 4,000 plant and animal species, and contains 15 natural and cultural heritage sites of ancient civilizations going back 5,000 years to the Xia dynasty. Developing China’s ‘silicon valley’ so close to these mountains could seriously disrupt the ecosystem (S. Thacker et al. Nature Sustain. 2, 324–331; 2019).

Xi’an is already one of China’s most polluted cities, with many outdated coal-burning factories. Only half of the city’s 15 rivers are classified as clean. The daily discharge of domestic sewage into these rivers can reach 8,000 tonnes. The Zao River, which crosses the city’s Hi-tech Industries Development Zone, is black and malodorous.

All these issues need to be addressed before major changes associated with the development go ahead (see, for example, L. Han et al. Sci. Rep. 6, 23604; 2016).