In addition, we have described and implemented a novel, replicable methodology for producing an unbiased estimate of the water pollution-health dose-response function leveraging the flow of rivers.

Our reduced-form estimate of the relationship between environmental quality and health mirrors those of Ebenstein (2012) and Brainerd and Menon (2014) and indicates that the costs of river pollution are significant.<sup>18</sup> The latter authors’ findings are particularly consistent with our own results, in that they, too, specifically show neonatal mortality to be affected by water pollution in India. Given widespread breastfeeding practices in India, these results suggest that alternative modes of contamination other than drinking river water – such as bathing and person-to-person transmission – are at work (Cifuentes et al. 2000). Alternatively, pollution exposure _in utero_ may explain our neonatal mortality estimates. While we have limited ability to investigate the timing of pollution exposure, our policy analysis suggests that infants whose gestation periods fall fully after the verdicts have a better probability of survival.

In spite of the harms of pollution, environmental quality remains low in many developing countries. Air quality in Delhi, India, for example, averaged 128 _μ_ g/m<sup>3</sup> of fine particulate matter (PM2.5) in 2015 **–** ten times more than in Washington D.C. ( _Washington Post_ 2016) and significantly _worse_ than in 2010. In that same five-year period, the number of classified ’polluted river stretches’ in India doubled from 150 to 302, and the gap between sewage load and sewage treatment capacity expanded ( _Daily Mail_ 2015). Why, if pollution is so costly, does it persist at high levels?

One explanation is a high marginal utility of consumption (see Greenstone and Jack 2015), which could make the private opportunity cost of pollution reduction greater than the private benefit. In support of this hypothesis, Hanna and Oliva (2015a) show that when Indian households are randomly made wealthier (through a cash-and-livestock transfer), they choose to consume more energy but not cleaner energy. Relatedly, Greenstone and Hanna (2014) argue that, in India, air pollution policy has been more effective than water pollution policy because of relatively greater demand for air quality than for water quality. In our context, Kanpur Nagar district had BOD levels that placed it in the 63rd percentile of Ganga Basin water quality prior to the Supreme Court rulings. Higher pollution levels may, in principle, be associated with larger willingness-to-pay for environmental quality, but our qualitative investigations suggest that demand for water quality was quite low in Kanpur in the 1980s: there was no local movement to improve water quality at the time of Mehta’s writ petition, but there _was_ significant concern about the economic impacts of regulation in a city that relied heavily on the tanning industry for jobs.<sup>19</sup>

> 18Ebenstein (2012) shows that decreases in Chinese river water quality are associated with rises in adult deaths due to stomach cancer: a one-grade deterioration (from a six-grade scale) predicts a 10 percent rise in stomach-cancer mortality. Brainerd and Menon (2014), meanwhile, find that a 10 percent rise in agricultural pollution into India’s rivers is associated with a 6 percent increase in neonatal mortality.

> 19We conducted a qualitative research study in Kanpur in the winter of 2014. The study consisted of interviews of a large number of stakeholders and informants in the Ganga Pollution Cases. These included government officials,

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