Gold mining is a lifeline for many who live in Madre de Dios, an Amazonian region in southeastern Peru, where poverty is high and jobs are scarce. But the economic development comes at a cost, as it causes deforestation, build up of sediment in rivers, and mercury contamination in nearby watersheds, threatening public health, Indigenous peoples, and the future of the biodiversity hotspot. To stop illegal gold mining activity in the area, the Peruvian government implemented "Operation Mercury," deploying armed forces to the La Pampa region (February 2019 to March 2020). A Dartmouth-led study published in Conservation Letters reports on how the intervention was successful but also had its drawbacks.