Ansal grabbed a makeshift raincoat, an empty rice sack, and ran home as the rain began to pound the fields of Pomalaa. A few hours later, after the rain stopped, the 49-year-old returned to his fields.

“Everything is red,” Ansal told Mongabay Indonesia, here in Kolaka district in the province of Southeast Sulawesi.

In previous years, the occasional floods were more manageable, but this downpour caused the river to burst its banks. The ensuing overflow caked Ansal’s field in a layer of knee-deep sludge, drowning the newly planted rice under water the color of clay.

Red mud is typically seen near mining sites as a byproduct of the Bayer process, a chemical reaction used to extract aluminum compounds from bauxite ores. In nickel mining, a process known as high-pressure acid leaching separates nickel from its ores at high temperatures. Waste from nickel mining includes oxidized iron, which gives the waste its bloody tint.

A study conducted in the Philippines and published in February in the Journal of Environmental Chemical Engineering found that one of the greatest challenges in nickel mining was the “siltation of streams, rivers and estuaries, which has negative impacts to farming and fishing communities living close to the mine sites.”

ForSDA, a local civil society organization, recorded that the flooding inundated 650 hectares (1,600 acres) of rice fields across three villages in Kolaka’s Pomalaa subdistrict. Pesouha village was by far the worst affected, accounting for around 500 hectares (1,240 acres) of submerged land.