According to what I've read, and  I don't claim to know everything about the situation, the Hammonds and nearly 100 other ranchers bought large tracts of land back in the late 50's, which included water rights and grazing rights. The ranchers built irrigation systems and turned the area into a plush fertile paradise. Then, starting in 1961 the government started their strongarm tactics to drive off the landowners so they could seize the land.  They destroyed the irrigation systems, turning the land into a dustbowl, which drove off a vast majority of ranchers... Hammonds and Bundys are a little more stubborn, it seems... so now the government has restorted to shooting them, from all accounts....