Co., 113 U.S. 9 (1885), was a U.S. Supreme Court case considering whether a dam constructed on privately owned land served a public purpose and whether having the owner of the dam compensate any adjacent landowner was a legal form of eminent domain.

The state of New Hampshire passed a General Mills Act in 1868 which established a permitting process for companies to build dams on non-navigable waterways so long as they compensated any adjacent landowners for flooded property.

Head sued claiming the benefit to the company was not a public purpose and that the Equal Protection Clause was being violated because the rights of a major employer was outweighing those of a smaller landowner.

Justice Horace Gray, delivered the opinion of the court that regulating riparian water rights was clearly within the purview of the state, that similar regulations were used in other states, that similar laws in New Hampshire went back to 1718, and that the remedy for any financial loss showed that due process of law was being preserved.

There were no concurring or dissenting opinions but Justice Samuel Blatchford did not participate in the case.