A major breadbasket of colonial Mexico, the Bajío has attracted substantial scholarly interest in recent years. Michael Murphy’s compact but carefully detailed study of colonial water use provides a useful technical supplement to this scholarship. Based largely on sources in the Tierras and Mercedes sections of the Archivo General de la Nación in Mexico City, the book includes four subregional studies tracing the building and operation of local irrigation systems in Celaya, Salvatierra, Salamanca, and Querétaro, followed by thematic chapters on agriculture, technology, and water law. The author also analyzes the development of city water systems in Celaya and Querétaro.

The ecology and economics of colonial agriculture made irrigation important in the Bajío. Although only Indian subsistence farmers had incentives to intensify cultivation through irrigated double-cropping, hacendados found that irrigation enabled them to produce wheat during the dry winter months and thereby avoid fungal infestations and other hazards of the rainy season. Subject therefore to meteorological cycles different from those of maize, wheat offered a welcome means of diversification and a consequent hedge against crop failure. Moreover, since subsistence farmers produced little wheat, the crop did not experience the destabilizing shifts in supply and price that characterized colonial markets in maize.

Although members of the landowning local elite took most of the initiative in allocating water among competing users, “sporadic interventions of central authority” (p. 200) invoked the protective features of colonial law and shielded smaller claimants from blatant usurpation of their water rights. Except when they needed to safeguard city water supplies, municipal authorities played relatively minor roles in regulating water use.

In his chapter on irrigation technology, Murphy acknowledges that for much of the colonial period Mexicans lagged far behind their European contemporaries. By the early nineteenth century, however, they had made significant progress in closing the gap. Murphy concludes that Alexander von Humboldt seriously underestimated the technical and architectural expertise evident in late colonial water systems of the Bajío. Enhanced by present-day photographs of surviving irrigation works and helpful explanatory drawings that accompany the reproductions of colonial maps, Murphy’s book provides a solid contribution to our knowledge of the colonial Bajío.