This article examines two of the major water legal regimes in the
Americas—that of Brazil and the United States. Both countries have
extensive wet and dry regions and both hydro-regimes face a significant
threat from global warming. Brazil, for instance, is home to between
eight and fifteen percent of the world’s fresh water, and its fast-growing
economy and population present major challenges in management and
allocation. The U.S. also faces major water allocation problems resulting
from past settlement policies; unsustainable reclamation projects; and
also fast-growing domestic, industrial and agricultural demand.

In the United States, water has traditionally been perceived as a
renewable and limitless resource, a cultural legacy that has exerted a
powerful influence on the nation’s common law. Similarly, in Brazil, the
notion of water as infinitely abundant drove water policies until the
enactment of the Constitution in 1988. In both countries, however,
hydrological realities have become impossible to ignore. Their respective
laws and jurisprudence have begun shifting toward management and
allocation systems that acknowledge the limited nature of the resource.

This article surveys the two countries’ water regimes, offering a
brief history of their evolution and then focusing on the challenges of the
present. It examines how the notion of a strong private property right
in water is slowly (in the North-American case) and more abruptly (in the Brazilian case) evolving in the face of increased governmental

The article then turns to the challenges of climate change. In
Brazil, policies that fail to take desertification into account may threaten
the country’s energy supply as well as the availability of potable water.
In the United States, ignoring climate change in water management and
allocation policies could significantly increase the existing water scarcity
in the West and exacerbate the growing and already serious water
shortage in the traditionally humid East.