AbstractWith a focus by scholars on states and classes, the environment of India and its impact on agriculture has been neglected, except to provide a context—which was largely unchanging—in which states extracted and classes struggled. One example of environment as the backdrop is the distinction between ‘wet’ and ‘dry’ areas in Tamilnad and South India more widely. This distinction is based on the availability of water and on the local categorization of agricultural activity (nanjai versus punjai). There are two problems with this approach, however. First, it is a narrow treatment of the environment as it neglects other features of the land such as forests, grasslands, scrublands, and other so-called wasteland. Second, it sees the environment as a fixed entity, but the landscape has changed dramatically in the past, especially in the nineteenth and twentieth centuries. If changes in the environment are included in the mix, the development of agriculture in nineteenth-century Tamilnad may be seen in some new ways. Agricultural production existed in symbiosis with the complex and varied environment of the region. In the early nineteenth century Tamilnad contained extensive tracts of forests, widespread wastelands, and abundant surface water. This diverse environment made it possible to maintain high levels of agricultural productivity as it provided the resources to maintain the fertility of the soil and the supplies of water that were critical for agricultural enterprise, as well as the well-being of the rural population. The consequences of changing regimes of water is the focus of this article.