Taos valley acequias community-based irrigation system, Taos, New Mexico, USA

Key findings: The Taos valley acequias have survived for several hundred years as a community-based irrigation system due to a mix of social and biophysical features. These include:

A low-cost decentralized monitoring system that is enabled by both water distribution institutions and the geographic location of users Multiple levels of governance built up by key actors within each acequia A system of shallow groundwater aquifers which are particularly important during droughts, and which are naturally replenished due to the unlined earthen canal the acequias use to irrigate

Summary: An acequia is a community of irrigating farmers. The acequias in New Mexico and in parts of southern Colorado are the descendants of the original Spanish colonists who moved north along the Rio Grande from Mexico beginning around 1600.  The majority of the traditionally functioning acequias in New Mexico are its northern half, which is more mountainous and therefore receives more water.  The study area for this analysis is in Taos valley in Taos County, one of the northern-most counties in New Mexico.   Each has a well-defined governance structure, led by a mayordomo and three commissioners.  The mayordomo is in charge of deciding how the water is distributed within his or her acequia, and is the primary monitor and enforcer of infractions.  The commissioners serve a variety of administrative, legislative, and judicial roles within their acequia.  They are frequently called on to arbitrate disputes and support the mayordomo in enforcing ditch rules.  Water is distributed within each acequia in accordance with a commonly-accepted set of rules, and compliance with community obligations is required in order for an individual to maintain his/her water rights.  Such communal obligations are an important feature of the common property arrangements that typify community-based systems.     The acequias in Taos valley, like acequias around the state, have sustained themselves as self-sufficient irrigation systems for hundreds of years by adapting to high desert conditions and inevitable periods of drought.  They are now facing the threat of economic development, changing demographics, and the penetration of water markets.  This study focuses on their social and biophysical properties that have enabled them to persist in the face of droughts, leaving the question of their robustness, or vulnerability, to modern disturbances to a subsequent paper.