ABSTRACT
In March 2017 the national government of Aotearoa New Zealand passed legislation that established the Whanganui River and its catchment as a legal person. Legal constructivism emphasises the power of the law to construct its subjects, rather than simply finding existing subjects already in the world. Rivers and wetlands are among the most threatened ecological systems in the world. Extraction of water for human use can cut off habitats for fish spawning and bird breeding, and cause the dieback of aquatic vegetation. Healthy rivers and wetlands depend on both water quantity and water quality, but in many catchments high levels of water extraction mean that there is simply not enough water, so water quantity has become the overriding concern. Environmental flows are sometimes called instream flows: water provided for environmental purposes within the river which moves through the system and may be available for alternative uses downstream. Water law is often rather vague when it comes to defining aquatic ecosystems.
