Water rights

Water right in water law refers to the right of a user to use water from a water source, e.g., a river, stream, pond or source of groundwater. In areas with plentiful water and few users, such systems are generally not complicated or contentious. In other areas, especially arid areas where irrigation is practiced, such systems are often the source of conflict, both legal and physical. Some systems treat surface water and ground water in the same manner, while others use different principles for each.

Fundamental differences exist between the nature and source of water rights in different countries. Generally, water rights are based on the water law that applies in a particular country and, at their most basic, are classified as land-based or use-based rights.

Some countries allow their subdivisions to establish independent water laws. For example, each state and territory of the United States has its own set of water laws that establish water rights that may be land-based, use-based, or both.

Some water rights are based on land ownership or possession. For example, many common law jurisdictions recognize riparian rights, which are protected by property law. Riparian rights state that only the owner of the banks of the water source have a right to the 'undiminished, unaltered flow' of the water.

In Finland, waterbodies are generally privately owned, which is not the case in most EU countries, but Finland also applies the Roman law principle of aqua profluens (flowing water), according to which the freely flowing water in waterbodies cannot be owned or possessed. This means that the owners of waterbodies cannot prohibit diversion of water for agricultural, industrial, municipal, or domestic use according to the provisions of the Finnish Water Law and cannot prohibit use of the waterbodies for recreational purposes.

In some jurisdictions water rights are granted directly to communities and water is reserved to provide sufficient capacity for the future growth of that particular community. For example, California provides communities and other water users within watersheds senior status over appropriative (use-based) water rights solely because they are located where the water originates and naturally flows. A second example of community-based water rights is pueblo water rights. As recognized by California, pueblo water rights are grants to individual settlements (i.e. pueblos) over all streams and rivers flowing through the city and to all groundwater aquifers underlying that particular city. The pueblo's claim expands with the needs of the city and may be used to supply the needs of areas that are later annexed to the city. While California recognizes pueblo water rights, pueblo water rights are controversial. Some modern scholars and courts argue that the pueblo water rights doctrine lacks a historical basis in Spanish or Mexican water law.

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