Riparian water rights (or simply riparian rights) is a system for allocating water among those who possess land along its path. It has its origins in English common law. Riparian water rights exist in many jurisdictions with a common law heritage, such as Canada, Australia, and states in the eastern United States.
Common land ownership can be organized into a partition unit, a corporation consisting of the landowners on the shore that formally owns the water area and determines its use.
Under the riparian principle, all landowners whose properties adjoin a body of water have the right to make reasonable use of it as it flows through or over their properties. If there is not enough water to satisfy all users, allotments are generally fixed in proportion to frontage on the water source. These rights cannot be sold or transferred other than with the adjoining land and only in reasonable quantities associated with that land. The water cannot be transferred out of the watershed without due consideration as to the rights of the downstream riparian landowners.
Riparian rights include such things as the right to access for swimming, boating and fishing; the right to wharf out to a point of navigability; the right to erect structures such as docks, piers, and boat lifts; the right to use the water for domestic purposes; the right to accretions caused by water level fluctuations; the right to exclusive use if the waterbody is non-navigable. Riparian rights also depend upon "reasonable use" as it relates to other riparian owners to ensure that the rights of one riparian owner are weighed fairly and equitably with the rights of adjacent riparian owners.
The Environment Agency lists the riparian rights and duties in England and Wales: The rights include ownership of the land up to the centre of the watercourse unless it is known to be owned by someone else, the right for water to flow onto land in its natural quantity and quality, the right to protect property from flooding and land from erosion but subject to approval by the agency), the right to fish in the watercourse unless the right is sold or leased if an angler has a valid Environment Agency rod licence. They also include the right to acquire accretion and the right to boomage (a fee charge for securing a boom, generally for the retention of logs).