Water rights:

1.Two major doctrines: for determining the allocation of water in water-courses, such as streams, rivers, and lakes:
– riparian doctrine: water belongs to those who own the land bordering the water course; those people are known as riparians, who share the right of reasonable use of the water; one riparian is liable to another if his or her use unreasonably interferes with other’s use; domestic use trumps commercial and can be unlimited
– prior appropriation: the water belongs initially to the state, but the right to divert it and use it can be acquired by an individual, regardless of whether or not he happens to be a riparian owner; rights are determined by priority of beneficial use; the norm for allocation is first in time, first in right; any productive or beneficial use of the water, including use for agriculture is sufficient to create the appropriation right

2. Percolating water (groundwater): water beneath the surface of the earth that is not confined to a known channel; surface owner entitled to make reasonable use of groundwater but such use must not be wasteful

3. Surface water: common enemy rule (followed by ½ the states): landowner may change drainage or make any other changes/improvements on  his land to combat the flow of surface water; many courts have modified rule to prohibit unnecessary harm to other’s land