Lisa Swanson, age 15, of Glendale, Ariz., for his question:

WHAT ARE RIPARIAN RIGHTS?

Riparian rights are the legal rights of a landowner whose property borders or forms the bed of a stream or river. Each riparian owner has a right to the flow of water in the stream and to use it reasonably.

An owner's permission is required for any increase or decrease in the flow, any move to change the flow's direction, or any action that would make the water dirty.

The riparian owner may own the land extending to the center of the bed of a stream, or only to the usual high watermark along a navigable stream.

In western states with scarce water supplies, riparian rights are either limited or do not exist. In these states, reasonable use of water by ripasian owners has been replaced by the right of prior appropriation. This right gives legal use of the water to a person who takes it first. Other persons may use any remaining water.

The term riparian comes from the Latin word ripa, which means riverbank.