Unlike the Riparian doctrine, the Prior Appropriations doctrine applies to interstate and international water sharing.

The Prior Appropriations Doctrine is a Necessity to Interstate and International Water Sharing

The Prior Appropriations doctrine, also known as the “first in time, first in right” doctrine, is a legal principle that governs the use of surface water in the United States. The doctrine applies to both interstate and global water sharing. It has proven indispensable in the management of water resources. Prior Appropriations dictates that water rights will be granted according to when the first user uses water. This means that users who use and take water earlier have a higher priority in receiving it (Wyoming Water Law 2020). The law codifies this priority, which is crucial for managing surface water resources. It ensures users are able to get the water they require, while also protecting sustainability. Prior Appropriations is the main legal principle in water law for the west United States (Doremus 2020). The reason is that water resource management in the western United States requires careful consideration due to its harsh climate. The Prior Appropriations doctrine was adopted by multiple west states including Wyoming, Colorado and New Mexico (Wyoming Water Law 2020).