What doctrine grants states control over all water resources within their borders?

The doctrine that grants states control over all water resources within their borders is known as the Doctrine of Prior Appropriation. This legal principle is based on the idea that state governments have the authority to allocate water resources, often prioritizing the use of water based on a "first in time, first in right" system. This means that those who have historically used a water source have senior rights to it compared to later users. In managing water resources, states can issue permits and regulate usage to ensure that water is allocated fairly and sustainably, particularly in areas where water may be scarce.

This doctrine is particularly relevant in arid regions where water availability is critical for agricultural, industrial, and municipal needs. By controlling water rights, states aim to prevent conflicts over water access and to promote responsible use of this essential resource. Understanding Prior Appropriation is crucial for anyone involved in land use and real estate in these regions, as it directly impacts property rights and development possibilities.