A pending adjudication of water rights in Colorado offers an encouraging new twist on an old problem. It appears that an assertion of an implied federal reservation of large-scale water rights for Naval Oil Shale Reserve development may preempt the rights of present water users in a manner that will actually benefit water district members and protect the environment of a water-scarce region.

In the Western United States, water is generally governed by the law of appropriations. That law holds that a water user acquires rights in water by the physical diversion and beneficial use of water. The user need not own land adjacent to the water-course; he has the right to transport the water many miles over the lands of others to reach his point of use. The law is a first-in-time, first-in-right system. A diverter may consume as much water as he reasonably needs, so long as he does not interfere with the use of the "senior" users who appropriated before his diversion.