Water Law

This concept of water as property that could be used away from the land on which it was found was in marked contrast to areas where water was plentiful. For example, east of the Mississippi water was deemed to run with the land and was available to be used if it was found on the premises. No special permission was needed to use water. In fact, a riparian owner could use as much water as needed so long as this use would not impair the use by other landowners.

Colorado’s response to scarce and inconvenient water resources was to create the prior appropriation doctrine. The following are basic tenants of this legal system peculiar to the water-scarce western United States.

• Prior Appropriation – The water law doctrine that confers priority to use water from natural streams based upon when water rights were acquired. Holders of senior rights have the first claim to withdraw water over holders who have filed later claims or own what are called "junior water rights". In times of shortage water is provided in full to the most senior rights with junior rights being cut off. The Colorado State Engineer administers water in the state. Ownership of land is insufficient to convey a right to use water.
  
• Water Right – A property right to make beneficial use of a particular amount of water with a specified priority date.
  
• Beneficial Use – As defined by the Colorado Revised Statutes, 37-92-103 "a beneficial use is the use of that amount of water that is reasonable and appropriate under reasonably efficient practices to accomplish without waste the purpose for which an appropriation is lawfully made . . ." A beneficial use is considered to include domestic, agricultural, industrial, and recreation [including fishery or wildlife].
  
• Call – a demand that upstream water rights with junior priority dates cease diverting, so that water may be delivered to a downstream senior water right holder.
  
• Reservoir – A body of water used to collect and store water.
  
• Return Flows – Water that returns to a stream after it has been used.

People who turn on their faucets in the Denver Water service area don't know whether the source of their water is the South Platte River located on the east slope of the mountains or from the Colorado River or its tributaries on the west slope. The Colorado Constitution recognizes no differences either, and states the "Water of every natural stream.....is hereby declared to be the property of the public....." The reason the Constitution and the courts recognize no geographic advantage in water is because water rights are a right to use water. So long as water is put to a recognized beneficial use and water is available, anyone may go to water court and get a decreed right to use water.

 Approximately 70% of Colorado's population is located on the Front Range and approximately 70% of the water in the state is located on the West Slope. This difference has resulted in water being moved out of the West Slope Colorado River basins to the Front Range for beneficial uses such as for human consumption, industry and agriculture. The very earliest transbasin diversions were for agricultural purposes, but water for municipalities followed soon thereafter. In addition to Denver Water and all the cities it serves, many other cities and towns are dependent on the use of water brought from the West Slope to the Front Range to supplement native supplies. These cities include Englewood, Boulder, Fort Collins, Colorado Springs, Pueblo, Aurora and many others. Denver's water in the Blue River, tributary to the Colorado River, is stored in Dillon Reservoir and moved through Roberts Tunnel to mingle with waters of the South Platte on which Denver also holds water rights.

 When water is moved from one basin to another, courts may apply restrictive conditions. For example, the Blue River Decree indicates Denver may not use water for uses outside areas socially and economically integrated into the city, and is limited to municipal uses.