Prior appropriation: first in time, first in right

The rule in one sentence

Under prior appropriation, the person who first diverted water from a stream and put it to a beneficial use has the better right to that water, ahead of everyone who came later. Water people call it “first in time, first in right.” It is the opposite of the eastern riparian system, where owning land along a river gives you a share of it.

The rule is written into Colorado's Constitution, adopted at statehood in 1876. Article XVI, Section 5 declares the water of every natural stream to be the property of the public, dedicated to the use of the people. Section 6 says the right to divert unappropriated water to beneficial uses shall never be denied, and that priority of appropriation gives the better right between users.

Where it came from

Miners and farmers in the 1850s and 1860s took water from streams and carried it, sometimes long distances, to claims and fields that were nowhere near the bank. Riparian law could not work in a dry country where the best farmland was often away from the river. In Coffin v. Left Hand Ditch Co. (1882), the Colorado Supreme Court upheld a ditch that carried water from the St. Vrain watershed to land along Left Hand Creek, holding that the first appropriator has the superior right whether or not the land touches the stream. The case is still taught as the foundation of the “Colorado Doctrine.”

What a water right is — and is not

• A right to use, not to own. The water belongs to the public. A water right lets its owner divert and use a decreed amount, from a decreed source, at a decreed place, for a decreed purpose.
• Beneficial use is the measure. Irrigation, municipal supply, industry, stock watering, augmentation and instream flows held by the state are examples. Water taken and wasted is not a beneficial use.
• A decree sets it down. Since the Water Right Determination and Administration Act of 1969, Colorado's seven water courts confirm (“adjudicate”) water rights and changes to them.
• Rights are property. They can be bought, sold or changed to a new use or place — through water court, and only if other rights are not injured.

Senior and junior

A senior right is an older one; a junior right is newer. On a stream with plenty of water, everyone diverts and the order does not matter. When the stream cannot meet every decree, the order is everything: the State Engineer's staff — Division Engineers and water commissioners in each of the seven water divisions — require junior rights to stop diverting so that water reaches the senior right downstream. That demand is called a call.

The date that matters is usually the appropriation date, when the water was first put to use or the first steps were taken. Because Colorado adjudicated rights in rounds, DWR ranks rights with an administration number that combines the appropriation date with the date of the previous adjudication. The smaller the number, the more senior the right. A right decreed late for an early use can therefore rank behind rights adjudicated before it.

What it means in a dry year

Prior appropriation does not share shortages evenly. In a short year the most senior rights may receive their full decreed amount while the most junior receive nothing at all. That is why the priority date of a ditch, a city's supply or a well's augmentation plan can matter more than its size. Junior users protect themselves with storage, by leasing or buying senior water, or with augmentation plans that replace their depletions.

Two refinements soften the rule in practice. A futile call: a junior is not curtailed if shutting it off would not actually deliver usable water to the calling senior in time. And exchanges and augmentation let a junior divert out of priority by replacing the water it takes, under a decree or an approved plan.

Use it or lose it

A water right that is not used can be lost. Water rights can be found abandoned when the owner intended to give up the use, and a long period of non-use can be evidence of that intent. Changes of water rights are also limited to the amount historically consumed, so an unused paper right is worth less than one that has been used.

Seeing priority in BasinMind

BasinMind reads the active calls DWR posts to CDSS and shows them on Today and the Map, with each calling structure's priority date. The Structures page shows a ditch's decreed rights. These are readings of public records — the water commissioner for your district makes the actual administration decisions, and only a water court decree defines a right.