The Verification Venue · pointed at the queue hiding inside western water law

First in Time, Dried Up in Order

The popular picture of water in the dry West is a scramble. The law is closer to a waiting room with numbered tickets. When the river falls short, prior appropriation curtails the most junior right first, and entirely, before touching the next one, so a drought delivering forty percent of the paper leaves the oldest ditch whole and the newest user bone dry. Drag the river down below and watch the cutoff move. Then price the trades the rule makes possible, and the habit its forfeiture clause rewards.

Below is a typed river: six rights dated 1868 to 1987, decrees totalling 100.000 acre-feet, and no connection to any real stream. Every number on this page is recomputed in front of you from that register. Pick how the shortage is shared, drag the available flow, and watch who keeps their water.

Sharing rule for the same shortage

Both buttons allocate the identical flow. Neither is being recommended; the point is what each one does to the same drought.

The table is the accessible copy of the canvas: green means the decree is met in full, gold means partly cut, orange means dry. Orange hatching on the canvas appears only when the forfeiture rule further down is switched on.

Prior appropriation runs on a sentence older than most of the states that use it: first in time, first in right. The administrator sorts the rights by date and walks down the list, handing each right min(decree, what is left) until the river is gone. The allocation is therefore a deterministic function of exactly two things: the dated register and the available flow. Proportional sharing walks the same list with a different formula, share = flow × decree ÷ Σ decree, and spreads the same shortage across everyone at once.

At forty percent of aggregate decree, the seniority walk hands Willow Bend its full 30.000 AF, Highline a partial 10.000, and zeroes everything from 1889 onward. Switch to proportional and the same 40.000 AF becomes forty percent for everybody. Neither rule is fair in the abstract: seniority buys certainty for whoever got there first, proportionality buys shared pain. Notice what the value readout says too: with these typed numbers, spreading the water happens to deliver more crop value than the seniority walk, because the two highest-valued users sit late in the queue. That is an accident of this register, not a theorem, and it is exactly the opening a market tries to exploit.

A dry-year market, and the rule that poisons it

If a junior values water more than a senior, a voluntary lease makes both better off: the senior sells water worth little to them, the junior buys it dear. The page computes the gain exactly, (buyer value − seller value) × quantity, with quantity capped by the seller's delivery and the buyer's decree, and buyers already holding their full decree excluded. One honesty rule governs the best-lease line further down: when several different leases achieve the same top gain, it prints every one of them, most water moved first, and calls none of them the best. At the default settings the line reads as a tie: selling Willow Bend's water to Highline and selling it to Cedar Gulch clear exactly the same joint gain, moving different quantities to do it. Then switch on the forfeiture rule many western codes carry: use the water or lose the right. A holder who might sell must instead keep diverting up to the threshold, pouring on water they do not need, to keep the paper alive. Watch the leaseable quantity, and the gain, drain away as the threshold rises.

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Three limits, stated where you can see them. First, this page models the doctrine, not any state's administration: real systems add groundwater conjunctive use, instream flow protections, storage accounts and exchange rules, and no two states administer them alike. Nothing here describes a particular river or a particular water court's call. Second, the behavioural claim about forfeiture is a property of the model, not a finding about irrigators; whether real use-it-or-lose-it rules cause measurable waste is contested in the literature, and this page shows only what a holder does under the rule as written, which is checkable arithmetic. Third, nothing here ranks prior appropriation above or below riparian or correlative regimes: the proportional toggle is a deliberate simplification standing in for sharing ideas generally, not riparian law, which attaches to land beside the stream and behaves differently in ways this page does not model.