Anatomy of a drought

The five stages, and where to watch each one

1. Snow. Nearly all of it is decided by April. A thin snowpack — or a warm one that leaves early — is the first, cheapest warning. Watch: the statewide snowpack page and each district’s Snow & runoff tab.

2. Rivers. The melt that never comes shows up as a June peak that never arrives. The honest measure is the flow’s percentile for the date, not “below average”. Watch: the Drought tab’s barcode, where every dry year in a century is a warm band.

3. Reservoirs. Storage is the shock absorber: it keeps taps and ditches running through the first dry summer, and pays for it by starting the next year low. Watch: each basin’s Reservoirs tab.

4. The calls. When the river cannot serve every decree, administration answers — calls reach further back in time, and more rights go junior to the calling right. Calls LAG the river: they linger while reservoirs refill and owed water is repaid. Watch: the Drought tab’s “law’s own drought gauge”, and anatomy of a call for the machinery.

5. Groundwater. The valley aquifers feel a drought last — pumping rises exactly when recharge falls — and recover slowest, sometimes by years, sometimes not at all. Watch: each basin’s Groundwater tab, and pumping now, depletion later for why the lag exists.

What this does not let you conclude

The chain is typical, not guaranteed — a monsoon can rescue a bad snow year, and a dry fall can squander a good one. A deepening call is not a pure drought gauge: demand grows too, and administration responds to both. And no stage of this chain forecasts the next year — the site’s own forecast report card shows how seasonal predictions behave in exactly the years this lesson is about. The chain tells you where to look and in what order; it does not tell you what you will find.