How CVP allocations work (and when they're announced)

A CVP allocation is the share of contracted water the Central Valley Project will deliver this year, set as a percent of contract volume. The US Bureau of Reclamation runs the CVP and announces the number, usually starting in late February, then revises it upward or downward through spring as hydrology becomes clearer. A 40 percent allocation does not mean a farm gets 40 percent of what it wants. It means 40 percent of the specific volume written into its contract.

Contract class is everything

The single most important thing to understand about CVP water is that not all contractors are equal. The allocation you hear quoted depends entirely on which class is being discussed.

• Settlement and exchange contractors hold the most senior water rights on the system. In most years they are announced at 75 to 100 percent, and they are the last to be cut.
• Agricultural service contractors north of the Delta and south of the Delta are the volatile middle. South-of-Delta ag is the number the whole state watches, because it swings hardest between wet and dry years.
• Municipal and industrial contractors and wildlife refuges have their own schedules and floors.
• Friant Division water on the east side splits into Class 1, the firmer supply, and Class 2, the junior wet-year water that shows up only when there is extra.

The announcement calendar

The initial allocation typically lands in late February. Reclamation deliberately starts conservative, because it is forecasting the rest of the winter and spring runoff it has not seen yet. As storms bank snow and reservoirs fill, the number is revised, often several times, into May and June. A rising series of announcements through spring is the normal shape of a decent year.

Worked example: reading the south-of-Delta ag line

South-of-Delta agricultural service is the class to watch, so track it directly.

The south-of-Delta agricultural line on the chart and its row in the table above carry this class's actual announcements as Reclamation posts them. Read them as a sequence: the first figure of the year is the cautious opener, and each later figure is the revision as the water year firmed up. When people say the CVP had a good year or a bad year, this is usually the line they are pointing at.

The Waterline reports these announcements as published by Reclamation. It does not forecast where an allocation will land.