[Thud]

The Oroville Dam won't fail completely. It can't unless it is nuked. The emergency spillway almost failed completely last week, and might do so next week if the warm storm arriving Sunday-Monday melts enough of the reservoir snowpack.

The best estimates I've found of reservoir dewatering in that instance range from top 30' of the reservoir (901' elevation above sea level down to 871') to the top 100' (901' elevation down to 801'). The latter might entail release of as much as 1.2 million acre feet of the reservoir's 3.5 million acre feet of storage.

A release of the top 30' would probably be in the 400,000 - 500,000 acre foot range. The next big reservoir downstream from Oroville has a capacity of a million acre feet so its dam might be able to handle that if that reservoir is sufficiently emptied by then. But the intervening cities would be gone.

[ridesthemiles]

INFO: There are 325,851 gallons of water in an acre foot.

Acre foot==
1 acre of land (43,560 sq ft) covered 1 foot deep in water.