Amid punishing drought, federal water managers are projecting — by a very narrow margin — that Lake Mead won't have enough water to make full deliveries to Nevada and Arizona in 2018.

A 24-month projection released Tuesday comes with the largest Colorado River reservoir 36 percent full.

But it's still expected to clear the trigger point this year to avoid a shortage declaration in 2017.

For 2018, the federal Bureau of Reclamation projects missing the mark by under a foot.

Officials note that reservoirs in Colorado, Wyoming, Utah and New Mexico are at higher levels this year than in recent years.

That has them hoping to still avoid declaring a shortage that would cut Arizona's water allocation by 11.4 percent, and Nevada's by 4.3 percent.

Combined, that's enough water to serve more than 600,000 homes a year.