A brief recap of how the tussle in Congress over FEMA funding went down: A little while back, it looked like FEMA was going to run out of money in its disaster-relief fund before Sept. 30, the end of the fiscal year. House Republicans offered up $1 billion in FEMA funding to help cover the gap between now and then, but insisted that money would have to be offset by cuts elsewhere. Democrats balked. And, since this was all wrapped up in a bill to fund the federal government, it looked like there was going to be a big government shutdown. Except suddenly FEMA announced that it didn’t need the money after all.

(Monika Graff/Getty)

The answer, basically, is that FEMA has stopped working on some projects, and is betting against another natural disaster or any other unexpected costs, anytime soon.

As it turns out, FEMA has been conserving funds for some time, ever since it looked like Hurricane Irene would hit the mainland in August. About $450 million in funds for longer-term reconstruction projects has been put on hold. That’s left a cushion of funds for emergency and protective measures — things like paying firefighters or conducting search-and-rescue missions. Everything else is in limbo until Friday.

Disaster-management experts say this is unprecedented. “The disaster-relief fund has never been this close to zero balance,” says Mark Merritt, president of Witt Associates. And while the uncertainty has practical impacts — thinks like putting a hold on road construction in flood-devastated Vermont — Merritt notes that the longer-term implications are even more alarming.

Here’s what he means. Congress and the White House have agreed to $2.7 billion to fund FEMA between this Friday and mid-November. But that money could be eaten up very quickly, especially as FEMA resumes projects that are currently on hold (since now it won’t get that extra $1 billion). What’s more, the agency is still conducting assessments of the damage caused by Hurricane Irene in states like Vermont, Connecticut and New York, and that bill could turn out to be quite costly. Which means that $2.7 billion could get stretched thin between now and November.

On top of that, whether the funds last depends on whether we have another billion-dollar disaster, say a major hurricane or tornado, before mid-November. That’s a risky bet. Remember, it’s still the height of hurricane season. And Joe Romm of Climate Progress points out that FEMA emergencies have been steadily rising over time, with 2011 setting new records:

“Congress is gambling that nothing more will happen between now and mid-November,” says Merritt. And if they’re wrong? We get to go through this fight all over again.