Lehrer said in his comments said that, on balance, the reforms "are incredibly modest."

Lehrer said that more than half of the properties most at risk won't see rate increases even if all of the reforms go into force. He said, "The private sector's role in flood insurance for homeowners will grow only slightly," adding that anyone "looking to privatize flood coverage in a serious way will have to make further reforms" when authorization of the National Flood Insurance Program runs out in in 2017.

Still, Lehrer said, each year that subsidies for development in flood-prone areas continue, more people will move into harm's way. "As the backlash to the reforms demonstrates, once they are there, it is beyond difficult to get them out," Lehrer said.

He said that "this has very real human costs" because undoing even a modest phase-out of flood-insurance subsidies "almost surely would mean plucking more people off of roofs with helicopters during the next massive flood or seeing more of them perish."

And, Lehrer said "things appear certain to get worse. Ocean levels have been rising for at least 10,000 years, and climate change may accelerate this process in the future."

Moreover, Lehrer said the real problem isn't the flood-insurance program itself because the NFIP's $25 billion in unpayable debt "isn't a fiscal calamity in the context of a $3.5 trillion a year budget.

"But Congress' seeming inability to stick with modest reforms—even when they produce far more winners than losers—proves how hard it is for the federal government to do anything that improves the nation's finances," Lehrer said. "If members of Congress can't save flood-insurance reform, it's hard to believe they'll ever be able to fix far larger fiscal ills," he said.

At the moment, the Senate is considering whether to add S. 1610, the Homeowner Flood Insurance Affordability Act, as an amendment to S. 1867, the National Defense Reauthorization Act. The Senate will begin taking that bill up Monday, and the Senate leadership is considering whether to add S. 1610 as one of perhaps 30 proposed amendments to the bill. It is must-do legislation with strong bipartisan support.

That is not to say that Lehrer doesn't think that the bill could be modestly changed.

"A handful of people of modest means who are unexpectedly remapped into much higher risk areas may be socked with larger bills they can't afford to pay and should probably get some temporary relief as long as they occupy their homes," Lehrer said.

More seriously, he said, a longstanding rate-setting practice of ignoring levees that don't provide protection against 100-year floods has resulted in some people behind "decertified" or "uncertified" levees being charged much higher rates than they should be. Lehrer noted that developers and others blocked an effort to fix this, because it would have also required more of those behind the levees to purchase coverage.

"Other broader changes—even rate freezes for people of modest means who own their own homes—probably should be part of a negotiation," he said.