After 15 years of booming development and tropical deluges, federal emergency managers have redrawn Miami-Dade County's badly outdated flood-risk maps. Broward is in the midst of a similar update, with preliminary maps due out for public review in June.

The changes are literally across the map, mostly in small pockets but large swaths, too. Much of Sweetwater, for instance, went from unclassified by the Federal Emergency Management Agency to high-risk flood zone -- a tag that comes with a price.

``We fought tooth and nail against it,'' said Mayor Manuel Maroño. ``I find it extremely ironic since we spent over $20 million on improvements. It's one of those Catch 22s.''

The city bought huge pumps and other upgrades to fix notorious drainage woes. State and federal agencies, FEMA among them, spent $50 million on two massive storm water basins. Yet lower risk added up to higher premiums, Maroño said -- about $1,400 a year for flood policies many residents will now require.

``I've got a lot of phone calls and a lot of complaints,'' he said. ``I'm extremely unhappy about being put on the map.''

On the flip side, a third of unincorporated Miami-Dade was dropped from high-risk to lower-risk zones. That could potentially save homeowners money in reduced premiums -- but they may need to look up the changes themselves to find out.

The map updates are part of a $1 billion-plus nationwide effort by FEMA to improve and modernize obsolete, often inaccurate topography maps used to set federal flood insurance rates and local building code elevations. FEMA spokesman Clark Stevens said pinpointing flood hazards more precisely helps protect residents and property from catastrophe.

``This process ensures that communities have the best possible information when making decisions on how to mitigate and insure against the risks posed by floods,'' he said.

But thousands of homeowners in South Florida and the state -- who already hold three times more National Flood Insurance Program policies and pay three times more in premiums, nearly $1 billion, than the next closest state -- will feel the difference where it hurts: the wallet.

For starters, last month FEMA raised annual flood premiums nationwide, by 8 percent on average, 10 percent for highest-risk coastal real estate. Map changes may help offset the hike for some homeowners, but shifting zones and higher elevations will hit others with hundreds, even thousands of dollars more in insurance costs.

Miami-Dade's flood map changes became official in September, but many residents first learned about them in recent weeks in letters from banks, mortgage lenders and insurance agents demanding federal flood insurance. It's required for federally backed mortgages in flood zones, and many private lenders insist on it as well.

LACK OF AWARENESS

Despite a string of public meetings, mailings, advertisements and outreach efforts by FEMA, cities, Miami-Dade's Department of Environmental Resource Management and the South Florida Water Management District during the two years it took to develop the maps, flood mapping remains poorly understood by most of the public.

The vast majority of Miami-Dade and Broward -- low-lying, heavily populated counties bordered by the Everglades and the Atlantic Ocean in a hurricane hot zone -- were and remain in flood-risk zones. But the remapping brought new technology, and precision, to FEMA's measuring stick of risk: a hypothetical one-in-100-year flood.