News: Worsening drought feared as South Florida water levels drop
Posted on December 20, 2010Palm Beach Post
By Eliot Kleinberg
12/20/10
Good thing those cold spells are over. Now all South Florida has to worry about is a drought.
The May-through-October wet season accounts for two-thirds to three-fourths of the year's rainfall. The dry season accounts for the rest.
If you have a drier-than-normal wet season, you've got big trouble. But if you have a drier-than-normal dry season, it's not the end of the world.
"You expect less rainfall in the dry season," South Florida Water Management District official Susan Sylvester said last week .
But, she said, "What you don't expect is long periods of no rainfall."
South Florida's water bind is a cause for concern right now but could become a far more serious issue in coming months.
Already the tinder-dry region is under a growing threat of wildfires; several brush fires have erupted along the Treasure Coast.
Water levels are plummeting. Lake Okeechobee is about 2.25 feet below normal; a bigger drop could threaten its role as a key water supply for Glades farmers and a backup supply for the coast. The same goes for water conservation areas.
If water levels drop enough, fish and wildlife could be stressed.
The region already is under year-round lawn-watering limits.
A water crisis is about supply and demand. Rainfall deficits considered moderate or even minor at the end of World War II, when Florida had 3 million people, now generate a crisis, when six times as many people are turning on the tap.
No one's talking about going to tougher restrictions. But the district is urging people to take the current situation seriously and make sure they're using water efficiently.
Rainfall totals as measured at Palm Beach International Airport are grim. Although a steady drizzle fell all day Saturday, the impact was minimal: PBIA recorded less than a third of an inch. Since the dry season began, rainfall is down 4 inches; since the wet season began in early June, it's down more than a foot.
Low rainfall totals over the past year and a half have added to the deficit.
The 2008-09 dry season, the third-driest on record across the water management district, was followed by a below-average wet season. The 2009-10 dry season had above-average rainfall but was followed by a below-average wet season this summer.
In a typical rainy season, about half of rainfall comes from a tropical system - anything from a monster hurricane to a tropical wave. When that doesn't happen, "it hurts," National Weather Service meteorologist Barry Baxter said. And this year, except for a few soggy waves, it didn't happen.
So conditions already were dry when the dry season started in early October, two weeks early.
Forecasters said the strongest La Niña since 1955 was expected to bring "exceptionally dry conditions." The past few months have seen record rainfall deficits in some areas.
For the calendar year, rainfall across the district is only 10 percent below normal along coastal Palm Beach County and the Treasure Coast, and at or near normal in interior areas, where much of the region's water is stored.
But Sylvester says that's misleading.
She said the region experienced an abnormally wet 2009-10 dry season, and a lot of that water had to be dumped to meet regulation schedules set by the federal government.
Then this year's wet season was below normal, and those storage areas did not fill all the way. They've been dropping precipitously as the dry dry season progressed, Sylvester said.
Wildlife biologists are monitoring the impact on wildlife.
In the short run, lower rainfall might help species such as wood storks, because the fish on which they feed are more concentrated, Florida Fish and Wildlife Conservation Commission spokeswoman Gabriella Ferraro said. But, she said, "If there's too much lack of rainfall, there will be no fish."
She said wading birds in the Everglades build colonies on tree islands surrounded by water. If levels drop enough, predators can get to nests, and birds might abandon them and move elsewhere.
The short-term forecast isn't promising. It calls for continued below-normal rainfall across the region for the next week or two.
Will a really wet rainy season save the day? "It's too far in advance to say," Baxter said.
For now, long-range models show that La Niña will remain weak to moderate; the stronger the phenomenon, the less rainfall.
But with the wet season still a half-year away, Baxter said, "We're just throwing darts at the board."
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Drought index
The Keetch-Byram Drought Index, which measures soil dryness on a scale of 1 to 800, shows most of South Florida in the 'moderate' (491-630) range.
Palm Beach 573
Martin 570
St. Lucie 592
Okeechobee 538
Glades 574
Hendry 569
Indian River 529
Broward 527
Miami-Dade 464
Monroe 399
Readings as of Sunday. Source: Florida Division of Forestry.
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