Planes seed the clouds every day. Tropical Storm Dennis dumped more than 20 inches of rain on the Everglades. But is south Florida satisfied?

No, because the region still faces the most severe drought in its history.

Lake Okeechobee, the 750-square-mile natural lake that nourishes 3 million people and a billion-dollar agricultural industry, dropped to an all-time low July 29 after a 14-month decline.

And the controversial cloud-seeding program, which started at the beginning of August, "hasn't proven successful yet," said Larry Nunn, spokesman for the South Florida Water Management District.

"We're facing a 1-in-700-year drought," said Nunn, citing statistical probabilities.

Although the lake, fourth-largest natural lake in the nation, has risen about a foot since its low point of 9.75 feet, it still remains about six feet below optimum levels for this time of year and seven feet less than its ideal depth if the region is to avoid extreme drought next spring.

Water management officials have predicted that consumption may be ordered cut back as much as 50 percent if conditions do not improve before the dry season arrives in November. Cutbacks of 10 percent for residences and 25 percent for farms imposed at the peak of the spring drought in May have not been lifted.

This is the time of the year when people in the subtropics look to the skies for daily ground-soaking thunderstorms to build up a reserve for the half year without rain.

Tropical Storm Dennis was a cruel storm. It flooded agricultural areas south of Miami so that farmers, citing crop losses of 25 to 100 percent, appealed for federal disaster aid for the rotting avocados, limes, okra, squash and sweet potatoes. It dragged a 300-mile-wide train of rain up the coast, but bypassed the lake, which supplies water to the region each dry season.

The deluge which pounded the coast could not be pumped back to the lake because of an inadequate canal system. So if the precious water could not be stored, it was lost to the sea.

"Dennis fell on the wrong place," said Dalton Yancey, vice president and general manager of the Florida Sugar Cane League. He said, however, the area around the lake has recovered from its parched appearance in May, when the drought affecting 42 states began drying up the swampy Everglades and created numerous sinkholes in central Florida.

With an especially wet August, rainfall in Miami is still 5 1/2 inches below normal for the year, based on a 30-year average.

Insufficient rainfall compounded by four decades of phenomenal growth along Florida's Gold Coast have stretched the area's finite water supply. The ground wells and canals which supply drinking water must remain sufficiently full to hold back the salt water that stands ready to intrude.

The water management district embarked on the cloud-seeding program with $450,000 in disaster relief granted by Gov. Bob Graham as a last-ditch effort to raise the lake even though meteorologists said they could guarantee no results.

All they can rely on are statistics which show a 10 percent increase in rainfall in experimental cloud-seeded areas over a long period.

"Most of the time you get some rain in 10 minutes, but the cloud might have rained anyway," said Andrew I. Watson, a National Oceanic and Atmospheric Administration meteorologist who flies a cloud-seeder daily. "It's definitely a gamble."