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Rain helps, but leaves a long way to go to alleviate drought

Bobby Cotton of Tampa’s Stormwater Department lifts a drain cover while trying to remove excess water from the 4600 block of W San Miguel Street in South Tampa on Monday. He said he expected to service several locations due to the rain.

MARTHA RIAL | Times

Bobby Cotton of Tampa’s Stormwater Department lifts a drain cover while trying to remove excess water from the 4600 block of W San Miguel Street in South Tampa on Monday. He said he expected to service several locations due to the rain.

After several days of drenching rains, and now forecasts calling for thunderstorms through the week, can we finally turn our attention away from all this drought talk? Not really. The recent rains have helped a lot, but we're still a long way from even average.

How much rain do we need?

Tampa Bay has a 30-inch rainfall deficit for the last 36 months, according to the Southwest Florida Water Management District. As of Monday morning, the city of Tampa was 1.91 below its yearly average, while St. Petersburg was down 5.94 inches, the National Weather Service said.

Any chance water restrictions will be eased?

That topic is not on the agenda of Swiftmud's monthly meeting.

Have the rains helped?

Water usage drops about 30 million gallons on rainy days, according to Tampa Bay Water, the regional water utility. This week's showers also will be beneficial because they are scattered and at a light enough intensity to improve saturation, said Granville Kinsman, Swiftmud hydrologic data manager. Generally, more than 70 percent of rain that falls here dissipates into the atmosphere. About 13 percent goes to runoff and only about 13 percent makes it to the aquifer.

Is this the beginning of the rainy season?

No. The "Bermuda High" has yet to set up over the Atlantic Ocean, pushing sea breezes westerly across the Florida peninsula, where they heat up, then collide with cooler water from the Gulf of Mexico, producing thunderstorms.

What about the Floridan Aquifer? Does this help?

Yes. Measurements at wells around Central Florida show heavy spring rains stabilized underground water levels that usually plunge in the dry season. Levels have risen nominally, Kinsman said. But there is a long way to go. Groundwater levels in Pasco, Pinellas, Hillsborough and Polk counties were on average 7.76 feet lower this April than at the same time in 2005.

Are reservoirs showing improvement?

Hillsborough Reservoir in Temple Terrace is up 2 feet, to almost 21 feet. But regional water managers drained the 15-billion-gallon C.W. Bill Young Regional Reservoir in Fort Lonesome to 130 million gallons, then halted usage in mid March. That amount of water would last area customers about one day.

What about the Hillsborough River, the drinking water source for the city of Tampa?

The river has improved this spring but remains at a historic low, a "1" on a "1-to-100" scale, based on data from the U.S. Geological Survey. The problem has been lack of rain in the Green Swamp, headwaters for the Hills­borough and several other rivers. Regional water managers say four to five weeks of summer rain typically are needed to raise the river to levels that they can tap into it.

Why is the Green Swamp so important?

The 560,000-acre wetland/uplands not only feeds the headwaters of the Hillsborough, Ocklawaha, Peace and Withlacoochee rivers, but also recharges the 100,000-square-mile Floridan Aquifer. The swamp is 15.45 inches below the historical norm, Kinsman said.

An early start to hurricane season?

The National Hurricane Center is monitoring a disturbance over eastern Cuba that has a slim chance of developing into a tropical cyclone. A hurricane hunter aircraft will investigate the system today, if necessary. Hurricane season officially starts June 1.

Rain helps, but leaves a long way to go to alleviate drought 05/18/09 [Last modified: Saturday, May 23, 2009 12:42pm]

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