Special Reports

Experts: Spill won’t affect water supply

MANATEE — Officials and scientists say the Gulf oil spill would pose little danger to Manatee County’s water supply if it reaches local shores.

“It’s going to be primarily along the shoreline and coastline if it gets here,” said Joe Buerhot, a hydrogeological consultant with Enviro-Audit & Compliance Inc. in Palmetto. “As far as our aquifer and drinking water, absolutely no chance.”

Why? Several reasons, experts say, including where the county gets its water, the molecular differences between oil and water and the laws of nature and physics.

First, the oil would have to get here. That means it would have to travel some 340 miles, based on the spill’s reported position at noon Monday, to touch Manatee’s coastline.

Then it would have to find its way into Manatee’s water supply, whose sources are far from the coast.

“We get our water 40 miles inland and 1,200 feet deep,” Manatee County Public Safety Capt. Larry Leinhauser said, referring to Lake Manatee and two nearby artesian wells. “It’s not a possibility. Where we get our water from, it’s too far from shore.”

To reach the lake or wells, the oil would have to either go underground or travel through Tampa Bay and up the Manatee River. Neither path would be easy.

For one thing, the river’s current flows toward Tampa Bay. Experts estimate it would take days, maybe weeks, of sustained onshore winds of tropical storm or greater velocity to push any oil that far upstream.

“It would have to come up through the estuary system, and doing that is very difficult. It’s possible but improbable,” said Leo Swayze, principal of Hydrologic Associates USA Inc., an environmental consulting firm in Miami.

And if any oil did make it to the lake’s doorstep, there’s another barrier: The Lake Manatee dam.

“We could just open the floodgates and wash it right back out,” Leinhauser said.

Experts said the underground scenario is even less likely, primarily because oil and water don’t mix.

Because it is less dense than water and does not dissolve in water, crude oil initially floats on top when mixed with water. While oil eventually can clump into “tar balls” that sink when they become heavy enough, those clumps are too big to go beneath the Gulf floor and possibly make their way into the Floridan Aquifer.

That aquifer is a huge underground reservoir comprised of layers of porous limestone that provides 90 percent of Florida’s water.

It is protected by vary- ing layers of sand, clay and rock that would filter out any oil before it could reach the aquifer, experts say.

Also, water moves through the aquifer from the center of the state toward the Atlantic and Gulf coasts.

“It’s extremely unlikely that any contamination of any kind out in the Gulf would affect our drinking water supply,” said Cliff Harrison, a hydrogeologist and owner of EnHydro LLC, based in Palm Harbor.

The Southwest Florida Water Management District, which regulates and monitors water supplies in Manatee and all or parts of 15 other counties, referred all oil spill-related questions to the Florida Department of Environmental Protection.

“At this time, there are no potential threats to the aquifer due to the Deepwater Horizon oil spill,” DEP spokeswoman Amy Graham said in an e-mail Monday.

Duane Marsteller, transportation/growth and development reporter, can be reached at 745-7080, ext. 2630.