Decline in water flow at Silver Springs raises sharp disagreement
Published: Friday, June 1, 2012 at 6:49 p.m.
Last Modified: Friday, June 1, 2012 at 6:49 p.m.
OCALA — There has been no shortage of disagreements between supporters of the proposed 25,000-acre Adena Springs Ranch in Marion County and environmentalists who have serious concerns about it.
Now there is a growing disagreement about an abrupt decline in the flow of Silver Springs near the proposed ranch, and both sides agree the current drought can't account for it all.
At the center of the feud is whether the cattle operation planned near Fort McCoy should get a 13.2 million gallons-per-day water permit from Florida water regulators, and whether pumping that much water would harm an already diminishing Silver Springs.
Both sides agree that the 70-year average Silver Springs flow has nearly free-fallen from 790 cubic feet per second (or about 510 million gallons per day) before 2000 to 535 cfs. between 2001 and September 2011.
Both sides also agree that until 2000, the spring's flow was proportional to the rainfall that recharged it. After 2000, both sides agree, something happened and the flow decreased despite consistent rainfall.
"And it happened dramatically," said William Dunn, a Gainesville environmental scientist hired by the ranch to help in its water application.
Dunn said the spring's decline since 2000 has not been because of over-pumping, but possibly because of some "cataclysmic" event that has redirected water away from the spring.
Dunn said this theory, which is being reviewed by the St. Johns Water Management District, explains the spring's decline.
The water district, which will decide on Adena's application, did not return telephone calls for this story.
Robert Knight, an aquatic and wetland scientist who has studied Silver Springs for decades, said Dunn's theory is nonsense.
Meanwhile, Adena Springs Ranch owner billionaire Frank Stronach has hired environmental marketing consultant Sandra Anderson in Tampa to help get out the message that the spring won't be harmed by the ranch's water use.
"Unfortunately, most people are not aware of the facts regarding the project, or are commenting out of emotion or misinformation," she said on Friday.
A website explaining the ranch's side of the story is scheduled to be launched next week at Adenaspringsranch.com.
During a meeting this week, Dunn reiterated that the ranch likely won't need the full 13.2 mgd to irrigate grass to feed its cows. He said even if the full amount were withdrawn, the depth of the aquifer outside the ranch area would decrease only about 1.25 inches and about three-quarters of an inch in the Silver Spring area. In its water application, the ranch estimated it would have as many as 30,000 grass-fed cows on the property.
Dunn said the limerock that makes up the vast underground maze under the spring shed is always changing and susceptible to "time, chemistry and erosion," and that it could have changed, rerouting water elsewhere.
Knight said the theory of an underground event that's sending water away from the springs is unlikely.
"I think they're really clutching at straws," Knight said of Dunn and other Adena supporters. Knight contends the decline is due to over-withdrawal. He is director of the Howard T. Odum Florida Springs Institute at the University of Florida.
Knight said that, although the theory of a "cataclysmic" underground event is a convenient explanation to distract attention from over-pumping, "we don't have any evidence of that (theory) at all."
Knight said the simplest and most reasonable explanation is that due to over-withdrawal of water from the aquifer, there's a lack of water to replenish the spring. He also said that the lower volume of water in the aquifer could be naturally causing underground water to go toward springs with lower elevations.
Evidence of that happening is seen with Rainbow Springs compared to Silver Springs. Knight said Silver Springs has lost about 32 percent of its flow during the past decade, while Rainbow Springs, about 25 miles away, has lost only 15 percent. The difference between the two and their shared 2,000-square-mile watershed is that Rainbow Spring is about a dozen feet lower in elevation, Knight said.
In addition, Rainbow's flow has surpassed that of the Silver Springs, another sign that the aquifer level has shrunk enough to favor springs of lower elevations.
He said similar problems have occurred in North Florida.
"They're in la-la land to think their pumping is not going to have an effect," Knight said.
Of the theory of a cataclysmic event under Silver Springs that would move water elsewhere, Knight said the water would still have to be accounted for elsewhere.
"You would find it … and they haven't. That's why I don't think it's a plausible explanation," he said.
Knight said the explanation as to where the missing water is simple.
"It's showing up in everybody's well, peanut fields," he said. "We're just reproducing what Southwest Florida went through … and creating our own nightmare."