A controversial plan to pump water out of a Tampa sinkhole to supplement the flow of the Hillsborough River won unanimous support Tuesday from the Southwest Florida Water Management District board.
The city's $11 million plan calls for pumping up to 2 million gallons a day from Blue Sink, a complex of sinkholes in Sulphur Springs, then piping that water to the base of the dam on the river and pouring it out.
The water from Blue Sink is supposed to help replace the river flow that was lost when the city built the dam in 1897 to create a reservoir that provides Tampa's drinking water. The restored freshwater flow will help hold the salinity of Tampa Bay in check, which is important for the health of the snook and other fish living there.
However, people who live around Blue Sink fear pumping water from the sinkholes will create even more sinkholes, not to mention draining their lakes and sucking their private wells dry.
"We're just concerned about what might happen," Jim Wilson of the North Forest Hills Neighborhood Association told the board of the agency commonly called Swiftmud.
Tampa Water Department chief Brad Baird said that the neighbors have nothing to worry about. He pointed out that the permit requires regular monitoring of Blue Sink, as well as a promise by the city to fix any problems that the pumping might cause.
The city's engineers, in their application for a 30-year pumping permit, estimated that at most the city would need to pump water from the sink just 287 to 318 days out of a year. Some years, Baird said, they might not need any water from the sink at all.
The city's studies say none of the 800 wells within a 1-mile radius "is expected to be significantly impacted" by that amount of pumping. At most they might drop two-tenths of a foot, the city's engineers predict.
But those conclusions are based on a pair of 30-day pumping tests and a computer model, and the neighbors are not buying the test results.
Hydrologists have repeatedly pointed out that the computer model commonly used for Florida water permitting assumes that what is underground is sand. It's actually karst, a Swiss cheese arrangement of crumbling limestone, which alters both the speed and the direction of the flow of the aquifer.
Not all the neighbors felt the same way. Barbara Ewanowski, whose family has long owned Ewanowski Spring, pointed out that her spring provides the water that flows through Blue Sink. But since the sinkhole was plugged with trash and other debris, the water has repeatedly backed up and flooded her property, killing dozens of oak trees.
Pumping water out of Blue Sink would help restore her property, she said, so she's supporting the project.
So is Friends of the River, the group that has pushed hardest for restoring the Hillsborough's historic flow into Tampa Bay.
"I am confident the use of Blue Sink will not endanger the environment," John Ovink of the Friends of the River told the Swiftmud board.
Swiftmud is more than just the regulator issuing the permit for the Blue Sink pumping.
It's also Tampa's partner on the Blue Sink project, paying half of the tab. Swiftmud also happens to be the regulator that pushed for restoring the river's flow into Tampa Bay and is now overseeing how Tampa carries out that order.
Now that Swiftmud has approved the permit, construction is likely to begin next year and finish in 2015.