LEE COUNTY, Fla. - Why is the floodwater still around more than a week after the downpours from Tropical Storm Fay? The answer? Sheet flow. But what is it?

"You have this water moving trying to find its way to the Gulf of Mexico, it can't sink into the ground because its already saturated, so its just kind of meandering along, trying to find its way," said Susan Sanders, spokesperson for the local office of the South Florida Water Management District.

Because Florida is so flat, when water is draining off, it looks for the creeks and rivers, but otherwise on flat surfaces, it just flows down, like a sheet.

"It finds its way down (from inland), and as it gets down here it begins to run into things that block it like I-75, like increased development," Sanders said.

Those blockages to the natural drainage paths, things like buildings and highways, lead to the flooding we're experiencing now.

"And so what happens is, all of this is compressed, all of the water is moving here," Sanders said.

The problem can be described like a funnel; there's already a tremendous amount of water trying to drain through a narrow opening. After all the development over the past several decades, that hole has gotten much smaller. Now the same amount of water is trying to move through a smaller opening, causing it to back up and take longer to drain.

A study after the 1995 floods in Bonita Springs called for changes to drainage, like clearing low areas, and essentially opening more holes for water to flow.

"And some of those things have already been done, and been implemented," Sanders said. "In actuality, if those things hadn't been done, we might be seeing a much more severe situation than we're seeing today."