Here's a quickish way to understand what's going on in the Everglades. In the beginning, before there were sugar growers or suburban McMansions or Army Corps of Engineers in South Florida, there was a lot of water, and it moved very slowly, creeping clockwise from Lake Okeechobee down to Florida Bay. Graph No. 1 shows the pattern.
But now check out the satellite photo. That's South Florida today. The east coast of the state, of course, is now covered with urban development. The land below the lake has been converted into sugar plantations and other farms that drain fresh water out of the system and spew dirty water back into the system. And a bunch of levees and canals now slice through the heart of the Everglades, blocking the natural flow.
See those little dots scattered around the center of the map? Those are tree islands, and when the system was natural they were molded into the same patterns as the arrows in the graph. But now they are scattered and irregular.
Graph No. 2 shows that there's a lot less water in the system today, and that it doesn't flow in a natural swoop anymore. So what to do? Well, first of all, you can store more water from Lake Okeechobee instead of sending it east and west to the sea. The obvious way to do that would be to buy out sugar plantations, but there isn't much of that in the CERP, which relies instead on technologically dicey plans to store water underground and in mined-out quarry pits.
Then what? Of course, Miami and Fort Lauderdale are staying put. But in the surviving ecosystem, you can see that the main obstacles to the natural flow are that east-to-west line near the bottom of the system, a highway called the Tamiami Trail, and that diagonal line just above it, the L-67 Levee. Many scientists believe that if you just raised the highway and removed that levee, you'd go a long way toward restoring the sheet flow that is the lifeblood of the ecosystem. But the CERP will not do that for at least 20 years, and then only in part. Even the CERP's best-case scenario in Graph No. 3, while at least similar to the original pattern, would still zip water around the system in weird directions. It is a heavily engineered imitation of the natural water levels, but it is not a natural flow.