The South Florida Water Management District did what we asked: they ran the model to find out how much land we need to store, treat, and send clean water south to the Everglades instead of to our rivers. So why, after the district delivered its presentation on scoping this week, do we still not have a realistic answer?

We asked for a number: how many acres? How big is the total footprint for a reservoir that holds at least 240,000 acre-feet (78 billion gallons) and the required stormwater treatment areas (STAs) to clean outflows fast enough not to become a bottleneck that backs up the system when we need it most? After all, the district’s modeling shows that increasing acreage for STAs is the key to cutting discharges to the estuaries.

What we got instead was, Depending on how big the reservoir is, some land might be left over for STAs. And then we got “a reservoir designed to hold between 240,000 and 360,000 acre-feet (as Senate Bill 10 calls for) would likely need to be accompanied by 6,000-9,000 acres of STAs.”

That’s not nearly enough, but even that low-ball estimate can’t be wedged into the footprint presented by the district.

Although its spokespeople mentioned the ability to send an additional 1.3 million acre-feet south in wet years, they showed only a graph of an average year–when we don’t have discharges. And it showed that an impossible 20-foot-deep reservoir with only four acres left over to treat the water still falls short of their arbitrary average-year target. Even on the district’s own chart, even if we could build a reservoir with hundred-foot-high banks, the numbers don’t work.

Thanks to independent experts, we have a good sense of the numbers that do work: A 240,000 acre-foot reservoir needs about 13,000 acres of STAs to clean water fast enough to keep flowing efficiently (roughly one thousand acres for every 20,000 acre-feet, or 6.5 billion gallons). SFWMD knows this, too–the ratio is the key to the state’s 2012 Restoration Strategies plan. Why do this week’s assumptions include less than half that much land for STAs?

If the Restoration Strategies figure is right, anything less than 13,000 acres for STAs would undermine SB10’s goal of reducing discharges to the Caloosahatchee and St Lucie estuaries, wasting taxpayer money on a failed solution.

This is where we need your help: Maps show that enough public land is still available to make this project work, including substantial acreage not shown in the presentation. (And it looks like private landowners may be willing to help, too.)

Please The window for public input closes in November 22nd, so this is your last chance to be heard on getting the project’s footprint right. With enough land for treatment, it works. Without it, nothing changes.