Water and the Future of Southeast Florida

If you have driven around the southeastern counties of Florida much, then you have inevitably crossed over, seen and maybe even been dead-ended by canals. They almost always have some water in them, but where is it from, where is it going and for what is it used?

Although the canal system serves as a means of collecting stormwater runoff, its primary use is related to assurance of a sustainable groundwater supply.

The relationship between Southeast Florida’s canal network and its drinking water supply runs in both directions — canals carry water that becomes drinking water, and canals help protect aquifers that supply drinking water. The full picture requires understanding those two complimentary functions.

Direct surface water withdrawals (roughly 25–35% of public supply)

Several major utilities draw directly from canals or canal-connected reservoirs. Palm Beach County’s system is the clearest example: it draws heavily from Lake Okeechobee via the C-51 Canal (West Palm Beach Canal) and related surface water intakes. Some Broward utilities use off-stream reservoirs that are filled from the canal network during high-water periods, essentially banking canal water for dry-season treatment. For these utilities, the canal is the direct supply line to the treatment plant.

Martin County now draws its drinking water entirely from groundwater wells completed in the surficial aquifer and the Floridan Aquifer (the latter treated by reverse osmosis at its two treatment plants). (The St. Lucie River and Estuary used to be a drinking water source in Martin County. Now, because of government decisions to release polluted water from Lake Okeechobee into the St. Lucie watershed, it is highly polluted and at risk of further degradation.)

Aquifer recharge and the role of canals (indirect, management function)

The Biscayne Aquifer — the primary drinking water source for Broward, Miami-Dade, and much of Palm Beach County, serving roughly 6 million people — is recharged principally by two mechanisms: direct infiltration of rainfall through the aquifer’s thin, porous limestone surface, and southward Everglades “sheetflow” percolating downward through the same limestone as it moves across the landscape. The US Geological Survey records show that before development, the broad, slow-moving sheet of water across the Everglades was the major source of recharge to the underlying aquifers, and that this sheetflow remains a major recharge source today wherever it continues to flow.

Management of Aquifer Levels

The canal network plays a secondary but important role in managing aquifer levels rather than primarily supplying recharge volume. During dry season, water released from the Water Conservation Areas into the canal system seeps laterally into the adjacent aquifer, helping maintain water table levels. More critically, coastal control structures on the major canals maintain elevated water levels that hold the saltwater front back from advancing inland — a containment function rather than a recharge function. When canal levels drop during drought or excessive discharge periods, saltwater intrudes.

Of the roughly 900 mgd of public supply demand across the five-county area, about 250–300 mgd comes from direct surface water intakes where canals are the supply source. The remaining 600+ mgd comes from Biscayne Aquifer wellfields that are sustained primarily by rainfall and Everglades sheetflow recharge, with the canal system providing dry-season water level management and coastal saltwater suppression.

My Current Work

I am currently looking at related issues in Martin County. The historic Everglades sheetflow off Lake Okeechobee that recharges the Biscayne Aquifer depends on water moving south — through the landscape, not east through the C-44 to tidal Ocean water. Every gallon discharged east through the C-44 Canal to the St. Lucie Estuary is a gallon that does not move south to recharge the aquifer through the Everglades. Instead, it pollutes and degrades the St. Lucie River and Estuary. (The Lake Okeechobee water is itself greatly polluted.)

Solutions for the Future: In a Nutshell

Enormous and very expensive effort has gone into addressing the challenge of population growth, economic opportunity, robust agriculture, and preservation of a unique natural water balance and supply system in South Florida. However, current plans are demonstrably inadequate to avoid repeated and increased damage to all concerned interests. We need a more effective and innovative engineering effort and politically approved action plan to create an even more wonderful place to live and thrive. I believe we can improve the health of the Everglades, provide more drinking water security, preserve agriculture, save the St. Lucie, and maybe engineer in some added hurricane protection if there were a serious conferral, fresh look at the problem, and committed collaboration of interested parties going forward.

Serious inquiries welcome.