On the Everglades Part 2: What's wrong with Lake O water?
The tagline of New Yorker writer and comedian Andy Borowitz used to be that there's a fine line between social media marketing and wasting your life. He's got a point. You wonder who is really listening in when you aim your Star Trek communicator at the ether. Every once in a while, however, you do see yourself making a difference. At the request of a friend, I engaged in a pretty lengthy exposition of water quality issues in Southwest Florida on her Facebook page. I got a very nasty response from one other person; I later re-explained the points on which this woman was confused and got a backhanded thank you. I had criticized local reporting. The next day, the reporting was better. I'm not certain whether I had just spoken with the reporter or an associate, but everything on which I had corrected her was correct in the new story.
So, lesson learned: when there is a lot of misleading or outright false crap in the media (social or traditional), it does sometimes make sense to correct it. Confusion leads to inaction on the part of the public, and in saving the Everglades, a lot of action is needed.
And thus I come to today's post. I am going to skip the politics and leave that for a separate post, focusing instead on the environmental science. For those new to the issues of Everglades ecology, please read my part 1 first, which focused on the geography needed to understand these issues.
The blogosphere, local media and social media have recently been filled with claims that we are all being poisoned by the "pesticides" coming from Lake Okeechobee water releases. False. The data: in 2007, after a year of very low rainfall, Lake O was low enough in level that the muck that had accumulated on the bottom could be dredged. Disposing of this muck was a problem, as the arsenic levels were four times higher than that allowable for use in commercial, agricultural or residential properties. No other pollutant tested was a problem; indeed, mercury levels were way lower than in the Everglades. Arsenic was the residue of very old, then-banned, herbicides (weed killers) that had been common on land that had been in agricultural production for a long time, e.g., Big Sugar's sugarcane fields and orange groves.
So, how did this stuff get into Lake O? Up to 2014 when it was deemed a violation of the federal Clean Water Act (a bundled class action lawsuit was decided by NY courts), Big Sugar was taking water from Lake O for irrigation, allowing it to pick up residue of everything they dumped on their fields, and then returning it directly to Lake O ("back pumping"), where it mixed with water used for drinking in South Florida. (In a major loophole, they are still allowed to do this for "flood control," but in any year other than this one, that loophole has been near-irrelevant.) With it came a lot of dirt, and that all sunk to the bottom.
But does this matter? The problem with even trace pollutants is that they bioaccumulate: plants/algae incorporate some of it, an herbivore eats the plant/algae, a first-order carnivore eats the herbivore, a second-order carnivore eats the first, etc. Because of losses in an energy pyramid, roughly ten times the biomass on a lower level is needed to support a higher level. If all of the pollutant accumulates (common with fat-soluble pollutants), every level ten-fold magnifies the concentration of pollutants in animal tissues.
The best study I've seen of whether bioaccumulation is occurring in Lake O was published in 2004 in Environmental Monitoring and Assessment. This study looked at the top predator in the ecosystem: the Florida gar (a type of fish). If arsenic was a problem at all, it should be at its worst in this species. The levels were so low that it was considered safe for human consumption in all tissues except the liver (and who eats fish liver?) which would have been barely over the level considered safe. No other metal tested was a problem.
The popular press tends to ignore dosages (trivial, trace levels of most pollutants don't do anything), the chemical and biological degradation these pollutants undergo in the environment, and sequestering. A little arsenic stuck in the muck was apparently irrelevant to the ecosystem. Indeed, a 2007 study of water quality in the entire region including outfall directly coming from lands owned by US Sugar found no pesticide tested exceeded standards for safe drinking water.
Bottom line: ignore the scaremongering that sounds like boilerplate lifted from some bumper sticker. Focus on what's important coming out of Lake O water when worrying about the problem of releases (and of course, the lack of water going to the Southeastern Everglades). Three things on which to focus: dirt, phosphates and nitrates.
The pictures of Lake O water heading through the Caloosahatchie have been dramatic. They are brown. That brown is mud. In the winter, the Caloosahatchie is generally clear. Clear water allows light to penetrate, facilitating photosynthesis of submerged aquatic vegetation. In the river, Valisneria americanum is the key plant species on which the ecosytem is based; in the estuaries and near-waters of the Gulf, it is several species of seagrass. Block the light, block photosynthesis, many things die.
Phosphates come mainly from fertilizer used in agriculture (and thus Big Sugar is indeed implicated with high levels in Lake O), mining of phosphates (right where I live is a huge area for that) and municipal sewage. The Everglades is traditionally very low in phosphate, and the ecosystem evolved for growth in truly trivial levels. Flooding it with phosphates leads to overgrowth of nuisance algae and bacteria; the native species suffer. With water heading in canals directly into Florida Bay, Biscayne Bay, and the coastal coral reefs, phosphate loading was highly damaging. The direct dumping of sewage and the deplorable state of many septic systems on the east coast of Florida were certainly also huge contributors to this problem.
The solution: funding and implementing the Everglades Restoration Project (and fixing city sewer and septic systems). If water flowed as it would have naturally prior to building Tamiami Trail, it would pass very, very slowly over the "River of Grass," the sawgrass stands that make up much of the Florida Everglades. These plants are fantastic at removing phosphates (and nitrates) from the water. Clean, fresh water will then recharge the Everglades.
But this is all irrelevant to the noise made by cities downstream from Lake O on the Caloosahatchie. These river ecosystems are nitrate-limited, not phosphate-limited. The addition of excess nitrates will fuel the growth of nitrate-limited organisms. The problem is not the red tide algae, Karenia brevis. These blooms start 100 miles offshore in the Gulf of Mexico. Coastal nutrient overloading is not directly relevant to what starts these blooms. It may, in some cases, feed the continuation of the blooms and make the toxic algae stay longer than it would have otherwise, but it's not the source of the problem.
It has, however, at times led to blooms of the toxic cyanobacteria (blue-green algae) called Microcystis. Some summers, we have seen neon streaks in the surface waters of the Caloosahatchie--that's Microcystis. Microcystis make a toxin called microcystin, which in areas truly overgrown with the cyanobacteria can cause problems with livestock or people who are exposed to the water. In China, for example, where many areas don't remediate this problem at all, microcystin exposure is one of the leading causes of colorectal cancer in humans.
But, it was not a problem this year. It's the winter. Microcystis blooms have only occured here when the water is warmer. That's a summer problem. That's usually when Lake O releases occur, because that's the rainy season, but not this year, in which we've had no dry season.
Elsewhere, Microcystis blooms occur when natural competitors are wiped out. In the Great Lakes, for example, ballast water from New Zealand ships introduced zebra mussels that ate everything except for Microcystis. Microcystis thrived, causing huge problems, that are only just now coming under control.
Excess nitrates will also cause the growth of bacteria. In lake ecosystems, excess nitrates fuel algae blooms, which then decay, feeding bacteria, whose respiration removes all dissolved oxygen. Fish suffocate and die. A dead zone results. One also sees this problem in the Mississippi Delta, as "The Big Muddy" picks up top soil from the entire river and deposits it, along with all the nitrates, into the area of the Gulf of Mexico that is now a dead zone.
But those generally aren't the bacteria that close beaches. The Saint Lucie Estuary has indeed had brown water due to Lake O discharges. But it is the poopy water (to use the erudite, scientific term) coming from municipal sewage discharges that puts enterobacteria into the ecosystem. News flash: it's your poop and animal poop closing those beaches, not the capitalists running Big Sugar. Sure, the nitrates will contribute to their growth, but a lot more of that is coming from the city sewage too.
So, the mayors of towns like Sanibel and Fort Myers see brown water, see tourists leaving (even as the water has been declared safe in which to swim), and blame the Water Management District for the Lake O releases. Yes, it is their fault the water is brown. But the hysteria over pesticides, arsenic, nutrient overloading? Give me a break. How about they tend to the overdevelopment that leads to erosion in their towns and better maintain their waste management infrastructure?
Rather than pointing fingers, the real solution is to complete the Everglades Restoration Project, so the water flows through the Everglades, not through the Caloosahatchie, Saint Lucie and Indian Rivers. Why the water isn't already flowing is a matter of politics. And that's a topic for another post.