The Mississippi River is not known as "Old Muddy" for nothing. By the time it empties out into the Gulf of Mexico (GOMEX), it carries a vast load of sediment, organic material (plants, plant parts, bacteria, algae, fish, protozoa, sewage from animals and possibly humans) and even dissolved chemicals (hydrolyzed plant and animal material, dissolved minerals, and ammonia/nitrates, phosphates, sulfates, etc). It is what is called nutrient laden, and with sufficient oxygen, lots of things could grow in this medium. And did. And then there is all the inorganic particulates (sand, clay, soil), whose surface is usually loaded with nutrients. Even before humans came in a big way to North America, that was the nature of this river, but the intensive farming and urbanization of this region have added more sediment and more nutrients to the river.

Until recently, all this sediment actually had two fates. A large chunk of the river spilled out onto the Mississippi River delta, noticeably after it passed the spot where New Orleans is perilously perched. And then some of it spilled out the end of the river and into the GOMEX, where it tended to tumble down a steep slope in the ocean floor from shallow water (less than 100 meters in depth (about 328 feet)) to much more than this depth, often to 1000 to 3000 feet. And that makes a big difference in the impact on the ocean chemistry and on the living creatures inhabiting that part of the ocean.

The upper 100 meters of the ocean are what is known as "the mixing layer" - this depth may vary a little bit in time and place, but as a general rule, it will do. This layer gets mixed by waves, tides, flows of water entering the ocean, etc, and it tends to have a fairly average composition, especially in terms of dissolved oxygen content. Technically, it is where oxygen, carbon dioxide (the ocean is the ultimate and most effective CO2 stash), nutrients, momentum and temperature are fairly uniform - "well mixed". In cold water (not found in GOMEX surface waters), this O2 content can be 10 ppm, and in warmer waters, this value drops to about 8 ppm. And while it does not sound like much, that is what fish and all kinds of underwater creatures breathe. In this layer, a lot of photosynthesis takes place, because it is also well illuminated, and algae also add O2 into the water column by reacting CO2 and light to make sugars and O2. They also comprise the bottom of the oceanic food chain.

This oxygen is used not only by fish and plankton, but also by bacteria, who tend to be the "recycling" crew, especially of dead creatures, or parts uneaten, or eaten and discarded, by other creatures. If the O2 allowing this recycling to occur is used up, what happens is that the bacteria either shift to a different mode of operation (aerobic to anaerobic) or new types of bacteria step in. For example, Botulism bacteria don't like oxygenated environments, but thrive in places where there is food and no oxygen. Some strains (Type E) produce nasty toxins, killing creatures that eat or ingest them, and then creatures that eat those creatures can also bite the big one. A lot of fish kills and mass killings of fish eating birds result from Type E Botulism. For example, here is an article on this phenomena in the Great Lakes, but the same applies to some parts of the GOMEX - http://birds.suite101.com/article.cfm/type_e_botulism_and_birds.

So, if most of the sediments passing down the Mississippi River are dumped below the mixing layer into the GOMEX, a "dead zone" forms, and given the massive quantities of nutrients involved, it's a really big Dead Zone (technically a "Hypoxic Zone") - see http://www.epa.gov/msbasin/, http://www.snre.umich.edu/newsroom/2007-10-31/u_m_researchers_warn_gulf_... and http://oceanservice.noaa.gov/products/pubs_hypox.html. And, that's what is going on. To make matters worse, the non-organic part of that sediment (sand and clay) would normally replenish the Mississippi River delta, and actually expand the delta. From a fish standpoint, this is a great thing, as the delta is more or less a fish nursery and fish food nursery. All that water that percolates over and through the delta gets its sediment and nutrients filtered, settled, extracted out and/or eaten, and the water flowing into the shallower parts of the coastline is highly oxygenated, largely sediment free and won't contribute to hypoxic zones. And this is really good for GOMEX fishing. So, what's good for the mudbugs (Crayfish) is good for us all. And it makes that portion of our country more hurricane tolerant.

But, right now, the river is funneled though canals (made for oil and gas drilling, pipeline installation, etc) or through the river to its end. The water tends to have a high velocity, which keeps the sediments and attached/associated nutrients in suspension, and they are tend sent off the edge of the oceanic cliff to the bottom of the continental shelf, well below the mixing layer of the GOMEX. This may be great for international shipping, but not much for anything else.

There is a very good solution to this unsustainable mess that originates in the Great Plains (sediments and nutrients). Obviously, not wasting fertilizer applied to crops is helpful, but not all of it will get used by crops, and some escapes, especially via floods. The same goes for topsoil and other kinds of dirt. But some will always get away, and find escape via the Big Muddy. What is really needed is either a set of locks at the end of the Mississippi, or just a zone of shallow water, swamps, wetlands and similar areas (none good for shipping), and for almost all of the river's contents to be dispersed across the delta below New Orleans. Actually, there are several harbors nearby (Mobile, Lake Charles, Orange Texas, Pascagoola, Miss) that could be used to unload and load ocean freighters. The cargoes could then be sent by train to New Orleans, and loaded back onto barges and freighters, for shipment up and down the river. We could even electrify these new express rail lines to the River. And while it would raise transshipment costs a bit, so what, it also makes more jobs, and raises the cost of imports, a lot of which we don't need or want anyway. It's the cost of doing business in a barely sustainable world - the bare minimum that is needed. It would also raise the cost of exports a bit, but for high value added items, no one will notice, and costs for grain and bean exports could be kept minimal. On the plus side, we won't have to bail out the GOMEX coastal communities like New Orleans AGAIN, at a cost of hundreds of billions of non-existent (for now) dollars. And all those fertilizers that wash off millions of farms will get used to make fish in the GOMEX via the delta nursery, instead of this Dead Zone currently the size of Jersey - not the town in England, but the State of New Jersey in our country. If we are not careful, a larger state will need to be selected to describe the size of this wastoid region.

In light of the potential (as of 8-27-08) of Hurricane Gustav, coming after the horrendous tragedy of Katrina and Rita and several other storms that have hit the region in the last few years, fixing the delta and the Dead Zone at the same time would seem to be the smart way to go. And it should be on our national election agenda this year.