Nitrogen and phosphorus pollution ranks as one of the top causes of degradation in some U.S. waters for more than a decade. Large amounts of nitrogen and phosphorus lead to regional water quality problems like algal blooms, hypoxia and declines in wildlife habitat.

“Aerobic conditions” in water ways signifies the presence of oxygen in a hydrological system.  The natural cycles of the water feature may be more or less in balance until an excess of nitrate, or nitrogen, and/or phosphate enters the system. At this time, water plants and algae begin to grow more rapidly than normal. There is also an excess die off of plants and algae as sunlight is blocked at lower levels. Bacteria try to decompose the organic waste, consuming the oxygen, and releasing more phosphate which is known as “recycling or internal cycling”. Some of the phosphate may be precipitated as iron phosphate and stored in the sediment where it can then be released if anoxic conditions develop.

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Municipal Technologies | Wastewater Management | US EPA.

Managing Wetlands to Control NPS

A large resource of technologies from the EPA site. This applies to a broad range of solutions for treatment wetlands and other infrastructure.

Since construction of the MRGO and other canals that are intended to increase access and improve navigation in the area, average salinity levels have risen in coastal Louisiana.   The MRGO, or Mississippi River Gulf Outlet, breaches the barrier islands, which serve to shelter coastal wetlands thus exposing once protected areas to the full effects of salt intrusion.  In 1989, the MRGO canal was 3 times larger in width than at original construction due to coastal erosion that resulted from activity along the canal.  Although the MRGO has been closed, it is still conveying salt water into the wetlands and salinity levels continue to rise, though not as rapidly.

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reaching for the surface

Salt domes begin as salt deposits in the sea that after a period of time, are cut off from the main body of water. The surrounding water evaporates and allows sediments to cover the salt pans. Because the salt was less dense than the surrounding sediments, it pushed its way toward the surface, creating roughly circular topographic prominences with desirable resources beneath its surface; salt and petroleum. The surfaces range from 23-52 meters above sea level.

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Overuse and improper filtration of fertilizer in agricultural areas within the Mississippi River basin is causing hypoxia in Gulf of Mexico south of the Mississippi River delta. Excess levels of nitrogen and phosphorus cause heavy algal blooms. When these microorganisms decompose, oxygen is depleted from the water negatively impacts sea life off the coast of Louisiana. This dead zone has doubled in size over the last twenty years and has harmed the commercial shellfish and shrimping industry in the areas.

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The Mississippi River Delta Basin comprises approximately 521,000 acres of land and shallow estuarine water area in the active Mississippi River delta. Approximately 83 percent of this area, or 420,000 acres, is open water. The 101,100 acres of land in the basin are characterized by low relief, with the most prominent features being natural channel banks and dredged material disposal areas along the Mississippi River, its passes, and man-made channels. Coastal marshes make up approximately 61,650 acres or about 61 percent of the total land area in the Mississippi River Delta Basin. Eighty-one percent of this marsh is fresh, 17 percent is intermediate, and 2 percent is brackish-saline.

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The word “algae” refers to a large group of organisms, but typically account for plant-like aquatic organisms that generate energy through photosynthesis, but lack roots, stems, leaves and vascular tissue. It is an organism that exists worldwide, occurring in both fresh and salt waters; and is an essential part of many oceanic animal’s diet. Unicellular algae are known as microalgae and have an extraordinary potential for cultivation, “They can be cultivated under difficult agro-climatic conditions and are able to produce a wide range of commercially interesting byproducts such as fats, oils, sugars and functional bioactive compounds.”(http://www.oilgae.com/algae/algae.html). Today, experimentation and research is done mostly in the private sector, but small scale tests’ results have begun to raise the notion and idea that perhaps algae biofuel might be the alternate fuel that has the most potential to replace automobile diesel usage.

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Delta definition:  Coastal accumulations, both subaqueous and subaerial, of river-derived sediments adjacent to, or in close proximity to, the source stream, including the deposits that have been secondarily molded by various marine agents, such as waves, currents, or tides.
In layman’s terms: A landform created at the mouth of a river where the river empties into an ocean, sea, estuary, lake, reservoir, or flat arid area.  When the flow enters the standing water, it is no longer confined to its channel and expands in width. This flow expansion results in a decrease in the flow velocity, which diminishes the ability of the flow to transport sediment. As a result, sediment drops out of the flow and deposits.

Deltas occur throughout the world, except at the poles.  They all have three characteristics in common:
1. The presence of a large catchment, or drainage, basin (the area where all run-off water drains to the river).  The top 30 river deltas all have catchment basins in excess of 1,000,000 sq km.

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WATER FLOW

Speed: At the headwaters of the Mississippi, the average surface speed of the water is near 1.2 miles per hour – roughly one-third as fast as people walk. At New Orleans, on 2/24/2003, the speed of the river was 3 miles per hour. 

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Humans have­ attempted to conquer the problems of changing water levels for thousands of years. One of the oldest weapons they’ve used against the rivers and oceans is the levee, also known as a dike. A levee is simply a man-made embankment built to keep a river from overflowing its banks or to prevent ocean waves from washing into undesired areas.

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