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The term water quality involves a broad range
of issues important to the living resources and human uses of bays or
estuaries and surrounding areas. These include, but are not limited to,
properties such as salinity, fecal coliform and other pathogens, toxins,
metals, nutrients, oxygen levels, sediment load and associated
characteristics, as well as, processes that affect these traits.
Mobile Bay's water quality is highly influenced by its natural geographic
location, weather patterns of the watershed, and human uses. The Mobile
Bay watershed or drainage system includes over two-thirds of Alabama and
portions of Georgia, Tennessee, and Mississippi, making it the nation's
sixth largest in area and fourth largest in discharge volume. As a result,
urban and agricultural development in the Bay's surrounding areas and in
areas far outside the coastal region impact Mobile Bay's water quality
characteristics.
Due to the large discharge volume of freshwater inputs entering Mobile
Bay, it has been estimated that approximately 4.7 million metric tons of
sediment are deposited into the Bay annually. This material has a high
percentage of silt and clay which can create a variety of environmental
problems. Mobile Bay also receives more that 42,000 tons of nitrogen each
year, which is a nutrient of concern in most coastal waters. Only 14%
originate in the area right around the Bay; 86% comes from upstream
sources. Nutrient over-enrichment can lead to problems such as low oxygen
levels. In 1989, there were some 150 point sources of pollution discharge
permitted in the Bay's vicinity, totaling around 240 million gallons per
day of liquid waste. A "point source" is any discernible, confined and
discrete conveyance, like a pipe, ditch, tunnel, well, conduit, container,
vessel, truck, train, feed lot, etc., from which pollutants are, or may
be, discharged. The good news is that the total in 1970 was over 830
million gallons per day. That's a reduction of almost 70%.
There are many examples of water quality issues that should concern all of
us. Only a few are given here. If you would like to know more information
or become involved with the Mobile Bay National Estuary Program, please
call our office, (251) 431-6409 or email us.
Source: Dauphin Island Sea Lab
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