Major Threats to a Wetland

Humans have been the major threat to wetlands.  Agriculture, industrial development, urbanization and suburban sprawl have caused the greatest losses of freshwater wetlands. 

It is not uncommon for farmers to drain a wetland area and then plant crops on the land.  It's important to note that crops tend not to grow as well in some wetland soil types as opposed to surrounding farm land.  Nationwide, agriculture is responsible for approximately 80% of all wetland losses.  However, agriculture is no longer expanding on the Gulf Coast, and very little of the current loss can be attributed to it.  Riceland agriculture is actually beneficial, because of the flooding that is involved with it, provides some additional wetland habitats. 

People drain and fill in wetlands so that they can build on the land.  As cities and towns expand and more industries are constructed, the pressure to drain wetlands will increase.  On the Texas gulf coast, the biggest current source of loss for freshwater coastal wetlands is from urban sprawl.  Land subsidence caused by the mining of oil, gas and groundwater has been the primary source of saltwater wetland loss.  Subsidence causes the land surface to drop, which can then become flooded if the surface is already very near to the sea level.  Subsidence-induced flooding has drowned many wetlands, especially and around large coastal cities such as Houston.

Wetlands are the kidneys of Earth.  They act as a sponge that clean up water by filtering out some kinds of pollutants found in the water.  However, too much pollution generated by industry, agriculture, or urban areas can kill plants and animals living in the wetlands.  Each year in North America over 700,000 acres of wetlands are lost due to agriculture, development, and pollution.  

Even though wetlands can reduce the impact of some pollutants, too much pollution will negatively impact the wetland.  The quality of a wetland is dependent on the water flowing into them... and the pollutants that the water carries with it from activities in the watershed.

Runoff that contains pollutants is called nonpoint source pollution.  In addition to the potential  of runoff polluting wetlands, it also can pollute other surface waters such as lakes,  rivers, and, oceans.  Eventually it can reach groundwater, which is often used for drinking water.

Source:  Texas Coastal Wetlands Guidebook, by Daniel W. Moulton and John S. Jacob, Texas Sea Grant Publication TAMU-SG-00-605, p.3.

Source:  United States Environmental Protection Agency, Welcome to the Wetlands, February 1997.  

Source:  Wetlands:  A Key Link in Watershed Management; A Guide for Watershed Partnerships; Know Your Watershed Campaign and the Conservation Technology Information Center (CTIC); p. 5.