18 



moccasin, garter, queen, mud and swamp snakes. In bot- 

 tomland wetlands of the South, copperheads and cane- 

 brake rattlesnakes can be found as well as northern 

 brown, garter, rough green and rat snakes (Wharton and 

 Kitchens 1982). The San Francisco garter snake, an en- 

 dangered species, also requires wetlands for survival 

 (Williams and Dodd 1979). 



Nearly all of the approximately 190 species of amphib- 

 ians in North America are wetland-dependent, at least for 

 breeding (Clark 1979). Every freshwater wetland in the 

 U.S., except in the Arctic tundra, probably has some 

 frogs. Common frogs include the bull, green, leopard, 

 mink, pickerel, wood and chorus frogs and spring peep- 

 ers. Many salamanders use temporary ponds or wetlands 

 for breeding, although they spend most of the year in 

 uplands. Numbers of amphibians, even in small wet- 

 lands, can be astonishing. For example, 1,600 salaman- 

 ders and 3,800 frogs and toads were found in a small gum 

 pond (less than 100 feet wide) in Georgia (Wharton 

 1978). 



Environmental Quality 

 Values 



Besides providing homes for fish and wildlife, wet- 

 lands play a less conspicuous but nonetheless important 

 role in maintaining high environmental quality, especial- 

 ly in aquatic habitats. They do this in a number of ways, 

 including purifying natural waters by removing nutrients, 

 chemical and organic pollutants, and sediment and pro- 

 ducing food which supports aquatic life. 



Water Quality Improvement 



Wetlands help maintain good water quality or improve 

 degraded waters in several ways; ( I ) removing nutrients. 

 (2) processing chemical and organic wastes, and (3) re- 

 ducing sediment loads of water. Wetlands are particularly 

 good water filters because of their location between land 

 and water. Thus, they can both intercept runoff from land 

 before it reaches the water and help filter nutrients, 

 wastes and sediment from flooding waters. Clean waters 

 are important to man as well as to aquatic life. 



First, wetlands remove nutrients, especially nitrogen 

 and phosphorus, from flooding waters for plant growth 

 and help prevent eutrophication or overenrichment of nat- 

 ural waters. It is, however, possible to overload a wetland 

 and thereby reduce its ability to perform this function. 

 Every wetland has a limited capacity to absorb nutrients 

 and individual wetlands differ in their ability to do so. 



Wetlands have been shown to be excellent removers of 

 waste products from water. In fact, certain wetland plants 

 are so efficient at this task that some artificial waste 

 treatment systems are using the.se plants. For example, 

 the Max Planck Institute of Germany has a patent to 



create such systems, where a bulrush is the primary waste 

 removal agent (Sloey, et al. 1978). 



Numerous scientists have proposed that certain types 

 of wetlands be used to process domestic wastes. Some 

 wetlands are already used for this purpose. The Brillion 

 Marsh in Wisconsin has received domestic sewage since 

 1923. This cattail marsh on the average removed 80% of 

 biological oxygen demand, 86% of coliform bacteria, 

 51% of nitrates, 40% of chemical oxygen demand, 44% 

 of turbidity, 29% suspended solids and 13% of total phos- 

 phorus. After passing through Brillion Marsh, there was a 

 significant improvement in water quality (Boto and Pat- 

 rick 1979). 



Perhaps the best example of the importance of wet- 

 lands for water quality improvement is Tinicum Marsh 

 (Grant and Patrick 1970). Tinicum Marsh is a 512-acre 

 freshwater tidal marsh lying just south of Philadelphia, 

 Pennsylvania (Figure 17). Three sewage treatment plants 

 discharge treated sewage into marsh waters. On a daily 

 basis, it was shown that this marsh removes from flood- 

 ing waters; 7.7 tons of biological oxygen demand, 4.9 

 tons of phosphorus, 4.3 tons of ammonia, and 138 

 pounds of nitrate. In addition, Tinicum Marsh adds 20 

 tons of oxygen to the water each day. 



Swamps also have the capacity for removing water 

 pollutants. Bottomland forested wetlands along the Al- 

 covy River in Georgia filter impurities from flooding 

 waters. Human and chicken wastes grossly pollute the 

 river upstream, but after passing through less than 3 miles 

 of swamp, the river's water quality is significantly im- 

 proved. The value of the 2,300-acre Alcovy River 

 Swamp for water pollution control was estimated at $1 

 million per year (Wharton 1970). 



Wetlands play a valuable role in reducing turbidity of 

 flooding waters. This is especially important for aquatic 

 life and for reducing siltation of ports, harbors, rivers and 

 reservoirs. Removal of sediment load is also valuable 

 because sediments often transport absorbed nutrients, 

 pesticides, heavy metals and other toxins which pollute 

 our Nation's waters (Boto and Patrick 1979). Depres- 

 sional wetlands should retain all of the sediment entering 

 them (Novitski 1978). In Wisconsin, watersheds with 

 40% coverage by lakes and wetlands had 90% less sedi- 

 ment in water than watersheds with no lakes or wetlands 

 (Hindall 1975). Creekbanksof salt marshes typically sup- 

 port more productive vegetation than the marsh interior. 

 Deposition of silt is accentuated at the water-marsh inter- 

 face, where vegetation slows the velocity of water caus- 

 ing sediment to drop out of solution. In addition to 

 improving water quality, this process adds nutrients to the 

 creekside marsh which leads to higher plant productivity 

 (DeLaune. et al. 1978). 



The U.S. Army Corps of Engineers has investigated 

 the use of marsh vegetation to lower turbidity of dredged 

 disposal runoff and to remove contaminants. In a 50-acre 

 impoundment near Georgetown, South Carolina, after 

 passing through about 2,000 feet of marsh vegetation, the 

 effluent turbidity was similar to that of the adjacent river 



