200 • Wetlands: Their Use and Regulation 



Dike — a wall or mound built around a low-lying area 

 to prevent flooding. 



Drainage basin or watershed — the area within which 

 all surface water runoff will normally gather in a 

 single tributary, stream, river, conduit, or other 

 water course. This area is determined by topography 

 that forms drainage divides between watersheds. 



Ecosystem — the system of interrelationships between 

 plants and animals and their environment. 



Emergent — an erect, rooted herbaceous hydrophyte 

 that may be temporarily or permanently flooded at 

 the base, but is nearly always exposed at the upper 

 portion. 



Endangered — nearing extinction; existence of the 

 organism and its environment are in immediate jeop- 

 ardy; distribution is usually restricted to highly specif- 

 ic habitats. 



Estuary — the mouth of a river entering the sea where 

 the current of the river meets the tide and where salt 

 and fresh waters mix. 



Eutrophication — an increase in concentration of nu- 

 trients in rivers, estuaries, and other bodies of water. 

 This increase may be due to natural causes, man's 

 influence, or a combination of both. 



Evergreen — a descriptive term for woody plants that 

 retain their green leaves or needles throughout the 

 year. 



Flood hydrographs — graphs of the time distribution of 

 runoff from a drainage basin which are used to 

 analyze flooding characteristics. 



Flood plain — an area adjacent to a lake, stream, ocean, 

 or other body of water lying outside of the ordinary 

 banks of the water body and periodically inundated 

 by flood flows. 



Flyways — routes followed by migrating birds. 



Food chain — the means by which energy and material 

 are transferred from a producer (a green plant) to 

 herbivores and carnivores. 



General permit — a type of permit that is issued for a 

 category or categories of work or structures when 

 those structures or work are substantially similar in 

 nature and cause only minimal individual and cumu- 

 lative adverse environmental impacts. 



Glacial drift — sediment accumulated as a result of 

 glaciation, under a glacier, at its margins, or beyond. 



Ground water — water that penetrates the Earth's sur- 

 face from precipitation and from infiltration by 

 streams, ponds, and lakes. 



Habitat — the range of environmental factors at a par- 

 ticular location suppxDrting specific plant and animal 

 communities. 



Herbaceous — plant material characterized by the 

 absence of wood. 



Hydrophyte — any plant growing in a soil that is at least 

 periodically deficient in oxygen as a result of excessive 

 water content. 



Indirect impacts — impacts removed from both the 

 direct area and time that development occurs. 



Mangrove — a term denoting any salt-tolerant intertidal 

 tree species. 



Marsh — a common term applied to describe treeless 

 wetlands characterized by shallow water and abun- 

 dant emergent, floating, and submergent wetland 

 flora. Typically found in shallow basins, on lake mar- 

 gins, along low-gradient rivers and in low-energy 

 tidal areas. 



Mitigation — a term that describes the efforts to lessen, 

 or compensate for the impacts of a development proj- 

 ect. 



Mudflat — bare, flat bottoms of lakes, rivers, and 

 estuaries, which are largely filled with organic de- 

 posits, and periodically exposed by a lowering of the 

 water table. 



Nationwide permit — A type of general permit 

 authorized for the entire Nation. 



Organic soil — a "histosol" as defined by the U.S. Soil 

 Conservation Service. In general, a soil is a histosol 

 either if more than 50 percent of the upper 80 cm 

 of soil is organic material or if organic material of 

 any thickness rests on rock or on fragmented material 

 having interstices filled with organic materials. 



Peat — organic soU which has undergone very little de- 

 composition so that plant remains can be identified. 



Permeability — the property of soil or rock to transmit 

 water or air. 



Productivity, gross primary — the rate at which energy 

 is fixed by a particular population or community of 

 producers. 



Productivity, net primary — the rate of increase in the 

 energy that is contained in a particular population 

 or community of producers after the amount of en- 

 ergy that is lost by respiration is deducted from the 

 gross productivity. 



Recharge (ground water) — the percolation of surface 

 water to the water table. 



Riparian — habitats adjacent to rivers and streams. 



Riprap — a bulkhead or other structure constructed of 

 selected rock or concrete and placed so as to dissipate 

 wave energy or collect sand along a shoreline. 



Sedge — a grasslike plant in appearance, of the family 

 cyperaceae, often with a triangular base. 



Shrub — a woody plant that at maturity is less than 6 

 meters tall, usually exhibiting several erect, spread- 

 ing, or prostrate stems and a generally bushy appear- 

 ance. 



Slough — a small body of stagnant water, or a small 

 marshy or swampy tract of land. 



