💧Key Terms - Watersheds💧

Aerobic – Containing oxygen.  For instance: conditions that contain oxygen, organisms that require oxygen to survive or any chemical/biological processes that occur in the presence of oxygen. 

Algae – Members of a large group of primarily aquatic organisms that contain chlorophyll and other pigments and can carry out photosynthesis, but lack true roots, stems, or leaves and range from single cells to large multicellular structures.  Examples of algae include seaweed, kelp, dinoflagellates, and diatoms.   

Algal Bloom – The rapid growth of algae in a system due to excessive amounts of nutrients and the appropriate physical and chemical conditions. 

Anaerobic – Lacking oxygen.  For instance, conditions that lack oxygen, organisms that can survive without oxygen, and any chemical or biological processes that occur without oxygen. 

Aquifer – A stratum of rock or soil that contains groundwater. 

Bed Load- Sediments and organic matter which moves along the bottom of a stream during periods of high flow. 

Benthic Macro Invertebrates – animals without backbones or internal skeletons that live on or near the bottom of a water body. Their presence is a good indicator of water quality.

Benthos – All organisms living at or near the bottom of an aquatic habitat. 

Confluence – The point at which two rivers/streams/etc. flow together. 

Decomposition – The breakdown of organic substances by microorganisms. 

Delta- A geographic feature formed at the mouth of a river, where the river flows into an ocean, sea, estuary, lake, or reservoir. Deltas are formed from the deposition of the sediment carried by the river as the flow leaves the mouth of the river. 

Dissolved Oxygen – A measurement of the amount of oxygen present in the water column.  Dissolved oxygen is important for aerobic organisms and proper biological functioning.  Less than 5 parts per million of oxygen in water can cause stress to aquatic organisms.  The lower the oxygen concentrations, the greater the stress.  

Dissolved Load- All the soluble materials which are carried to the ocean by the water in a stream or river. 

Ecosystem – The network of a biological community and its surrounding interconnected physical and chemical environment. 

Erosion – The movement of weathered materials (see weathering) by gravity, wind and water. The rate of erosion may be increased by land-use activities. 

Estuary - A coastal area where freshwater from rivers and streams mixes with saltwater from the ocean.  Bays, sounds, and lagoons along coasts may be estuaries.  Segments of rivers and streams connected to estuaries are considered part of the estuary. 

Ephemeral Stream- A stream which flows during and immediately after a precipitation event but stops flow at the surface during dry periods. 

Eutrophication – Process by which a water body undergoes an increase in dissolved nutrients, often leading to algal blooms, low dissolved oxygen, and changes in community structure.  This process occurs naturally over time, but can be accelerated by human activities that increase nutrient inputs into aquatic ecosystems. 

Floodplain – Area of land on each side of a stream channel that is inundated periodically by flood waters. 

Groundwater – Water occurring beneath the earth’s surface, typically in aquifers, that supplies wells and springs, and is a key source of drinking water. 

Habitat – An area with specific physical and environmental conditions in which a particular plant or animal lives. 

Hydrology – Movement and distribution of groundwater and surface water in a system. 

Hypoxia – Low dissolved oxygen concentrations in aquatic environments. 

Impervious Surface – A surface that does not allow water to penetrate.  Examples of impervious surfaces include asphalt, rooftops, and concrete. 

Infiltration – The process by which a liquid seeps into the earth. Occurs in permeable surfaces only.

Meander – A curve in a river or stream. 

Nutrients – Substances, such as nitrogen and phosphorous, required by plants and animals for growth.  In some circumstances, excessive nutrient additions to surface waters may result in excessive algal/plant growth and, subsequently, the accumulation and decay of increased organic matter. (See Eutrophication)

Oxbow Meander- An extreme meander on a river. Indicates a mature or old river basin.

Oxbow Lake- A lake in the shape of an oxbow which is adjacent to an old river. Forms when banks along an extreme meander are breached during floods.  

Perennial Stream – A stream that flows continuously throughout the year. 

Pools - A section of a stream with slow-moving, deep water.  In natural streams pools and riffles are alternating. 

Riffle – A section of a stream with fast-moving, turbulent, shallow water with a rocky bottom.  In natural streams pools and riffles are alternating. 

Riparian – Of, relating to, living on, or located on the banks of a watercourse such as a river, stream, lake, etc. 

River Basin – Area encompassing all the land drained by streams and creeks flowing downhill into a major river.  All water that falls within the basin flows into these streams and rivers. 

Runoff – Water flowing across the land that does not infiltrate the soil, but drains into surface or ground waters, or when rainfall exceeds the infiltration capacity of the land. 

Suspended Load – Organic and inorganic particles suspended in the water column and carried by swift moving water.  The presence of suspended solids in water may reduce the amount of light reaching the water column, clog the gills of fish and other animals, and are often associated with toxic contaminants that bind to particles. 

Transpiration- water vapor released from plants to the atmosphere.

Tributary – A stream or river that feeds into a larger stream, lake, or river. 

Water Cycle – The cycle in which water evaporates from surface waters, condenses into clouds, and falls again to the earth as rain or other forms of precipitation. The movement of water in the biosphere.

Water Table – The depth at which the ground is saturated with water. 

Watershed - The entire land surface (and associated ecosystem) which drains into a particular body of water. 

Weathering- The wearing away of rock and soil due to wind, water, ice, or other physical, chemical, or biological forces. Sediments are produced by weathering. These weathered materials (sediments) are transported by gravity, wind or water by a process called erosion. 

Wetlands – Areas that are frequently inundated or saturated with water. Wetlands may include bogs, swamps and marshes. Important for infiltration and purification of surface runoff.