raceme - A particular type of arrangement of flowers on a main axis or stem. Flowers with a raceme arrangement have single stalks arranged along a common axis (e.g., lily-of-the-valley).

rampant - Widespread; extending unchecked; unrestrained.

random - Having no particular pattern or order.

rapids - An extremely fast-moving part of a river, caused by a steep descent in the riverbed.

recycling - The process by which wastes can be reused or converted into other materials or products. The process by which materials and substances are reused.

refuse - Waste products, including both wet and dry materials.

residential - Land used for human dwellings and activities.

respiration - The process that involves the transfer of oxygen to cells and the breakdown of food to release energy. In complex animals, respiration involves the intake of oxygen and the discharge of carbon dioxide.

restoration - The act of putting something back to a prior condition.

riffle - A rapid, turbulent flow of water over a shallow area in a stream. Riffles add oxygen to the water as water is churned, and provide habitat for many invertebrates. image

riffle beetle - An aquatic macroinvertebrate of the order Coleoptera; larvae are specially adapted to cling to smooth rocks in fast-flowing water (riffles); sensitive to pollution.

riparian area - The land adjacent to streams, rivers, or other bodies of water that directly affects, or is affected by, the water. A unique habitat that exists in mutual balance with the river channel. image

river - A large natural stream of water emptying into an ocean, lake, or other body of water, and usually fed along its course by converging tributaries.

river basin - The land area drained by a river and its tributaries; a watershed.

rubbish - Refuse, trash, waste. image

runoff - That part of the precipitation, snow melt, or irrigation water that appears in uncontrolled surface streams, rivers, drains, or sewers. Runoff may be classified according to speed of appearance after rainfall or melting snow (direct or base runoff) or according to source (surface runoff, storm interflow, or ground-water runoff).

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sample - A portion, piece, or segment regarded as representative of a whole.

sand - Suspended sediment or bed material with a particle-size of 0.062-2.0 mm in diameter. image

scrubland - A growth or tract of stunted vegetation.

scuds - An aquatic macroinvertebrate; an amphipod of the phylum Arthropoda, class Crustacea; have many appendages and two pair of antennae; are very fast swimmers; look like shrimp; somewhat sensitive to pollution. image

secondary consumer - An organism that feeds on primary consumers; a carnivore.

second of latitude/longitude - A unit of measure equal to 1/60 of a minute latitude/longitude.

sediment - Loose materials such as rock fragments and mineral grains that have been transported by wind, water, or glaciers.

sediment load - Total sediment in a sample of water. There are three categories of sediment: suspended load, dissolved load, and bed load.

sediment particle size - The diameter, in millimeters, of sediment. Particle-size classifications are: 0.00024-0.004 mm (clay); 0.004-0.062 mm (silt); 0.062-2.0 mm (sand); 2.0-64.0 mm (gravel). image

sedimentation - The action or process of forming or depositing sediment.

sensitive to pollution - Organisms that are easily harmed by low levels of pollutants. They are good indicators of clean water because they cannot survive in polluted water.

sewage - Solid and liquid human and animal wastes.

shellfish - An aquatic animal having a shell or shell-like exoskeleton (i.e. mollusk, crustacean). image

silt - Suspended sediment or bed material with a particle-size of 0.004-0.062 mm in diameter.

siltation - To become choked or obstructed with silt.

snapping turtle - A freshwater turtle of the family Chelydridae. Snapping turtles have a rough shell and powerful hooked jaws.

soil compaction - A process that occurs as soil is squeezed repeatedly, decreasing the air spaces between soil particles and making the soil very hard.

sow bugs - An aquatic macroinvertebrate; an isopod of the phylum Arthropoda, class Crustacea; somewhat sensitive to pollution. image

spawn - To produce or deposit eggs.

species - A group of organisms that share similar characteristics and can interbreed with one another to produce fertile offspring.

spring peeper - Hyla crucifer. A small brownish tree frog, found in eastern North America, having a shrill high-pitched call.

speed (stream) - The rate that water flows. image

stewardship - To be responsible for managing property or resources; the individual's responsibility to manage his/her life and property with proper regard for the rights of others.

stonefly - Aquatic macroinvertebrate; order Plecoptera; nymphs have three pair of legs, a pair of antennae, and two long tail filaments; typically found on or near stones in the stream; sensitive to pollution. image

stream - A body of water flowing in a natural channel and containing water at least part of the year.

striped bass - Roccus saxatilis. A food and game fish of North American coastal waters, having dark longitudinal stripes along the sides.

submerged aquatic vegetation (SAV) - Benthic plants that grow totally under water. (e.g., .hydrilla, coon tail, wild celery, eel grass). image

suburban - The area or communities surrounding a major city.

suspended load - Sediment that contains organic and inorganic particulate matter suspended in and carried by moving water.

suspended sediment - Very fine soil particles that remain in suspension in water for a considerable period of time without contact with the bottom, due to the upward components of turbulence and currents.

swamp - A wetland that contains trees and woody shrubs.

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