habitat - The type of environment in which an organism usually lives.

harvesting - The process of gathering a crop.

hellgrammite - An aquatic macroinvertebrate of the order Megaloptera; also called dobsonfly. Larvae have three pair of segmented legs and four terminal hooks on their abdomen; sensitive to pollution.

herbicide - A toxic substance used to destroy plants.

herbivore - An organism that eats only plants; a primary consumer.

humus - Decayed remains of organisms. The addition of humus to soil enriches it with organic material and increases the capacity of the soil to hold air and water.

hydrilla - Submerged aquatic vegetation (SAV), Hydrilla verticillata; non-native invasive plant with branched stems up to 25 feet long; found in all types of water bodies.

hypothesis - A possible, testable explanation, based on an educated guess and previous observations; a proposed solution to a scientific problem.

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immiscible - Incapable of blending or mixing. In part of the process of converting untreated water into drinkable water, the water must be held undisturbed for a period of time to allow the immiscible pollutants to separate from the water.

impervious - Not capable of being passed through, damaged, or disturbed. (Water is not able to flow through asphalt roads, concrete sidewalks, etc.)

incinerator - An apparatus used for burning waste at very high temperatures; a furnace.

independent variable - A manipulated variable; a factor or condition that changes naturally or is intentionally manipulated by the investigator to observe the effect.

indicator - Any of a variety of substances used to demonstrate the presence, absence, or concentration of a substance.

industrial - Related to the commercial production of goods.

inorganic - Compounds derived from non-living things that do not contain carbon.

interdependent - Organisms that need each other for survival.

invasive species - Organisms that spread, encroach upon, and take over the habitat of native species.

invertebrates - Animals that do not have a backbone.

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Jackson turbidity unit (JTU) - A unit of measure for turbidity (derived from the original "Jackson Tube"). Turbidity is measured by determining the amount of light that is reflected off particles suspended in water.

Japanese honeysuckle - Lonicera japonica, an exotic invasive plant, originally from East Asia, which grows at the wood's edge. image

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kudzu - Pueraria thunbergiana, an exotic invasive bean-like vine, originally from China and Japan. image

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lake - A large inland body of salt or fresh water.

landfill - A huge pit in the ground that is lined with clay or plastic and filled with garbage. Layers of garbage are spread out and alternated with layers of dirt or plastic.

larva (plural larvae) - The immature stage of an organism that usually looks different than the adult form of the organism.

latitude - The angular distance on Earth's surface north or south of the Equator, expressed in degrees, minutes, and seconds.

leeches - An aquatic macroinvertebrate of the phylum Annelida, class Hirudinea; aquatic worms that do not have legs; tolerant of pollution. image

leopard frog - Rana pipiens. Found all over the United States; lives in scrub, desert, ponds, rivers, and meadows, but prefers swamps in the summer; brown or green with small spots on the side; usually 2-3.5 inches long.

longitude - The angular distance on Earth's surface east or west of the Prime Meridian at expressed in degrees, minutes, and seconds.

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macroinvertebrates - Organisms without a backbone that are large enough to be seen with the unaided eye.

marsh - A wetland with few trees and woody shrubs.

mayfly - An aquatic macroinvertebrate of the order Ephemeroptera; larvae have three pair of legs, one pair of antennae, three long tail filaments, and feathery or plate-like gills on their abdomen; sensitive to pollution. image

microbe - A microorganism; a minute life form.

microorganism - An organism of microscopic size; especially a bacterium or protozoan.

midge - An aquatic macroinvertebrate of the order Diptera; a true fly; larvae are very small, often C-shaped and have a spastic, squirming movement; attach themselves to debris with tiny legs; larvae are tolerant of pollution. image

minute of latitude/longitude - A unit of measurement equal to 1/60 of a degree. One minute equals 60 seconds latitude/longitude.

moisture content - Amount of wetness.

mollusk - A marine macroinvertebrate of the phylum Mollusca; a shellfish. image

moratorium - A delay of action; a suspension.

musk thistle - Carduus nutans; an exotic invasive plant, originally from Asia and Europe, which grows in a clearing (meadow or field). image

multiflora rose - Rosa multiflora; an exotic invasive plant, originally from Japan, Korea, or Eastern China, which grows at the wood's edge and in swamp forest (intermittently flooded lowland forest). image

mullet - An edible fish of the family Mugilidae found worldwide in tropical and temperate coastal waters and some freshwater streams.

mussels - Marine bivalve mollusks.

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