| Acidic | The condition of water or soil that contains substances which lowers the pH below 7.0. |
| Acidification | Process by which the acidity of the water is raised (pH is lowered) by the addition of acid. |
| Aerobic | Occurring, acting, or living only in the presence of oxygen. |
| Algae | Simple single-celled (phytoplankton), colonial, or multi-celled, mostly aquatic plants, containing chlorophyll and lacking roots, stems and leaves. Aquatic algae are microscopic plants that grow in sunlit water that contains phosphates, nitrates, and other nutrients. Algae, like all aquatic plants, add oxygen to the water and are important in the fish food chain. Algae is either suspended in water (see PHYTOPLANKTON) or attached to rocks and other substrates (see PERIPHYTON). Algae are a essential part of the lake ecosystem and provides the food base for most lake organisms, including fish. Phytoplankton populations vary widely from day to day, as life cycles are short. |
| Algal bloom | A heavy growth of algae in and on a body of water. This usually is a result of high nitrates and phosphate concentrations entering water bodies from fertilizers and detergents. |
| Alkalinity | or acid neutralizing capacity: Describes the ability of the water to buffer any acid inputs. This is typically low in NH lakes due to the lack of calcium in our soils and bedrock which underlies our lakes. |
| Anaerobic | In the absence of oxygen (also anoxic). |
| Anoxia | No oxygen present |
| Bedrock | The solid rock beneath the soil and superficial rock. A general term for solid rock that lies beneath soil, loose sediments, or other unconsolidated material. |
| Benthic | Located on the bottom of a body of water or in the bottom sediments. |
| Bioaccumulation | The process by which the concentration of a substance is increased through successive links in a food chain resulting in toxic concentrations at the top of the chain. |
| Biological Production | Total amount or weight of living plants and animals. |
| BMPS | Best Management Practices. An engineered structure or management activity that eliminates or reduces adverse environmental effects of pollutants. |
| Buffer Strip | Grass or other erosion preventive vegetation planted between a waterway and an area of intensive land use. |
| Chlorophyll-a | Green pigment found in plants; used to measure the amount of algae in the lake. |
| Conductivity | A measure of the electrolytes in the water, elevated by the presence of salts resulting from soil composition, faulty septic systems, or road salts. |
| Cultural Eutrophication | When human activities lead to the premature aging of a lake or pond. |
| Dimitic | A lake that mixes freely twice a year (once in the spring and once in the fall) and is thermally stratified in the summer and has stable temperature in the winter. |
| Dissolved Oxygen | Milligrams of oxygen per liter of water, produced by algae and larger plants, and mixed into the water from the air, used by fish, aquatic insects, crayfish and other aquatic animals (fish need more than 1 milligram per liter to survive). |
| Dredging | Removing solid matter from the bottom of a water body to make a deeper channel. |
| E. COLI | A common bacteria that is specific to the intestines of warm blooded animals; used as an indicator of the possible presence of other, more harmful (pathogenic) bacteria. |
| Ecology | The study of the interactions between organisms and their environments. |
| Epilimnion | The upper, well-circulated, warm layer of a thermally stratified lake. |
| Erosion | The process in which a material is worn away by a stream of liquid (water) or air, often due to the presence of abrasive particles in the stream. |
| Eutrophic | Nutrient rich waters, generally characterized by high levels of biological production. Lowest lake classification. |
| Eutrophication | Lake aging accelerated by increased nutrient input exceeding the natural supply. |
| Exotic Species | Plant or animal species introduced to an area from another country or state that is not native to that area. |
| Fertility | Capacity to sustain plant growth |
| Food Chain | The interdependency of producers, consumers, and decomposers. |
| Groundwater | (1) water that flows or seeps downward and saturates soil or rock, supplying springs and wells. The upper surface of the saturated zone is called the water table. (2) Water stored underground in rock crevices and in the pores of geologic materials that make up the Earth's crust. |
| Headwater | The source and upper reaches of a stream; also the upper reaches of a reservoir. |
| Hypolimnion | The deep, cold, relatively undisturbed bottom waters of a thermally stratified lake. |
| Internal Loading | Release of phosphorus from the lake's bottom sediments into the bottom layer of the water; enhanced by oxygen levels on the bottom of the lake which are less than 0.5 milligrams per liter. |
| Kemmerer Bottle | A piece of equipment used to collect water samples from a specific depth in a lake or pond. |
| Lake Aging | Natural process by which a lake fills in over time. |
| Leaching | The process by which soluble materials in the soil, such as salts, nutrients, pesticide chemicals or contaminants, are washed into a lower layer of soil or are dissolved and carried away by water. |
| Lentic | Referring to standing waters as in ponds and lakes. |
| Limiting Nutrient | An essential substance for plant growth, which is present in the environment in the least amount relative to the needs of the plant. |
| Limnology | The study of the biology, chemistry, and physics of freshwater lakes and ponds. |
| Littoral | The shoreline zone of a lake where sunlight penetrates to the bottom and is sufficient to support rooted plant growth. |
| Lotic | Referring to running waters as in streams and rivers. |
| Mesotrophic | Waters containing an intermediate level of nutrients and biological production. |
| Metalimnion | The middle layer of water in a thermally stratified lake, between the epilimnion and hypolimnion, where the decrease in temperature with depth is at its greatest. |
| Monomictic | Cold Lakes. Lakes with water temperatures never greater than 4oC and with only one period of circulation in the summer. These lakes are typically found in the Arctic or mountains and although they may be ice-free for brief periods in the summer, are in frequent contact with glaciers or permafrost. |
| Monomictic | Warm Lakes. Lakes with water temperatures that do not drop below 4oC and circulate freely in the winter. These lakes stratify directly in the summer. Warm monomictic lakes are common to warm regions of the temperate zones, in particular in areas influenced by ocean climates and in mountainous areas of subtropical latitudes. |
| Non-Point Pollution | Pollution originating from a diffuse area (not a single point) in the watershed, often entering the water body via surface runoff or groundwater. |
| Nutrients | Inorganic substances required by plants to manufacture food by photosynthesis. Phosphorus is the nutrient that usually limits the amount of aquatic plant growth in New Hampshire lakes. |
| Oligotrophic | Nutrient poor waters, generally characterized by low biological production. Highest lake classification. Oligo = "Little", Trophic = "Food" |
| Oxbow Lake | A crescent-shaped body of water formed as a meandering river gradually cuts through the outer bank at the beginning of a looping turn and joins directly with the channel downstream from the turn. |
| Paleolimnology | The science that studies the remains of plants and animals in such habitats as lakes, bogs, and marshes. |
| Periphyton | An assemblage of microorganisms (plants and animals) firmly attached to and growing upon solid surfaces, such as the bottom of a stream, rocks, logs, pilings, and other structures. |
| pH | Measure of how acidic the water is, on a scale of 1-14; 1 is very acidic, 14 is very basic. New Hampshire lakes tend to be acidic due to acid rain and snow. |
| Phosphorus | The nutrient most necessary for plant and algal growth in a New Hampshire lake; comes from many sources including faulty septic systems, lawn fertilizers, and decaying plant matter. |
| Phytoplankton | Microscopic plant life that float within or on top of lake water. |
| Plankton Net | Fine mesh net used to collect microscopic plants and animals. |
| Point Source Pollution | Pollution often resulting from discharges into water from identifiable sources (points), such as industrial waste or municipal sewers. |
| Polymictic | Term used to describe shallow lakes that mix more than twice a year. These lakes mix on a daily basis or every few days. |
| RipRap | Large rocks placed along the bank of a waterway to prevent erosion. |
| Runoff | Precipitation that enters surface waters from overland flow and from groundwater. |
| Secchi Disk | An instrument used for measuring transparency; for lakes, a 20-cm diameter disk with black and white quadrants. |
| Sedimentation | The transport and deposition of sediment particles by flowing water. |
| Silt Screen | A sheet of fabric placed like a fence around construction sites that trap sediment and prevents it from entering a water body. |
| Thermal Stratification | Process by which deeper lakes become layered in the summer months, with warmer water at the surface and colder water sinking to the bottom; because layers form chemical and biological barriers, limnologists sample at each layer of the lake. During the winter months, when ice forms on the lake, INVERSE THERMAL STRATIFICATION of water occurs under the ice, in which colder, less dense water overlies warmer, more dense water near the temperature of maximum density at 4 degrees Celsius. |
| Thermocline | The point of maximum temperature decrease with depth in a thermally stratified lake. |
| Transparency | A measure of the water's clarity; the depth at which a Secchi disk can be seen below the surface of the water; reduced by the presence of algae and suspended materials such as silt and pollen. |
| Tributary | Stream, inlet. |
| Trophic | Classification: Biologically ranking the quality of lakes using a model that incorporates several parameters. In New Hampshire these parameters are: chlorophyll-a, Secchi disk transparency, aquatic plant abundance, and dissolved oxygen. |
| Trophic State | The trophic state of a lake is a general concept with no precise definition and no well-defined units of measure. In general, trophic state refers to the biological production, both plant and animal life, that occurs in a lake. The level of production that occurs is defined by several factors, but primarily by the phosphorus supply to the lake and the volume and residence time of the water in the lake. (Refer to oligotrophic, mesotrophic, eutrophic) |
| Turbidity | The cloudiness of small particles, such as silt and clay, suspended in the water. |
| Vernal Pool | A contained basin lacking a permanent visual outlet. It may not contain water throughout the entire year and does not support fish. |
| Water Residence Time | The number of years required to completely replace the water volume of a lake by incoming water, assuming complete mixing. |
| Watershed Management | Implementing practices within a watershed designed to protect or restore the water quality of the receiving waterbody. Such practices may include the implementation of BEST MANAGEMENT PRACTICES. |
| Watershed | Land draining to a particular waterbody; often described as a funnel, where the lake is the bottom of the basin, collecting all the water that falls inside the funnel. |
| Zooplankton | Microscopic animal life that float within or on top of lake water. |
