Glossary of Common Terms

September 28, 2023

Algae: Large group of mainly water-living organisms that live by photosynthesizing, getting energy from sunlight. Neither plants nor animals, they range from single-celled organisms to multicellular forms like kelp.

Algal bloom: Rapid population growth of algae in water. This is often caused by pollution with excess nutrients. Algal blooms can deplete oxygen in water as well as release poisons harmful to fish, birds, and animals including humans.

Amplitude: For water waves it is the height (or depth) of the wave above the level of undisturbed water. The greater the amplitude of a wave, the more energy it carries and the more damage it will do to the shoreline.

Balanced Ecosystem: An Ecosystem where the mix of plants and animals remains stable over time.

Biodiversity: A measure of the varieties of species that inhabit an ecosystem. Basic biodiversity tends to be higher nearer the equator where more solar energy allows more species to be supported. Controllable environmental factors like pollution and invasive species can reduce biodiversity by harming the ecosystem.

Biological Oxygen Demand: One factor used to determine Water Quality. Quantity of oxygen used by aerobic bacteria to break down organic matter in the lake that typically comes from surface runoff. High demand depletes dissolved oxygen used by other species. High is bad.

Blue-green algae (Cyanobacteria): A type of bacteria (technically not algae) that gets energy from the sun, like plants. They can reproduce rapidly (bloom) in waters polluted with nitrogen wastes. They consume oxygen in the water causing fish and other organisms to die. Blooming cyanobacteria can also produce a variety of poisons directly fatal to birds and mammals.

Bog: A Wetland with wet, spongy, and poorly drained soil.

Cisco (Coregonus artedi) also Northern Cisco, Lake Herring, Tullibee: A once abundant salmon-family sport fish, Cisco are sensitive to predation by non-native fish species as well as environmental degradation and warming water. Since 2012, they have not been found in Clear Lake.

Clarity, Water (Transparency): A measure of how deep light penetrates into the lake. Specifically, it measures the haziness of water caused by large numbers of suspended particles both organic and inorganic. The deeper sunlight penetrates into water, the more it stimulates aquatic vegetation to release oxygen that supports a diverse ecosystem. Loss of transparency may be caused by suspended soil particles in runoff from agriculture, construction, or storm water. Loss of transparency is also caused by overgrowth of phytoplankton. (Note: Water with high clarity or transparency has low turbidity.)

Conservation Easement: A voluntary legal agreement between the landowner and the government or a land trust to permanently protect a property by limiting its use and management for conservation or other environmental purposes. While the landowner retains ownership, tax advantages, the right to sell, and other privileges, the preservation of the land will continue in perpetuity.

Cyanobacteria (Blue-green algae): A type of bacteria (technically not algae) that get energy from the sun, like plants. They can reproduce rapidly (bloom) in waters polluted with nitrogen wastes. They consume oxygen in the water causing fish and other organisms to die. Blooming cyanobacteria can also produce a variety of poisons directly fatal to birds and mammals including people.

Dissolved Oxygen: One of the more important factors used to determine Water Quality. It measures oxygen dissolved in the water as a proportion of the maximum at that temperature. Cold water naturally holds more than warm. Dissolved oxygen is essential for fish and other lake life. High is good.

Ecosystem: A complex system of plants and animals that share a common physical environment. A Balanced Ecosystem means the mix of plants and animals remains stable over time.

Eutrophic to Hypereutrophic (Trophic State Index 60–100): A measure of the amount of algal growth and other biological production in the lake. Highly eutrophic lakes have high levels of nutrients meaning the water quality is poor. Frequent algal blooms can reduce oxygen levels killing animal life and lowering biodiversity.

Eutrophication: The process where lake waters become murky from an overgrowth of algae and other microscopic organisms (the trophic state index becomes high). Eutrophic waters can support fewer large animals like birds and fish.

E. coli (Fecal Coliform) Bacteria: One factor used to determine Water Quality. Measured level of Escherichia coli bacteria present in water. Presence of the bacteria, found in the lower intestines of warm-blooded animals, indicates contamination of the water by fecal wastes. Some strains cause food poisoning and other diseases.

Fen: A grassy wetland area where water is flowing in the root zone of the plants.

Fetch: The distance wind travels over water. The longer the fetch, the more wind energy that is transmitted to the water raising wave height.

Filamentous Algae (Pond Scum): Overgrowth of non-harmful (but unpleasant) common algae that grows well in warm and sunny weather. It looks like green fur on the lake bottom. When it breaks free, the algae floats to the surface and collects in mats on the downwind shoreline where it decomposes and smells.

Habitat: The natural place for an organism to live and grow. Suitability of a habitat is determined by climate factors like seasonal variations in temperature, humidity, and availability of light as well as environmental factors such as soil richness, types of vegetation present, and availability of water. Also important is how the organism interacts with Native Plants and Native Animals within the habitat. Examples of habitats are savannas, forests, and prairies.

Hydraulic Retention Time (Retention Time): The time water spends within a given aquifer or lake system. Retention time can affect the amount of pollutants transferred into or out of the water as it passes through the system.

Hydrology: The study of water and how it moves through a given ecological system.

Hydrological Cycle (Water Cycle): Movement of water above, below, as well as on the surface of the Earth. Water cycles through various atmospheric, geological, and biological systems by a number of processes including evaporation and precipitation.

Invasive species: A new, non-native species which enters an ecosystem. If there are no natural predators, the population of an invasive species can explode threatening to crowd out other native species. A native species may also act as an invasive species if human activity removes a predator or otherwise unbalances the ecosystem. Invasive plant species in the Clear Lake watershed include starry stonewort, Eurasian watermilfoil, curly leaf pondweed, coontail, and garlic mustard.

Lake: According to the state of Indiana, a freshwater lake is a body of standing water with natural water that contains not more than 10,000 milligrams per liter of total dissolved solids (i.e. it is not salt water).

Land Conservancy (Land Trust): Private, non-profit organization with a mission to acquire land and conservation easements so the land can be protected and conserved for its natural, historic, scenic, or recreational value.

Land Management (Stewardship): Preserving land and water quality by various techniques. These include:

Forest health improvement — Actions designed to produce fewer but higher quality trees.
Selective tree harvest — Removing poor quality trees improves growth of quality trees and increases habitat diversity.
Prescribed burns — Low intensity fires remove underbrush and leaf litter encouraging growth of existing trees.
Mowing — Another way to control weed growth, limit woody plant intrusion into grasslands, or prepare for a prescribed burn.
Invasive species control — Removal of undesirable, non-native species that compete with native species.
Herbicides — Chemicals toxic to plants used in limited applications when no other reasonable means of control will work.

Light Pollution: Excess artificial light during the night disrupts many elements in the natural environment. These disruptions can be detrimental not only to the health of the ecosystem but to human health as well.

Marsh: A wetland area where grasses make up most of the plant life.

Mesotrophic (Trophic State Index 40–60): A measure of the amount of algal growth and other biological production in the lake. A Mesotrophic lake has medium levels of nutrients in the water. Mesotrophic lakes and ponds commonly have clear water with submerged aquatic vegetation.

Native Animal: An animal is native to an ecosystem if it occurs there naturally without human introduction and/or migration due to climate change.

Native Plants: A plant is native if it occurs naturally in an ecosystem without either human introduction or migration due to climate change.

Nitrogen: One factor used to determine Water Quality. Small amounts of nitrogen compounds in water are necessary for life, but excess pollution with nitrates and nitrites from sewage, decomposing organic waste, as well as agricultural and lawn fertilizer runoff will cause eutrophication. Low levels are good.

Nutrient Loading and/or Sediment Loading: Run off water into streams and lakes contains various levels of nutrients and eroded soil particles that can affect water quality depending on their types and concentrations.

Nutrient pollution: In water, overabundance of nutrients like phosphates or nitrogen compounds stimulates growth of phytoplankton and algae that lowers water clarity and quality leading to eutrophication.

Oligotrophic (Trophic State Index 0–40): A measure of the amount of algal growth and other biological production in the lake. An oligotrophic lake has low levels of nutrients in the water and is very clear. However, lack of abundant plant life can limit dissolved oxygen and the number of fish species supported.

pH: One factor used to determine Water Quality. Measure of acidity to basicity of water on a scale of 0 (strong acid) to 14 (strongly basic). Aquatic ecosystems do best at a pH between 6.5 and 8.2. Medium is good.

Phosphate (Phosphorus) Level: One factor used to determine Water Quality. Small amounts of phosphates (compounds containing the element phosphorus) in water are necessary for marine life, but excess phosphate pollution from sewage, agricultural, and lawn fertilizer runoff will cause eutrophication. Low is good.

Photosynthesis: The light-powered process used by green plants and other organisms to make food out of carbon dioxide and water.

Phytoplankton: Plankton composed of microscopic plants.

Plankton: Diverse collection of tiny organisms found living in water but unable to propel themselves. Types include bacteria, archaea, algae, and protozoa. Some species can be used as food by fish and other species, but other types are harmful.

Pollination: Transfer of pollen grains from the male (anther) part of the flower to the female (stigma) part. The act of pollination fertilizes the plant which can then produce seeds to grow the next generation of plants.

Pollinator Garden: A pollinator garden patch contains flowers and other types of plants that attract pollinators. This provides food for the pollinators as well as ensures pollination of other plants in the surrounding area.

Pollinators: Organisms that physically pollinate plants. Honeybees are familiar pollinators, but birds, bats, moths, butterflies, and many other insects and mammals also pollinate plants. Many plants depend on pollinators to reproduce. In return many pollinators depend on plants and/or plant pollen for their food supply.

Pond Scum (Filamentous Algae): Overgrowth of non-harmful (but unpleasant) common algae that grows well in warm and sunny weather. It looks like green fur on the lake bottom. When it breaks free, the algae floats to the surface and collects in mats on the downwind shoreline where it decomposes and smells.

Prairie: Large open grassland.

Predictive Modeling: Using statistics to predict outcomes. Changes in climate, land use, agricultural processes, and many other factors affect the natural environment. Existing statistical measurements can be used to forecast future outcomes allowing better land management decisions to be made.

Prescribed Burn (Prescribed Fire): Some ecosystems have adapted to periodic wildfires and actually require them to maintain their biodiversity. When wildfires are suppressed, a controlled, prescribed burn is used to insure sustainability of the ecosystem.

Retention Time (Hydraulic Retention Time): The time water spends within a given aquifer or lake system. Retention time affects both the amount of pollutants transferred into and out of the water as it passes through the system.

Savanna: Grassy area with few trees.

Scour: Eroded holes in the lake bed caused by wave action. This often occurs near sea walls.

Sea Wall: A constructed barrier, often concrete, metal, or wood, erected to protect a shoreline from immediate erosion. Sea walls do not dissipate the energy of wave action but reflect it back into the water. Erosion increases in front of and to the sides of a sea wall. Erosion problems are deflected, not solved. (See Shore Line)

Secchi Disk: Tool used to measure water transparency (turbidity). In freshwater lakes it is a 20 cm (8 in) disk divided into black and white, pie-sliced quarters. To measure transparency, the disc is mounted on a long pole and lowered into the water until it can no longer be seen. The depth at which the disk disappears is called the Secchi Depth, a measure of transparency.

Sediment Loading and/or Nutrient Loading: Runoff water into streams and lakes contains various levels of nutrients and eroded soil particles that can affect water quality depending on their types and concentrations.

Shore Line: The type of boundary between lake waters and the land changes the interaction of both wind driven and activity driven waves. This can affect the overall health of the lake. As wave driven erosion eats away the shoreline, it also decreases water clarity. Typical types of shorelines are:

Natural Shoreline: Sand and soil with native grasses, trees, and other plants helping keep soil in place. Steep natural shorelines will be eroded by wave action.
Concrete, Metal, or Wood Sea Walls: Although constructed sea walls protect a shoreline from immediate erosion, sea walls do not dissipate the energy of wave action but reflect it back into the water. Erosion increases in front of and to the sides of a sea wall. Erosion problems are deflected, not solved.
Glacial Stone (Field Stone) Shoreline: A gradually sloping shoreline covered with layers of rounded stones. The stones dissipate wave energy reducing erosion and improving water clarity.

Subwatershed: A smaller section of a larger watershed. Clear Lake has four subwatersheds that flow into it, the Cyrus Brouse, Harry Teeters, Peter Smith, and Alvin Patterson ditches. The Clear Lake watershed is itself a subwatershed of the Lake Erie watershed.

Suspended Sediment Level: Measurement of the fine particles of eroded soil and other debris carried by moving water. In a lake water flow slows down, and the largest particles settle out first with the smallest particles lingering.

Sustainability: The long-term viability and success of an ecosystem. The Clear Lake Township Land Conservancy promotes policies and actions designed to allow Clear Lake to be used and enjoyed by future generations.

Swamp: A wetland area dominated by trees.

Transparency (Water Clarity): A measure of how deep light penetrates into the lake. Specifically, it measures the haziness of water caused by large numbers of suspended particles both organic and inorganic. The deeper sunlight penetrates into water, the more it stimulates aquatic vegetation to release oxygen that supports a diverse ecosystem. Loss of transparency may be caused by suspended soil particles in runoff from agriculture, construction, or storm water. Loss of transparency is also caused by overgrowth of phytoplankton. (Note: Water with high clarity or transparency has low turbidity.)

Trophic Index (Trophic State Index or TSI): The measure of the amount of algal growth and other biological production in the lake. A measure of the amount of eutrophication. High rates of biological production (eutrophication) mean algae and other scummy organisms are taking over the ecosystem. Lower rates mean better water quality.

Oligotrophic (TSI 0–40): Low levels of nutrients in the lake mean water is very clear. However, lack of abundant plant life can limit dissolved oxygen and the number of fish species supported.
Mesotrophic (TSI 40–60): Medium levels of nutrients in the water. Mesotrophic lakes and ponds commonly have clear water with submerged aquatic vegetation.
Eutrophic to Hypereutrophic (TSI 60–100): High levels of nutrients mean poor water quality. Frequent algal blooms can reduce oxygen levels killing animal life and lowering biodiversity.

Trophic Level: The food position of an organism ranked by its eat-or-be-eaten status. Specifically, it is the number of steps the organism is from the bottom of the food chain.

Plants absorb nutrients from the environment. The bottom of the food chain.
Herbivores eat plants.
Carnivores eat herbivores and plants.
Apex predators eat other carnivores and lower trophic levels.
Keystone predators can control an entire food web by eating all trophic levels.

Turbidity: One factor used to determine Water Quality. A measure of the degree that suspended solids like silt and plants such as algae cloud the water and decrease its clarity. Note: turbidity is inversely related to water transparency. High turbidity means low clarity and vice versa. Low turbidity is good.

Wake: Turbulence created by a craft moving through water. The greater the height of the waves created in the wake, the more energy the waves will carry and the more damage they can do to other watercraft or the shoreline of the lake.

Water Clarity (Transparency): A measure of how deep light penetrates into the lake. Specifically, it measures the haziness of water caused by large numbers of suspended particles both organic and inorganic. The deeper sunlight penetrates into water, the more it stimulates aquatic vegetation to release oxygen that supports a diverse ecosystem. Loss of transparency may be caused by suspended soil particles in runoff from agriculture, construction, or storm water. Loss of transparency is also caused by overgrowth of phytoplankton. (Note: Water with high clarity or transparency has low turbidity.)

Water Cycle (Hydrological Cycle): Movement of water above, below, as well as on the surface of the Earth. Water cycles through various atmospheric, geological, and biological systems by a number of processes including evaporation and precipitation.

Water Quality: Measurements of various interacting factors determine environmental water quality. Good water quality means a lake is fishable, swimmable, and recreational. While there are many ways to test water quality, the Conservancy considers the following to be key factors:

Dissolved Oxygen – One of the more important factors used to determine water quality. It measures oxygen dissolved in the water as a proportion of the maximum at that temperature. Cold water naturally holds more than warm. Dissolved oxygen is essential for fish and other lake life. High is good.
Biological Oxygen Demand – Quantity of oxygen used by aerobic bacteria to break down organic matter in the lake that typically comes from surface runoff. High demand depletes dissolved oxygen used by other species. High is bad.
E. Coli – Bacteria contaminant common in fecal waste from animals that can be a health risk for humans and animals. The lower, the better.
pH – Measure of acidity to basicity of the water on a scale of 0 (strong acid) to 14 (strongly basic). Aquatic ecosystems do best at a pH between 6.5 and 8.2. Medium is good.
Water Temperature — Lower temperature lake waters hold more dissolved oxygen which supports fish and a diverse range of other macro invertebrates. Shallow waters warm more quickly while deeper waters remain cool. Low is good.
Phosphate (Phosphorus) Level — Small amounts are necessary for life, but excess phosphate pollution from sewage, agricultural, and lawn fertilizer runoff will cause eutrophication. Low is good.
Nitrogen — Small amounts are necessary for life, but excess pollution with nitrates and nitrites from sewage, decomposing organic waste, as well as agricultural and lawn fertilizer runoff will cause eutrophication. Low levels are good.
Turbidity — The degree that suspended solids like silt and plants like algae cloud the water and decrease clarity. Lake turbidity can be caused by soil erosion in runoff from construction, agriculture, and other processes that expose soil to precipitation. In a lake suspended solids can also be generated by activity that causes shoreline erosion and lake bottom disturbance. Turbidity also is caused by blooms of algae. Low is good.

Water Temperature: One factor used to determine Water Quality. Lower temperature lake waters hold more dissolved oxygen which supports fish and a diverse range of other macroinvertebrates. Shallow waters warm more quickly while deeper waters remain cool. Low is good.

Watershed: A geographical area in which any precipitation flows to a common point, often into a body of water. As water flows through the land, the soil and vegetation within the watershed play a role in adding or removing nutrients and contaminants in the water.

Subwatershed: A smaller section of a larger watershed. Clear Lake has four subwatersheds that flow into it: the Cyrus Brouse, Harry Teeters, Peter Smith, and Alvin Patterson ditches. The Clear Lake watershed is a subwatershed of the Lake Erie watershed.

Wetland: An ecosystem that floods and usually is water-saturated.

Swamp: A wetland area dominated by trees.
Marsh: A wetland area where grasses make up most of the plant life.
Fen: A grassy wetland area where water is flowing in the root zone of the plants.
Bog: A wetland with wet, spongy, and poorly drained soil.