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FAQs and Glossary

Water quality science can be complex, and the associated terminology can be confusing for those readers not involved in the day-to-day business of water management. However, many people with non-technical backgrounds are interested in the condition of our lakes and rivers. This site has been designed to provide quick answers to common questions.

We have provided responses to three categories of questions and concerns, followed by a general glossary to explain the meaning of technical terms. Also included are some links to other sources of detailed information.

If you have questions or require further information, please contact us at:

Common Questions about Lakes

How can I find out about the water quality of my lake?

Alberta Environment and Parks (AEP) monitors the water quality of lakes and reservoirs across the province. Due to the large number of water bodies, the department is unable to check every lake every year. Surface water monitoring and more intensive studies are also conducted with volunteer groups, industries and researchers. All water quality data are verified and stored in a central Water Database System and may be obtained by contacting:

Data or summary data reports on common water quality parameters, including water clarity, conductivity, pH, alkalinity, nutrients and ion chemistry are available on the Surface Water Quality Data web page. You can also access an inventory of sampling locations as well as trophic status charts for chlorophyll-a (a measure of the amount of algae) and total phosphorus (the key plant nutrient) for Alberta lakes.

If you have more specific needs or concerns, please contact:

For information regarding public beach monitoring and advisories, visit Alberta Health Services:

What are algae?

Algae are a diverse group of aquatic plants that form an important component of aquatic food chains. Many species float or are suspended in water (called phytoplankton), while others grow attached to submerged substrates, including rocks, plants, sediment and animals. Algae range extensively in size and shape, from microscopic, single-celled organisms to colonial species that resemble larger plants. Most algae obtain their nutritional needs directly from the water itself. Primary nutrients include nitrogen, phosphorus and carbon. Algae serve as a vital food source for microscopic animals, which then provide food for fish and other aquatic life.

What are cyanobacteria?

Cyanobacteria is a modern term used to describe a group of bacteria that, in the same manner as algae and plants, convert sunlight and nutrients into energy required for growth and reproduction. Because they share many similarities in overall appearance, nutrient requirements and habitat with algae, cyanobacteria were historically classified as algae and are still commonly referred to as blue-green algae.

More than 100 species of cyanobacteria have been recorded in Alberta. Like algae, some species of cyanobacteria are suspended in water, while others grow attached to submerged substrates. Some are microscopic, single-celled organisms and others form large colonies easily seen in the water. Although they coexist with algae, cyanobacteria possess adaptations, such as the ability to use atmospheric nitrogen for growth, that often allow them to overtake algae populations. This gives cyanobacteria a competitive advantage in nitrogen-poor lakes. Most species also have the ability to regulate buoyancy, in order to position themselves at depths with optimum sunlight for growth. As a result, cyanobacteria grow extremely well during the warm summer months in Alberta's nutrient-rich lakes.

Cyanobacteria may impart noxious odour or disagreeable tastes to water and fish. Decomposition of cyanobacteria blooms may also lead to excessive depletion of dissolved oxygen in waterbodies, which in turn can cause winter and summer fish kills. More troublesome is the fact that several common species are known to produce potent liver and/or nerve toxins. These toxins have been linked to deaths of livestock, pets and wildlife, as well as mild to severe illness in humans consuming contaminated water.

Why does my lake turn green?

Phosphorus and nitrogen are important nutrients for the growth of algae and cyanobacteria. For most lakes, these nutrients enter primarily from the surrounding watershed. However, nutrient-rich sedimentary bedrock and soils also exist throughout much of Alberta, which can cause naturally elevated concentrations of dissolved phosphorus and nitrogen in lakes. Once in a lake, nutrients can remain for some time and may cycle annually or more often. For instance, phosphorus is released from the bottom sediments of lakes into overlying water during periods of oxygen depletion. This deep, phosphorus-enriched water can mix with shallow surface waters during windy periods or during spring and fall turnover, in effect fertilizing the lake. The results are often excessive growth of both cyanobacteria and algae, which can make the lake look green and murky. When weather conditions are right, cyanobacteria may accumulate at the water's surface in what is known as a cyanobacterial (blue-green algal) bloom. Though this problem is natural to some extent, activities in and around lakes that further increase nutrient loading (including cottage and residential development, agriculture, forestry and other industry), can exacerbate it.

For further information on cyanobacterial blooms, refer to:

What are macrophytes?

This is a general term for large aquatic plants. Often referred to as "weeds," these plants are common in Alberta's shallow, productive lakes, and they represent a key component in lake ecosystems. Most are rooted plants that obtain their nutrients from sediments in the lake or river bottom. Some, such as cattails, emerge from the water, while others, such as pondweeds, are often referred to as submerged vegetation because they live under the water. A few types, like water lilies and duckweed, float on the surface.

Why are macrophytes considered important?

Macrophytes are essential to the ecological structure and function of lakes. For example, they provide food, oxygen and habitat for a wide variety of aquatic life, including fish. Other aquatic and terrestrial life, such as muskrat, amphibians, moose, waterfowl and other bird groups, rely on macrophytes for food, shelter and other habitat needs. Macrophytes also help to stabilize shorelines and lake bottoms, reduce erosion by suppressing wave action, and may help to maintain good water quality by taking up nutrients which would otherwise encourage algal growth.

Can I cut the weeds in front of my cottage?

Aquatic plants are an important part of a natural aquatic ecosystem. They provide habitat for fish and help maintain water quality by stabilizing sediment. Provincial and federal laws require an approval permit be obtained to remove aquatic vegetation.

More information, as well as application forms, can be found at:

Why do we get "itchy" after swimming in our lake?

Unfortunately, swimmer's itch is a common problem in many Alberta lakes, particularly in those with extensive weed beds and large waterfowl populations. The "itch" is caused by the intermediate stage of a parasite that normally requires ducks and aquatic snails as hosts. Humans come in contact with the tiny worm-like parasites, called schistosomes, while swimming. Although the parasites die, they cause an allergic reaction in the skin including itching. Be sure to shower well and towel down vigorously after swimming if you suspect your lake has these organisms.

Is it safe to eat the fish from my lake?

Limited data are available to define contaminant levels in fish tissues in Alberta lakes. Not all lakes have been tested. Lakes with fish and contaminant levels that are not safe for consumption are listed in the annual guide:

What causes the water level in my lake to rise and fall?

Spring runoff and early summer rains usually produce the greatest volumes of inflow in Alberta, while lowest runoff occurs in fall. Lake levels tend to reflect these patterns, but their responses can be moderated by long-term climatic factors as well as by dams or weirs on the outflow. Groundwater inflows and outflows can also be important factors in regulating lake levels but are difficult to measure. The activities of beavers can play a surprisingly influential role in controlling lake inflows and outflows.

More information on lake levels can be found at:

How can I protect my lake?

Alberta lakes are under pressure from increased development of industry, agriculture, residential, and recreational use. In addition to increased development, changing environmental factors have resulted in water quality, lake levels and ecosystem impacts. These cumulative effects surrounding lakes are creating various pressures on the lake that may not be sustainable.

Respect our Lakes is an education and awareness program that promotes shared stewardship and informs the public about lake and lakeshore values which aids in achieving lake management outcomes.

Common Questions about Rivers

How can I find out about the water quality of a river?

As with lakes, AEP regularly tests river water quality on a number of rivers and streams across the province. All collected data are archived into a comprehensive water database. The department also partners with industries, municipalities and stewardship groups on many studies and projects. If you would like to obtain basic water quality data for a specific river or stream, visit the water quality reports web page at:

For more detailed data contact:

If you have concerns or questions about a river or stream, contact us at:

Where can I get river flow data?

The measurement of water in Alberta is accomplished through the operation of a variety of water data collection networks: hydrometric, snow survey, meteorological, telemetry, groundwater and water quality.

For more information on river flow data see:

Is the water quality in the river safe for swimming?

This is a difficult question to answer with certainty. Although Alberta is making good progress in treating industrial and municipal wastes, particularly in large urban areas, there will always be some degree of uncertainty caused by the potential presence of untreated wastes (for example, storm sewer outflows) or other sources, such as livestock/wildlife feces. In pristine areas the risk is likely less, and this pattern tends to be borne out by the results of water quality testing. However, no agency has complete or continuous information on all rivers so individuals must assume all risk for decisions made.

Is it safe to drink water from the river?

It is has long been advised that you do not drink untreated surface water anywhere in Alberta (or elsewhere in Canada). Although many waters may appear pristine, they may still contain natural chemicals or organisms that could make you ill. Check with Alberta Health Services – Environmental Health Program to find out the best methods for dealing with your drinking water needs. Municipal water treatment plants evaluate treated river water against Canadian Drinking Water Guidelines to determine whether the water is safe to drink.

Is it safe to canoe on the river?

Canoeing on the river can be limited by a number of factors, including high flows, low flows, current, severe weather events and time of year. For further information on flow advisories see:

For detailed information on the presence of rapids, travel times, access points, etc., contact your local canoe or kayak club.

Is it safe to snowmobile or ski on frozen rivers during winter?

River currents are continuously changing under ice as winter progresses, and as various sections freeze and thaw. The thickness of river ice is therefore highly unpredictable. We recommend that you avoid this dangerous environment as much as possible.

Are "real time" water quality data available?

The term "real time" refers to information collected in the field and transmitted almost instantly through the use of advanced electronic instrumentation coupled with satellite communications technology. Each year a certain number of river locations in Alberta are monitored using this approach. However, the technology is only developed to allow a few basic characteristics to be measured. The primary characteristics reported are: temperature, dissolved oxygen, pH and conductivity.

For real time data available on the Highwood River (during summer) and on the Athabasca River (during winter), see:

Is it safe to eat fish from the river?

As with lakes, limited data are available to define contaminant levels in river fish tissue. Check the annual Alberta Guide to Sport Fishing Regulations for a listing of consumption advisories.

Problems and Issues

Are cyanobacterial blooms toxic?

Alberta's nutrient-rich lakes support an abundance of cyanobacteria, which can make the lake appear green and murky. When weather conditions are right, cyanobacteria may congregate at the water's surface in what is known as a cyanobacterial bloom. Bloom-forming species of cyanobacteria produce many compounds, some of which have toxic properties.

In Alberta's lakes, the most common are the liver toxins called microcystins. Microcystins have been responsible for illness and death of livestock, pets, and wildlife following the consumption of cyanobacteria-infested water. Microcystins have also been linked to incidences of gastrointestinal illness in humans.

Less common are the neurotoxins (nerve toxins), including anatoxin-a, anatoxin-a(s), and saxitoxin. Although neurotoxic blooms tend to be more potent than those containing only microcystin, they occur less frequently. Neurotoxins have been linked to sporadic die-offs of ducks, shorebirds, and bats, as well as pets and livestock.

Lastly, some cyanobacteria also produce dermal toxins that can yield dermatitis symptoms similar to swimmer’s itch and may include skin irritation, rashes, redness of the eyes, swollen lips, sore throat and hay fever-like allergic reactions. Incidences or outbreaks of contact dermatitis through recreational activities such as swimming, water skiing and boating have been reported.

It is important to realize that blooms usually comprise several coexisting species of cyanobacteria in varying abundance. This means that the majority of blooms will contain some amount of toxin. This also means that more than one toxin can be present at any given time. Although there are no recorded human fatalities linked to toxic cyanobacterial blooms in Alberta, these have occurred elsewhere around the world. Hence, all blooms should be treated with caution. Never consume untreated surface water at any time and provide alternative drinking water for pets and livestock during blooms and for up to two weeks after the blooms' disappearance. Contact with blooms should also be avoided.

For further information on cyanobacterial blooms and toxicity, see:

For health concerns and questions about whether to swim in a lake, please visit Alberta Health Services:

What can I do to control the algae in my lake/dugout?

The best way is to control the amount of nitrogen and phosphorus (found in sewage, grey water, animal feces, fertilizers or silt from land erosion) that enters the water body. Provide a vegetative buffer of trees, shrubs and grasses around the water body. This will prevent erosion by holding soil and stabilizing the shoreline. A well-maintained vegetative zone may also filter out sediments, pesticides, microbes and heavy metals carried by rain and snowmelt runoff.

Why does foam form on lakes, rivers, and streams?

Plants, algae and cyanobacteria inhabiting watersheds and surface waters produce many organic compounds. Some of these compounds are surface-active agents or surfactants, as they are commonly called. Like soap, surfactants lessen the surface tension of water. Diminished surface tension allows air bubbles to persist at the water's surface. Vigorous mixing of surface water by waves, water currents, rapids and boating activity generates bubbles that persist and build up as foam.

In lakes, reservoirs and ponds, foam collects along windward shores or may form long, evenly spaced lines, called "windrows," in open water. In rivers and streams, foam is often found downstream of rapids, in back-currents (eddies), or below waterfalls and dams. While mostly natural, foam can be caused by synthetically produced surfactants released to surface waters. Natural foam typically appears off-white to brown in colour and smells like fish or earth, whereas foam resulting from pollution such as detergent, is white in colour and may have a fragrant, perfume-like smell.

For more information, see:

What causes fish kills?

Sometimes fish are killed by accidental spills of toxic materials. In Alberta, however, fish kills most commonly result from low dissolved oxygen levels or heat stress. Under certain conditions, cyanobacterial blooms in lakes can "collapse" and start to decompose rapidly. This decay can result in low dissolved oxygen levels. Researchers have also identified ammonia, released during cyanobacterial decomposition, as a cause of summer kill.

What is Beaver Fever?

Beaver Fever, or giardiasis, is an intestinal disorder characterized by nausea, diarrhea and fatigue. Beaver Fever is caused by Giardia, a microscopic intestinal parasite that can infect many mammals, including humans. It can be transmitted through water contaminated by fecal material.

What is Cryptosporidium?

Cryptosporidium is also an intestinal parasite, which can infect warm-blooded animals, including livestock, wildlife and humans. It can be transmitted through water contaminated by feces. Crpytosporidium causes severe diarrhea, which can be fatal to immuno-compromised persons (e.g., those infected with AIDS, elderly). Neither Cryptosporidium nor Giardia can reproduce outside of their host animal.

For further information, see:

Is my well water safe?

Albertans who obtain their drinking water from alternate sources - such as private wells, dugouts, canals, streams and lakes - are responsible for ensuring that their own drinking water is safe. Have the water tested on a regular basis and apply the appropriate treatment options based on the water quality reports. AEP’s Working Well program works to ensure safe and secure groundwater supplies for water well users in Alberta.

Where can I get more information on groundwater?

In Alberta, groundwater is an essential resource - many rural residents rely on this resource for all of their domestic needs. Groundwater is also used for livestock watering, irrigation, and industrial processing, heating and cooling.

To find out more, see:

How can I arrange to get surface water tested for quality?

There are a number of analytical laboratories that perform water quality analysis. Depending on which chemical variables (e.g., nutrients, metals, bacteria, pesticides) you want to test your water for, the laboratory will charge you a fee to analyze the sample. They will also provide you with some basic guidelines on how to collect the sample and avoid contamination from other sources (e.g., dirty collection container or sediment in the water sample) which can compromise the results.

If you are concerned about your drinking water from your tap or groundwater well, contact:

Why does my tap water smell in the spring?

Spring runoff moves many substances from the land into streams and rivers. Some of the natural substances, as well as those from human activity, may have unpleasant tastes and odours. Municipal water treatment plants cannot always remove these tastes and odours, especially when the water is turbid and silty. However, the water is safe to drink.

Why should we protect the riparian zone?

The riparian zone is a margin of vegetation, which includes trees, shrubs and grasses from the waterline of rivers and streams. The vegetation plays a critical and complex role in filtering and slowing runoff from farmland, capturing sediments during flooding, and building the storage capacity for groundwater that maintains stream flow in dry periods, and through the fall and winter. It provides shelter and forage area for a wide variety of waterfowl and mammals.

What can be done to minimize livestock damage along rivers and streams?

Direct access to the water's edge by livestock can damage or destroy the vegetative zone. Stream banks and shorelines become trampled, destroying vegetation and exposing bare soil to wind and water erosion. In addition, fecal material is introduced directly into the lake or river, increasing health risks to recreational users.

For further information related to the protection of water quality and best management initiatives by agriculture visit:



Chemical: Water quality is assessed by measuring a variety of chemical substances (as well as biological and physical characteristics). All matter is composed of chemicals - even water (the familiar H2O). Most of the chemicals in water such as calcium, sodium and bicarbonate are natural.

Combined Sewers: Combined sewers are older drainage systems that carry both sanitary waste and stormwater runoff. During heavy rain, the capacity of the combined sewer to carry wastewater to the sewage treatment plant may be exceeded, and a discharge of the untreated waste to the river may occur. In Alberta, plans are underway to improve these older systems.

Concentration: Amount of a substance in a given volume of water. For the most common chemical substances, the concentration is expressed as milligrams per litre (mg/L: parts per million) or micrograms per litre (µg/L: parts per billion). However, the technology exists to measure substances at the part per trillion or quadrillion level.

Drainage Basin: Total area of land that contributes water and materials to a lake or river, either through streams or by localized overland runoff along shorelines.

Effluent Plume: When a discharge into the river has different water chemistry than that of the river, the discharge maintains its integrity for some distance downstream before it mixes completely with the river water. Such a plume is detectable by sampling across the river.

Non-Point Source Pollution: Pollutants that enter the river from diffuse or undefined sources, and usually carried by runoff. These sources include cleared or agricultural land, coal mines, construction sites, roads and urban areas. Air-borne non-point source pollutants can be deposited directly into a water body. Because non-point sources are diffuse, they are often difficult to identify or locate precisely, and thus pollutants from them cannot be controlled easily.

Point-Source Pollution: Pollutants entering the river from one, easily recognizable location such as a pipe associated with an industrial or municipal wastewater treatment facility.

Pollution: Contribution of substances from human activities that may adversely affect a desired use of water.

Runoff: Water that moves over or through soils on the land during snowmelt or rainstorms.

Watershed: A term often used interchangeably with the word "drainage basin", but in the strictest sense it refers to the outer boundary of the drainage basin itself, as defined by topographic features.


Specific Conductance: Or conductivity, indicates water's ability to conduct an electrical current. It provides an indication of the amount of dissolved substances in the water - when conductivity is high, the concentration of dissolved material is also high.

Suspended Solids: Particles suspended in the water, primarily soil particles eroded from the land. Suspended solids concentrations normally increase with increases in river flow, as a result of scouring of the river bed and banks. High suspended solids loads can cause siltation of the river bed and smother plants and animals, decrease light penetration, cause stress to aquatic organisms and reduce photosynthesis. In addition, suspended solids may adsorb organic compounds, heavy metals and nutrients.

Turbidity: Or cloudiness, of the water is determined by the presence of suspended particles such as clay, silt, organic matter and living organisms. High turbidity may reduce light transmission, and therefore reduce photosynthesis of aquatic plants.

Water Temperature: The temperature of the water plays an important role in influencing physical, chemical and biological processes, and is regulated mainly by the season, weather conditions, time of day and in moving water, the flow rate.

General Chemistry

Alkalinity: The acid-neutralizing capacity of water.

Biochemical Oxygen Demand (BOD): A measure of the amount of oxygen needed for microorganisms to convert organic matter to inorganic matter. It is typically measured as the amount of oxygen consumed in laboratory tests over a five-day period at 20 degrees Celsius.

Cyanide: A general term for a diverse group of organic and inorganic compounds containing carbon and nitrogen, some of which are toxic. They are generally found in low concentrations in surface waters as a result of natural decomposition of certain plants and metabolism of microorganisms. They are also released into the aquatic environment in discharges from mining industries, steel mills, oil refineries and electroplating industries.

Dissolved Oxygen: Required by aquatic organisms for aerobic respiration. Oxygen is added to the water by photosynthetic activity of plants and re-aeration from the atmosphere. It is removed from the water by respiration of bacteria, plants and animals and various chemical processes. In winter, ice cover restricts the amount of oxygen that can enter the water, and replenishment by photosynthesis is greatly reduced. In summer, dissolved oxygen levels may fluctuate dramatically from day to night.

Fluoride: Present in trace amounts in soil and rocks and is released naturally to the aquatic environment by geochemical weathering. Fluoride is also released into surface waters from municipal wastewater as a result of fluoridation of drinking water.

Hardness: A measure of the amount of certain dissolved substances in the water, primarily calcium and magnesium. Concerns with hardness relate mainly to encrustation and excessive soap consumption in water supplies, although it can also influence the form and toxicity of numerous heavy metals.

Major Ions: Occur naturally in water as a result of geochemical weathering of rocks, surface runoff and atmospheric deposition. The eight major ions - calcium, magnesium, sodium, potassium, bicarbonate, carbonate, sulphate and chloride - account for most of the total dissolved solids in surface waters.

pH: A measure of the intensity of the acid or base chemistry of the water. A pH of 7 is neutral, below 7 is acidic and above 7 is basic. Technically, pH is defined as the negative logarithm of hydrogen ion activity. pH in surface water is regulated by the geology and geochemistry of the area, and affected by biological activity. The distribution of aquatic organisms and the toxicity of some common pollutants are strongly affected by pH.

Total Dissolved Solids (TDS): A measure of the concentration of dissolved matter in water. It is measured by evaporating water that has passed through a very fine textured filter to remove suspended solids. The residue is then weighed. TDS is often used as an estimate of water's salinity, which may affect the distribution of aquatic organisms.

Metals and Trace Elements

Aluminum: Abundant in rocks and clays, and can be mobilized from soils by natural weathering. Sources also include effluents from industries that use aluminum in their processing or use alum as a flocculent. Low concentrations are not a concern, but toxicity of aluminum increases if the pH of the water is less than 6.

Arsenic: Released naturally into the aquatic environment as a result of weathering of arsenic-containing rocks, from industrial and municipal discharges, and from combustion of fossil fuels.

Barium: A common element in the earth's crust, although only trace levels are normally found in natural surface waters.

Boron: Released naturally into the aquatic environment from weathering of rocks and soil, and is present in municipal sewage.

Cadmium: Present in trace concentrations in fresh water as a result of natural weathering processes. Concentrations above about 0.01 mg/L can usually be attributed to human activities such as mining, agriculture and the burning of fossil fuels. Concentrations above this level may be toxic to aquatic life.

Chromium: Released into rivers by weathering of rocks and soil, and in industrial discharges such as from metal plating plants. Chromium is toxic to certain aquatic invertebrates at low concentrations, but fish are less sensitive.

Cobalt: Released into the environment from weathering of cobalt-rich ores and from anthropogenic sources such as emission from coal burning industries.

Copper: Sources to aquatic environments include the weathering of copper minerals and native copper, and numerous sources from human activities. Background concentrations in surface waters are usually below 0.02 mg/L. Higher levels are generally related to human activities.

Iron: Released naturally into the aquatic environment by weathering of sulphide ores and rocks and leaching from sandstones. Human sources include the burning of coal, acid mine drainage, mineral processing, sewage and landfill leachates.

Lead: Toxic to fish and other organisms, particularly in soft water. Although there are natural sources of lead, human sources often supply a greater quantity to surface waters. Sources include weathering of sulphide ores, urban runoff, atmospheric deposition and industrial and municipal discharges.

Manganese: An essential trace element for living things. Soils, sediments and rocks are significant natural sources of manganese, whereas industrial discharges are the primary source from human activities.

Mercury: Deposits occur in all types of rocks, and human sources of mercury to the aquatic environment include industrial and municipal discharges, atmospheric deposition or industrial emissions and leaching from landfill sites. Mercury is of particular concern because of its toxicity to aquatic organisms and its adverse effects on human health.

Nickel: Enters the aquatic environment through the weathering of rocks and as a result of human activities, primarily the burning of fossil fuels and from smelting and electroplating industries.

Selenium: Enters surface waters as a result of weathering and erosion of soils and discharge from copper and lead refineries and municipal wastewater.

Vanadium: Released to the aquatic environment primarily by surface erosion. The major human-related sources are from atmospheric deposition as a result of emissions associated with oil, gas and steel production.

Zinc: Enters the aquatic environment primarily as a result of geochemical weathering and industrial and municipal discharges. Zinc is an essential element for living organisms.


Nitrogen: An essential nutrient for the growth of plants. Only inorganic forms may be used by plants, specifically nitrate-nitrogen and ammonia-nitrogen, NH3-N (which includes the ammonium ion and free ammonia). Free ammonia, NH3, is toxic in aquatic ecosystems, but it is generally scarce except at high pH and temperature.

Phosphorus: An essential nutrient for the growth of plants. In aquatic systems, low phosphorus levels may limit plant productivity, whereas high levels may result in nuisance growth of aquatic plants. Phosphorus occurs in inorganic and organic compounds and in dissolved and particulate forms.

Silica: Refers to the oxides of silicon in water. It is present in most surface waters and originates primarily from weathering of aluminosilicate minerals. Silica is an essential nutrient for diatom algae.

Organic Constituents

Organic Carbon: The most abundant element found in all organisms. In aquatic environments, organic carbon is produced by plant photosynthesis and bacterial growth. Leaching of humic substances and decomposition of plants and animals are also natural sources of organic carbon to surface waters. Human-related sources include agricultural runoff and municipal and industrial effluents.

Pesticides: Chemical compounds used to control unwanted species that attack crops, animals and man. This diverse group of chemicals (organic and inorganic) includes herbicides, fungicides and insecticides.

PAHs: Polycyclic Aromatic Hydrocarbons are formed by the incomplete combustion of organic materials such as wood, coal and refuse. They are found in petroleum products and creosote and include compounds such as naphthalene, anthracene and benzo-a-pyrene.

Biological Characteristics

Bacteria: A diverse group of microorganisms that occur naturally in aquatic environments. Bacteria that occur naturally in surface water generally are not harmful to humans. But pathogenic bacteria can be introduced into surface waters from wastewater, particularly from municipal sewage effluents. Bacterial analyses include tests for fecal coliforms, total coliforms and fecal streptococci. These tests do not detect pathogenic bacteria directly, but are used as an indicator of possible contamination. The fecal coliform test is used to differentiate between coliforms of fecal origin (from warm-blooded animals) and coliforms from other sources.

Benthic Invertebrates: Animals that live on river and lake bottoms. Benthos refers to the bottom, and these animals are also called zoobenthos. Many of these inhabitants are immature stages of insects such as mayflies, stoneflies, caddisflies and midges. Other types of animals include aquatic earthworms or bristleworms, roundworms, leeches, snails, clams and crustaceans. The variety and abundance of benthic invertebrates in a river or lake usually reflects the type or condition of the habitats.

Chlorophyll-a: A photosynthetic pigment found in most algae, and concentrations of chlorophyll-a in a water sample provide a good estimate of the amount of algae suspended in the water. Chlorophyll-a may also be extracted from algae attached to rocks in the river.

Trophic Status: This term refers to the overall level of biological productivity (or fertility) of a lake and is usually defined by the concentrations of key nutrients (especially phosphorus) and planktonic algae (or phytoplankton) that are present. Alberta is a province with very diverse natural regions and as a result our lakes vary widely in trophic state. Some lakes, such as those in the mountains and higher elevation foothills regions, tend to have low nutrient concentrations. Others, like those in the boreal and parkland-prairie regions, tend to have higher or very high nutrient and algal concentrations.

Lakes in Alberta are categorized into four trophic levels:

  • Eutrophic (high productivity)
  • Hypereutrophic (very high productivity)
  • Mesotrophic (moderate productivity)
  • Oligotrophic (low productivity)

For an example of the trophic status graph, see:


Page Information

Updated: Jun 27, 2018