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Monitoring and Assessment Glossary Algal bloom: An unusual or excessive abundance of algae. Assessment: An evaluation that compares recent water quality information for a given lake or stream to water quality standards to determine if beneficial uses (aquatic recreation, aquatic consumption, etc.) are being supported. Assessment year: The calendar year in which the assessment decisions were determined. Beneficial use: A designation, set in law, of the public uses and benefits a given lake or stream reach provide to people (examples below). In addition to the text, a number is assigned to uses. In addition to the text, a number is assigned to uses. Typically, a lake or stream reach is protected for multiple beneficial uses. For more information: http://www.pca.state.mn.us/gp0r909. • Aquatic recreation use (Class 2) (lakes): Lakes are assessed to determine if water quality meets thresholds set for protecting aquatic recreation uses, such as swimming and wading. In general, too much algae in a lake is what makes it undesirable for recreation. Data considered during the assessment process include total phosphorus (nutrient), chlorophyll-a (measure of algae), and Secchi depth (water clarity). • Aquatic recreation use (Class 2) (streams): Streams are assessed to determine if water quality meets thresholds set for protecting aquatic recreation uses, such as swimming and wading. E. coli levels are currently used to determine aquatic recreation use support in streams. In general, if bacteria levels exceed thresholds, the possibility of illness from water contact increases. • Aquatic life use (Class 2) (lakes): Lakes are assessed to determine if water quality meets thresholds set for protecting aquatic life uses, such as supporting a healthy fish and aquatic plant community. At this time, the MPCA is assessing lakes for aquatic life based on chloride concentrations. Future assessments will include an evaluation of aquatic plant and fish populations directly. • Aquatic life use (Class 2) (streams): Streams are assessed to determine if water quality meets thresholds set for protecting aquatic life uses, such as supporting a healthy fish and aquatic insect community. A variety of parameters affect aquatic life: dissolved oxygen, suspended sediment, toxics (e.g. chloride, ammonia), and pesticides. Biological communities (fish and aquatic insect) are sampled and, with water chemistry data above, are used to determine if aquatic life is being supported. • Aquatic consumption use (Class 2) (lakes and streams): Fish are sampled in both lakes and streams to determine if they are fit for human consumption. In general, if polychlorinated biphenyls, perfluorooctane sulfonate, or mercury exceed safe levels in the fish tissue, restrictive consumption guidelines are developed for fish from that resource and the lake or stream reach is considered impaired for aquatic consumption. The Minnesota Department of Health is responsible for determining fish consumption guidelines. • Drinking water use (Class 1) (streams): Streams with this designated use are sampled to determine if they meet the existing standard for nitrate-nitrite. This is the only constituent the standard applies to at this time; as a result, the MPCA does not consider any stream to be fully supporting for drinking water use, as our monitoring design does not include all possible parameters. • Limited value resource waters use (Class 7) (streams): Altered streams (e.g. ditches) with this designation are protected against excess toxics (chloride, ammonia, metals), excess bacteria, extreme pH, and low dissolved oxygen.
Minnesota Pollution Control Agency April 2012 | wq-cm5-01 651-296-6300 | 800-657-3864 | TTY 651-282-5332 or 800-657-3864 Available in alternative formats
Chlorophyll-a: A pigment produced by algae (and other plants). Chlorophyll-a is measured in a water sample and is used as an estimate of the amount (biomass) of algae in water. Ecoregion: Areas of relative homogeneity. U. S. Environmental Protection Agency ecoregions have been defined for Minnesota based on land use, soils, landform, and potential natural vegetation. Minnesota has seven of these ecoregions: Northern Lakes and Forests (NLF), North Central Hardwood Forests (NCHF), Northern Minnesota Wetlands (NMW), Western Corn Belt Plains (WCBP), Northern Glaciated Plains (NGP), Driftless Area (DA), and Lake Agassiz Plain (LAP). Eutrophication: The aging process by which lakes are fertilized with nutrients. Natural eutrophication will very gradually change the character of a lake. Cultural eutrophication is the accelerated aging of a lake as a result of human activities. Eutrophic lake: A nutrient-rich lake - usually shallow, "green" and with limited oxygen in the bottom layer of water. Hypereutrophic lake: A very nutrient-rich lake characterized by frequent and severe nuisance algal blooms and low transparency. Impairment: A lake or stream is impaired if it fails to meet one or more of Minnesota's water quality standards. Impairment cause: Parameter determined to be limiting the beneficial use of a waterbody. Examples include low dissolved oxygen for streams or excess nutrients for lakes. Lake catchment: The surrounding land area that drains into a given lake. Land use: The type of cover currently in place, such as cultivated, forested, open water, or urban. Mesotrophic lake: Midway in nutrient levels between the eutrophic and oligotrophic lakes. Oligotrophic lake: A relatively nutrient-poor lake, it is clear and deep with bottom waters high in dissolved oxygen. Parameter: A single water quality component that can be sampled for, such as dissolved oxygen or phosphorus. Phosphorus: An essential plant nutrient. Excess quantities promote excessive growth of algae and plants in lakes and streams, and the primary element associated with eutrophication. Total phosphorus refers to the most common form measured in water and includes both dissolved and particulate phosphorus. Restoration project: A plan that determines reductions needed to restore water quality so that an impaired water body can meet the designated beneficial use to which it is assigned. Secchi disk: A round white or white and black disk that is lowered into a lake to measure water transparency. Station: A location where water sampling has taken place. Transparency: The amount of light penetrating the water, measured in lakes with a Secchi disk. Transparency is an indication of the amount of algae in the water. Trends: Analysis of change in a data set; increasing, decreasing or no change. For lakes and streams, the MPCA calculates trends for Secchi transparency and Secchi tube transparency, respectively. Trophic State Index: The level of growth or productivity of a lake as measured by phosphorus content, algae abundance, and depth of light penetration (Secchi). Ranging from low productivity (oligotrophic) to high productivity (hypereutrophic) Water quality standards: Water quality thresholds, set in statute that must be met to protect the beneficial uses that have been assigned to a lake or stream reach. For more information: http://www.pca.state.mn.us/gp0r909. Watershed: The surrounding land area that drains into a lake, river, or river system.
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