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Glossary of Watershed Terms

Thursday, February 23, 2012

A work in progress, we hope this list of terms related to water and watershed management from The Doan Brook Handbook will provide general information and promote understanding of how we can steward our local natural resources.

Words used in definitions that are themselves included in the glossary are shown in italics.

anoxic   Lacking oxygen.

aquifer   A layer of soil or rock that is saturated and is capable of transmitting significant quantites of water. Some material, such as clay, can transmit very little water and will not generally be thought of as an aquifer. Other material, such as sand, gravel, or sandsone, can transmit significant quantities of water.

base flow    Flow in a stream during dry weather that is fed by groundwater seeping into the stream through its bed and banks.

bedrock    The layer of solid rock that underlies the surface soil. Bedrock in the upper Doan Brook watershed is sedimentary rock that lies a few feet below the surface. The sedimentary bedrock of the lower watershed lies several hundred feet below the surface.

benthic    Of or pertaining to the bottom of a body of water. (source: EPA)

biofiltration    The process of passing water through a concentrated colony of microorganisms that feed on contaminants found in the water. Biofiltration experiments on Doan Brook have used naturally occurring microbes to reduce the high concentrations of nutrients in the brook water.

BMP    Best Management Practice. BMPs for watershed management and development are the most effective and practical approaches to controlling point and non-point source pollution to levels that meet environmental quality goals.

cfs    Cubic feet per second. Cfs is the unit typically used to report the rate at which water flows past a given point in a culvert or stream.

channel    A stream or river bed; generally refers to the physical form where water commonly flows. (source: EPA)

channelization    The act of straightening a stream; typically widens and deepens the stream as well to improve the flow of water. (source: EPA)

coliform    A group of bacteria found in the intestines of warm-blooded animals (including humans), also in plants, soil, air, and water. Fecal coliforms are a specific class of bacteria that only inhabit the intestines of warm-blooded animals. The presence of coliforms is an indication that the water is polluted and may contain pathogenic organisms. (source: EPA)

combined sewer    A sewer line that carries both stormwater runoff and sanitary sewage.

confluence    The place where two streams meet.

CSO    Combined Sewer Overflow. Overflows of combined sewers to streams and lakes generally occur during wet weather, when the volume of stormwater is too large for the sewers to carry.

culvert    A pipe that carries a stream from one above-ground section to another above-ground section. For examples, the pipe that carries a stream under a road is a culvert as is the long pipe that carries Doan Brook beneath University Circle.

daylighting    Restoring a section of a stream that has been confined in a culvert or storm sewer to an above-ground channel.

Design Flood    The flood that a dam or other structure must, by regulation, be designed to safely withstand. The Design Flood for Horseshoe Lake dam and the Lower Shaker Lake dam is one half of the PMF.

drainage area or drainage basin    See watershed.

dredge spoil    Soil material that is removed (dredged) from the bottom of a lake or stream and then must be disposed of.

effluent    Wastewater, treated or untreated, that flows out of a treatment plant, sewer, or industrial point source, such as a pipe. Generally refers to wastes discharged into surface waters. (source:EPA)

erosion    The removal of sediment or rock from a point in the landscape. (soure: EPA)

escarpment    A long, cliff-like ridge of land or rock. The Portage Escarpment is a sharp fall in elevation that represents the westernmost edge of the Appalachian Plateau and separates the lower and upper Doan Brook watersheds.

eutrophic    Having high nutrient content and high biological activity. Refers specifically to lakes.

exotic species    Species of plants or animals that are not native to the area.

fissile    Geologic term referring to rock (generally shale) that breaks along parallel planes as it weathers, resulting in thin, plate-like fragments.

flood    An unusual accumulation of water above the ground caused by high tide, heavy rain, melting snow or rapid runoff from paved areas (source: EPA).  A ten-year flood is defined as a flood that has a one in ten chance of being equaled or exceeded in any given year.

gabions    Rock-filled wire baskets (generally square) that are stacked together to reinforce an eroding stream bank.

geomorphic process    A landscape altering system, such as water runoff or erosion, that influences the movement and shape of the physical landscape. 

glacial till    A soil made up of jumbled clay, silt, sand, gravel, and sometimes larger particles,, that was deposited in a relatively thin layer by glaciers as they retreated. Glacial till makes up much of the soil of the Doan Brook watershed.

green infrastructure     The management of stormwater runoff at the local level through the use of natural systems, or engineered systems that mimic natural systems, to treat polluted runoff. (source:EPA)

greenway    A strip of undeveloped land near an urban area, set aside for recreational use or environmental protection.

groundwater    Water that soaks into the soil and then flows within the matrix of soil or rock particles.  

headwaters    The upstream-most sections of a stream; the area where a stream originates.

hydrology    The science that deals with the circulation, distribution, and properties of the waters of the earth.

hypereutrophic    Having excessively high nutrient content and biological activity. Refers specifically to lakes. The dissolved oxygen content in the lakes is sometimes depleted by excessive plant growth, so that they support poor biologic communities.

impervious    Allowing little or no water to infiltrate; water tight. Paved areas and building roofs are the primary impervious surfaces in most urban watersheds.

impoundment    A lake, reservoir, or detention basin.

infiltrate    To filter into or through. Groundwater infiltrates into permeable material (like soil), but does not infiltrate through impervious surfaces (like pavement or rooftops).

interceptor sewer    A large sanitary sewer or combined sewer line that collects flow from a number of smaller sewers.

lacustrine    Originating in lake water. Lacustrine sediments are those deposited on lake bottoms.

lake plain    The relatively flat area adjacent to Lake Erie that once lay under the waters of the lake's ancestors. The Doan Brook lower watershed lies in the Lake Plain.

lower watershed    The part of the watershed extending from Lake Erie to the sharp change in elevation (the escarpment) just upstream (south and east) from University Circle.

macroinvertebrates    Invertebrates (animals without backbones) large enough to be seen without a microscope. The health of the macroinvertebrate population is an indicator of the water and habitat quality in a stream.

non-point source pollution    Pollution that originates from the accumulation of low concentrations of pollutants collected over a large area. Most of the nutrients that are discharged to Doan Brook accumulate from lawns and golf courses that are spread over the entire watershed. Nutrient contamination in the brook is thus the result of non-point source pollution.

nutrients    Essential chemicals needed by plants or animals for growth and health.  When nutrients are present in excessive quantities, they promote excessive plant growth that creates eutrophic or hypereutrophic conditions.

organic chemicals    Chemicals containing carbon. Naturally occurring organic chemicals are the basis of life on earth. However, in the context of water quality, "organics" generally refers to manmade carbon containing compounds such as synthetic oils, PCBs, poly-aromatic hydrocarbons (PAHs), pesticides, and herbicides that are often toxic and that often remain toxic for a long time when they are released into the environment.

overtopping    In the context of hydrology, overtopping refers to water flowing over the top of a dam or other water barrier, generally in a manner that the barrier is not intended to withstand. None of the Shaker Lakes dams are intended to withstand water flowing over its main earthen embankment.

pathogens    Microorganisms, such as bacteria, viruses, or parasites, that can cause disease in humans, animals, and plants. (source:EPA)

PCBs    Polychlorinate byphenyls. A group of manmade, toxic organic chemicals that persist in the environment and have been linked to cancer, reproductive defects, and other health problems.

permeable    Allowing water to infiltrate.

Plateau    Generally refers to a level land area raised above the surrounding land. The westernmost edge of the Appalachian Plateau forms the Doan Brook upper watershed, and terminates at the Escarpment.

PMF    Probable Maximum Flood.

point source pollution    Pollution that originates at a single location, such as a factory waste discharge pipe.

Probable Maximum Flood    The Probable Maximum Flood, or PMF, is defined as "...the flood that can be expected from the most severe combination of critical meteorologic and hydrologic conditions that are reasonably possible..." in a given area (National Research Council, 1988). In other words the worst flood that can be imagined if science is used to guide the imagination.

QHEO    Qualitative Habitat Evaluation Index. A physical habitat index designed to provide an empirical, quantified evaluation of the general stream microhabitat characteristics that are important to fish communities.

riparian    Having to do with the bank of a river. Used to refer generally to the area surrounding any natural body of water.

riparian corridor    The strip of land immediately adjacent to and including a stream. A riparian corridor that is left in its natural condition protects the stream's water quality and habitat.

riprap    Large rocks that are dumped or placed to prevent erosion. The downstream face of Horseshoe Lake dam has been armored by riprap.

runoff    Water that flows along the surface of the land.

sandstone    A sedimentary rock composed of sand particles cemented together.

sanitary sewage    Wastewater (sewage) collected from households and businesses.

sanitary sewer    A sewer that is designed to carry only sewage collected from household and business indoor drainage systems. Sanitary sewers are not intended to collect stormwater runoff.

sediment    Particulate material suspended in or settled to the bottom of a water body. Sediment may originate from natural sources such as natural soil erosion or from human activity such as construction, road grit, disturbed land, or agriculture. Increased flow in an urban stream like Doan Brook also increases the quantity of sediment eroded from the stream bed and banks.

sedimentary rock    A rock formed by the accumulation and cementation of mineral (sand, silt, clay, etc.) grains. Sedimentary rocks are generally formed when layers of material that were deposited over many years by wind or water are subsequently buried and compressed until they become rock.

sedimentation    Deposition of sediments in lakes or other areas of relatively still water. Over time, lake sedimentation degrades lake habitat and transforms lakes into marshes and eventually valleys. Lake sedimentation rarely changes a lake's ability to decrease downstream flooding.

sewershed    The area that drains into a sanitary or combined sewer system. The sewershed is generally related to the surface watershed, but it need not correspond exactly.

shale    A very fine-grained sedimentary rock composed of silt and clay. Shale tends to break apart along planes parallel to the plane in which the silt or clay was originally deposited. As a result, shale frequently weathers into thi plate-like fragments.

stakeholder    Individual or organization that has a stake in the outcome of the watershed plan.

storm sewer    A sewer designed to carry stormwater runoff without any mixture of sanitary sewage.


stormwater    Runoff that flows from the surface of the watershed during a storm.

stream gauge    An instrument to measure the volume of streamflow over time, generally reported in cubic feet per second (cfs).

stream reach    A continuous portion of a stream between two designated points. (source:EPA)


surface runoff    See runoff.

stormwater retrofit    Stormwater retrofits are new stormwater control structures (small or large) designed to reduce flooding or improve water quality. They are retrofit into already developed areas.

subwatershed    A small area of a larger watershed for which surface runoff drains to a particular point. The area that drains to Horseshoe Lake is an example of a subwatershed within the Doan Brook watershed. The area that drains to the lower Shaker Lake is another subwatershed that contains the Horseshoe Lake subwatershed.

till    See glacial till.

TMDL    Total Maximum Daily Load. Generally refers to plans under the Clean Water Act that limit the amount of pollutant discharge over time. (source:EPA)

uncontrolled drainage areas    Drainage areas (or watersheds) that do not include a lake or other structure that reduces flood peaks or slows storm runoff.

upper watershed    The part of the Doan Brook watershed that lies on the higher elevation land east of the line of the Escarpment.

watershed    A stream's watershed is the area of land over which water running along the ground surface (called runoff or surface runoff) will eventually flow into the stream. Also called a drainage area or drainage basin.