Best Management Practice (BMP)
A practice or combination of practices that prevent or reduce adverse affects of stormwater runoff and/or associated pollutants.
Cylindrical samples of soil profile used to determine infiltration capacity of soil types and ground water.
A zone where plantings capable of filtering stormwater are established or preserved and where construction, paving and chemical applications are prohibited.
A collection structure below ground designed to collect and convey water into the storm sewer system. It is designed so that sediment falls to the bottom of the catchbasin and not directly into the pipe.
Calhoun County Road Commission
An earthen, rock or log structure used in grass swales to reduce water velocities, promote sediment deposition and enhance infiltration.
An open or enclosed stormwater conveyance system that is under the legal jurisdiction of the Water Resources Commissioner for construction, operation and maintenance.
A conduit used for the passage of surface water under a road or other embankment.
Department of Natural Resources - Environment
A rainfall event of specified size and return frequency(i.e., a storm what has the likelihood of occurring once every 10 or 100 years) that is used to calculate the runoff volume and peak discharge rate.
The temporary storage of storm runoff to control peak discharge rates and provide gravity settling of pollutants.
An area designated to temporarily store storm runoff so a controlled outflow can slowly empty the area.
The amount of time that a volume of water will remain in a detention basin.
Anyone who organizes the actual development of land and may or may not be the landowner.
The rate of flow(the volume of water passing a point in a given period of time) leaving an area usually expressed as cubic feet per second.
The total tributary area of a watershed usually expressed in square miles, acres or square feet.
Any facility used to transport or store stormwater.
The gradual reduction in water level in a basin due to the combined effect of infiltration and evaporation.
Easement (also know as a "Right-of-Way")
A legal right granted by a property owner to another entity giving that entity limited use of the property involved for a specific purpose. The Water Resources Commissioner secures temporary and permanent easements adjacent to county drains for the purpose of construction and maintenance access.
The wearing away of the land surface by wind, water, ice and gravity dislodging soil particles. Evidence of erosion are gullies, rills, sediment, plumes, etc.
Added earth which changes the contour of the land.
Textile or relatively small mesh or pore size that is used to 1) allow water to pass through while keeping sediment out (permeable), or 2) prevent both runoff and sediment from passing through (impermeable).
The delivery of a highly concentrated pollutant loading during the early stages of a storm due to the washing effect of runoff on pollutants that have accumulated on the land.
For a given flood event that area of land adjoining a continuous watercourse that has been covered temporarily by water.
The space from the top of an embankment to the highest water elevation expected for the largest design storm to be stored. The space is required as a safety margin in a pond or basin.
A woven fabric capable of passing water but able to hold back soil.
Naturally existing water beneath the earth’s surface between saturated soil particles and rock that supplies wells and springs.
The upper surface or top of the saturated portion of the soil or bedrock layer that indicates the uppermost extent of groundwater.
The absorption of water into the ground expressed in terms of inches/hour.
The maximum rate at which the soil can absorb falling rain or melting snow. Usually expressed in inches/hour or centimeters/second.
The interior surface of the bottom of any pipe.
A structure that allows access into a stormwater drainage system.
A natural or artificial layer of plant residue which aids in seedling germination by reducing the temperature fluctuations, holding moisture and holding soil in place.
Land characterized by the natural presence of water sufficient to support wetland vegetation.
Non-Point Source Pollution
Pollution that is not identifiable to any particular source as described by the NREPA.
Natural Resources & Environmental Protection Act, Act 451 of the Public Acts of 1994, as amended.
Detention provided at a regional detention facility as opposed to storage on-site.
Where stormwater is detained on a site verses a regional location.
One Hundred Year Flood
A flood that has one percent (1%) chance occurring in any given year.
Ordinary High Water Mark
The line between upland and bottomland which persist through successive changes in water level below which the presence of water is so common or recurrent that the character of the soil and vegetation is markedly different from the upland.
The maximum instantaneous rate of flow during a storm usually in reference to a specific design storm event.
Ability to absorb water.
A legal request to the Water Resources Commissioner to perform a maintenance improvement or construction.
A legal procedure whereby a larger piece of property is divided into smaller sections and is accompanied by a full description of the original property the dimension of each lot to be subdivided and all relevant deed restrictions and easements as described in the Land Division Act.
A professional engineer licensed in Michigan that performs the engineering design for the development.
Any person, firm, association, partnership, corporation or any combination thereof that owns property proposed for development.
Any wetland protected by state law or local government regulation.
A simple technique for estimating peak discharge rates for very small developments based on the rainfall intensity, watershed time of concentration and runoff coefficient.
The holding of runoff in a basin without release except by means of evaporation, infiltration or emergency bypass.
A stormwater management basin that captures storm water runoff and does not discharge directly to a surface water body. The water is "discharged" by infiltration or evaporation.
A combination of large stone, cobbles and boulders used to line channels, stabilize banks, reduce runoff velocities or filter out sediment.
1. A vertical pipe extending from the bottom of a basin that is used to control the discharge rate from the basin for a specified design storm.
2. A pipe rising from underground tile to allow surface water to enter the tile in a low area.
The excess portion of precipitation that does not infiltrate into the ground but "runs off" and reaches a stream, water body or storm sewer.
The ratio of the amount of water that is NOT absorbed by the surface to the total amount of water that falls during a rainstorm.
Seasonal High Water Ground Level
The highest level of groundwater that occurs frequently enough for the water to stain the soils.
Soil material that is transported from its site of origin by water. May be in the form of bed load (along the bed), suspended or dissolved.
Runoff which flows over the ground surface as a thin even layer, not concentrated in a channel or pipe.
Soil Group, Hydrologic
A classification of soils by the Natural Resource Conservation Service into four runoff potential groups. The groups range from A soils, which are very permeable and produce little runoff, to D soils which are not very permeable and produce much more runoff.
A depression in the embankment of a pond or basin used to pass peak discharges in excess of the design storm.
By MDNR definition; "a river, creek, or surface waterway that may or may not be defined by Act 40, P.A. Of 1956: has definite banks, a bed, and visible evidence of continued flow or continued occurrence of water, including the connecting water of the Great Lakes".
A natural depression or wide shallow ditch used to temporarily convey, store, or filter runoff.
Time Of Concentration
The time it takes for surface runoff to travel from the hydraulically farthest portion of the watershed to the design point.
The entire land, including adjacent property that produces runoff to a given point in the stormwater conveyance system or a storage basin.