Environmental Engineering Reference
In-Depth Information
Mean discharge: The arithmetic mean of individual daily mean discharges
of a stream during a specific period, usually daily, monthly, or
a n nu a l ly.
Membrane filter method: A laboratory method used for coliform testing. The
procedure uses an ultrathin filter with a uniform pore size smaller
than bacteria (less than a micron). After water is forced through the
filter, the filter is incubated in a medium that promotes the growth
of coliform bacteria. Bacterial colonies with a green-gold sheen indi-
cate the presence of coliform bacteria.
Method detection limit: The minimum concentration of a substance that can
be accurately identified and measured with current lab technologies.
Midge: A small fly in the family Chironomidae. The larval (juvenile) life
stages are aquatic.
Minimum reporting level (MRL): The smallest measured concentration of
a constituent that may be reliably reported using a given analytical
method. In many cases, the MRL is used when documentation for
the method detection limit is not available.
Mitigation: Actions taken to avoid, reduce, or compensate for the effects of
human-induced environmental damage.
Modes of transmission of disease: The ways in which diseases spread from
one person to another.
Monitoring: Repeated observation, measurement, or sampling at a site, on a
scheduled or event basis for a particular purpose.
Monitoring well: A well designed for measuring water levels and testing
groundwater quality.
Multiple-tube fermentation method: A laboratory method used for coli-
form testing, which uses a nutrient broth placed in culture tubes.
Gas production indicates the presence of coliform bacteria.
N
National Pollutant Discharge Elimination System (NPDES): Permit pro-
gram authorized by the Clean Water Act that controls water pollu-
tion by regulating discharges to any water body. It sets the highest
permissible effluent limits prior to making any discharge.
National Primary Drinking Water Regulations (NPDWRs): Regulations
developed under the Safe Drinking Water Act that establish maxi-
mum contaminant levels, monitoring requirements, and report-
ing procedures for contaminants in drinking water that endanger
human health.
Near Coastal Water Initiative: Initiative developed in 1985 to provide for
management of specific problems in waters near coastlines that are
not dealt with in other programs.
Nitrate: An ion consisting of nitrogen and oxygen (NO 3 ). Nitrate is a plant
nutrient that is very mobile in soils.
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