Escherichia coli, a subgroup of fecal coliform bacteria that is
present in the intestinal tracts and feces of warm-blooded
animals. It is used as an indicator of the potential presence of
pathogens. There are many different strains of E. coli that are
classified into more than 170 serogroups. Although most strains
of E. coli are harmless and live in the intestines of healthy
humans and animals, the E. coli O157:H7 strain produces a
powerful toxin and can cause severe illness.

A measure of the relative acidity or alkalinity of water. The pH
scale ranges from 1 to 14, with 1 being the most acidic and 14
the most alkaline. Pure water is neutral with a pH of 7.

Indicates the degree to which light is scattered in water by
suspended particulate material and soluble colored compounds. It
provides an estimate of the muddiness or cloudiness of the water
due to clay, silt, finely divided organic and inorganic matter,
soluble colored organic compounds, plankton, and microscopic
organisms.

A degradation product of chlorophyll-a that interferes with the
measurement of chlorophyll-a, resulting in its over- or
under-estimation. Pheophytin-a measurements help to determine a
more accurate measure of chlorophyll-a.

Sample collection depth measured from the surface of a lake.

The depth in a lake, measured in meters, to which a Secchi disk
can be observed, as a measure of light penetration in water. The
Secchi disk is lowered into a section of shaded water until it
can no longer be seen and then lifted back up until it can be
seen once again. Averaging the two depths gives the clarity of
the water

A nutrient essential to the growth of organisms, and is commonly
the limiting factor in the primary productivity of surface water
bodies. Total phosphorus includes the amount of phosphorus in
solution (reactive) and in particle form. Agricultural drainage,
wastewater, and certain industrial discharges are typical sources
of phosphorus, and can contribute to the eutrophication of
surface water bodies. Measured in milligrams per liter (mg/L).

The transparency of stream water (in units of centimeters) as
measured in a Citizen Stream Monitoring Program transparency
tube. The transparency tube is a clear, 60 cm-long tube with
colored disk on the bottom for measuring depth at which disk is
visible. The clarity of stream water is an indicator of how much
sediment, algae, and other materials are suspended in the water.

The number of vehicles that could be receiving gasoline
simultaneously at a gasoline service station.

A closed system of pipes, hoses, and fittings, connecting a
gasoline-unloading tank and a gasoline-receiving tank at a
gasoline service station so that the vapors displaced from the
receiving tank are transferred to the unloading tank.