General Glossary

A small change in a physical system.

Sites or conditions with slight anthropogenic perturbation
relative to the overall region.

an inorganic form of nitrogen, is contained in fertilizers,
septic system effluent,
and animal wastes. It is also a product of bacterial
decomposition of organic
matter. Ammonia NH3-N (NH3-N) becomes a concern if high levels
of the un-ionized form are
present. In this form NH3-N can be toxic to aquatic organisms.
The presence of
un-ionized ammonia is a function of the NH3-N concentration,
pH, and
temperature. Conversion of NH3-N to nitrite nitrogen by
nitrification requires

Any lake with total phosphorus (TP), chlorophyll-a, or Secchi
transparency data collected between 1970-1998, and stored under
MPCA's agency code 21 MINNL in STORET is included in this
assessment. Lakes were classified into one of two categories for
this data assessment. "M" implies monitored (recent) and
indicates that summer (June through September) data collected
between 1989 and 1998 was available for that lake. "E" implies
evaluated (old). This indicates that data for this lake was

CAS Number: 7439-97-6. Mercury is a naturally occurring metal
which has several forms. The metallic mercury is a shiny,
silver-white, odorless liquid. If heated, it is a colorless,
odorless gas. Mercury is known to be harmful to the central
nervous system, and is readily absorbed through the respiratory
tract, the gastrointestinal tract, and through unbroken skin.

Highest observation.

The amount of oxygen required by aerobic microorganisms to
decompose organic matter in a water sample, based on the maximum
rate of O2 consumption in a water sample over a five-day period
in the dark at 20 degrees C. It is used to estimate the total
amount of "biodegradable" organic matter in the
system and
therefore serves as a measure of the degree of water pollution.

Many organochlorine pesticides phased out since substantial use
began in the
1960's have properties that result in their increased
accumulation up the food
chain (bioaccumulation). Dichlorodiphenyl trichlororethane
(DDT), dieldrin, and
toxaphene are bioaccumulative pesticides that are no longer in
use in the
United States, but persist and are still detected in the
environment. Exposure
to bioaccumulative pesticides can affect nervous, reproductive,
and immune

Lead is a metal found naturally in the environment as well as
in
manufactured products. The major sources of lead emissions
have
historically been motor vehicles (such as cars and trucks) and
industrial sources. Due to the phase out of leaded gasoline,
metals processing is the major source of lead emissions to the
air today. The highest levels of lead in air are generally
found
near lead smelters. Other stationary sources are waste
incinerators, utilities, and lead-acid battery manufacturers.

Minnesota Department of Natural Resources lake identification
number. Lake ID numbers are taken from the Minnesota Department
of Natural Resources, 1968 publication "Bulletin 25: An
Inventory
of Minnesota Lakes." It is a six-digit code with the first two
digits indicating the county and the next four the lake number.
These numbers are used for storing/retrieving data in STORET
(EPA's STOrage and RETrieval database). Lakes with a 01, 02,
etc., suffix indicates that the lake has