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Ice: A solid form
of water.
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Imhoff cone: A clear, cone-shaped
container used to measure the volume of settle able solids in a specific volume
of water.
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Immiscibility: The inability
of two or more solids or liquids to readily dissolve into one another.
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Impermeable: Material that
does not permit fluids to pass through.
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Impervious: The quality or
state of being impermeable; resisting penetration by water or plant roots. Impervious
ground cover like concrete and asphalt affects quantity and quality of runoff.
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Impoundment: A body of water
such as a pond, confined by a dam, dike, floodgate or other barrier. It is used
to collect and store water for future use.
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Impurities: Particles or
other objects that cause water to be unclear.
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Inchoate
water right:
An unperfected water right.
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Increasing
block rate: Pricing
that reduces water use by structuring water rates to increase per-unit charges
as the amount used increases.
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Indicator: Any biological
entity or process, or community whose characteristics show the presence of specific
environmental conditions or pollutants.
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Indicator
organisms: Microorganisms,
such as coliforms, whose presence is indicative of pollution or of more harmful
microorganism.
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Indicator
tests: Tests
for a specific contaminant, group of contaminants, or constituent which signals
the presence of something else (ex., coliforms indicate the presence of pathogenic
bacteria).
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Indirect
discharge: Introduction
of pollutants from a non-domestic source into a publicly owned wastewater treatment
system. Indirect dischargers can be commercial or industrial facilities whose
wastes enter local sewers.
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Industrial
wastewater facility:
Facilities that produce,
treat or dispose of wastewater not otherwise defined as a domestic wastewater;
includes the runoff and leachate from areas that receive pollutants associated
with industrial or commercial storage, handling, or processing.
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Industrial
water use: Water
used for industrial purposes such as fabrication, processing, washing, and cooling,
and includes such industries as steel, chemical and allied products, paper and
allied products, mining, and petroleum refining. The water may be obtained from
a public supply or may be self supplied. See also public supply and self- supplied
water.
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Infiltration: The movement
of water into soil or porous rock. Infiltration occurs as water flows through
the larger pores of rock or between soil particles under the influence of gravity,
or as a gradual wetting of small particles by capillary action.
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Inflow: The entry of
extraneous rainwater into a sewer system from sources other than infiltration,
such as basement drains, sewer holes, storm drains, and street washing.
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Influent: The stream of
water that enters any system or treatment unit.
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Inhibitor: chemical that
interferes with a chemical reaction, such as precipitation.
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Injection: The introduction
of a chemical or medium into the process water to alter its chemistry or filter
specific compounds.
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Inland freshwater
wetlands: Swamps,
marshes, and bogs found inland beyond the coastal saltwater wetlands.
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Inorganic: Matter other
than plant or animal and not containing a combination of carbon, hydrogen, and
oxygen, as in living things.
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Instream
flow: The amount
of flow required to sustain stream values, including fish, wildlife, and recreation.
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Instream
use: Water that
is used, but not withdrawn, from a ground- or surface-water source for such
purposes as hydroelectric power generation, navigation, water-quality improvement,
fish propagation, and recreation. Sometimes called non-withdrawal use or in-channel
use.
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Integrated
resource planning:
The management of two or
more resources in the same general area; commonly includes water, soil, timber,
grazing land, fish, wildlife, and recreation.
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Interbasin
transfer: The
diversion of water from one drainage basin to one or more other drainage basins.
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Interbasin
transfer: The
physical transfer of water from one watershed to another; regulated by the Texas
Water Code.
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Intermittent
flow system:
Alternating use, by an industry, of deionized water to remove contaminants from
products and equipment.
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Intermittent
stream: One that
flows periodically. Compare perennial stream.
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Interstate
water: According
to law, interstate waters are defined as (1) rivers, lakes and other waters
that flow across or form a part of state or international boundaries; (2) waters
of the Great Lakes; (3) coastal waters whose scope has been defined to include
ocean waters seaward to the territorial limits and waters along the coastline
(including inland streams) influenced by the tide.
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Interstices: The void or empty
portion of rock or soil occupied by air or water.
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Ion: An atom in a
solution that is charged, either positively (cations) or negatively (anions).
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Ion exchange: The replacement
of undesirable ions with a certain charge by desirable ions of the same charge
in a solution, by an ion-permeable absorbent.
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Irrigation: The controlled
application of water to cropland, hayland, and/or pasture to supplement that
supplied through nature.
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Irrigation
district: A cooperative,
self-governing public corporation set up as a subdivision of the State government,
with definite geographic boundaries, organized and having taxing power to obtain
and distribute water for irrigation of lands within the district; created under
the authority of a State legislature with the consent of a designated fraction
of the landowners or citizens.
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Irrigation
efficiency: The
percentage of water applied, and which can be accounted for, in the soil moisture
increase for consumptive use.
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Irrigation
field practices:
Techniques that keep water
in the field, more efficiently distribute water across the field, or encourage
the retention of soil moisture.
-
Irrigation
management strategies:
Strategies to monitor soil
and water conditions and collect information that helps in making decisions
about scheduling application or improving the efficiency of the irrigation system.
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Irrigation
return flow:
Water which is not consumptively used by plants and returns to a surface or
ground water supply. Under conditions of water right litigation, the definition
may be restricted to measurable water returning to the stream from which it
was diverted.
-
Irrigation
scheduling: Careful
choice of irrigation application rates and timing to help irrigators maintain
yields with less water.
-
Irrigation
system modification:
An addition to or an alteration
of an existing irrigation system or the adoption of a new one.
-
Irrigation
water: Water
which is applied to assist crops in areas or during times where rainfall is
inadequate.
-
Irrigation
water use: Artificial
application of water on lands to assist in the growing of crops and pastures
or to maintain vegetative growth in recreational lands such as parks and golf
courses.
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Isohyet: Line that connects
points of equal rainfall.
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Isotherm: Line that connects
points of equal temperature.
