Virginia Administrative Code › Title 9 - ENVIRONMENT › Agency 25 - STATE WATER CONTROL BOARD › Chapter 260 - WATER QUALITY STANDARDS › Part I - Surface Water Standards with General, Statewide Application › Section 9VAC25-260-5 - Definitions

Current through Register Vol. 40, No. 24, July 15, 2024
The following words and terms when used in this chapter
					 shall have the following meanings unless the context clearly indicates
					 otherwise:
"Algicides" means chemical substances, most commonly
					 copper-based, used as a treatment method to control algae growths.
"Board" means State Water Control Board. When used outside
					 the context of the promulgation of regulations, including regulations to
					 establish general permits, "board" means the Department of Environmental
					 Quality.
"Chesapeake Bay and its tidal tributaries" means all
					 tidally influenced waters of the Chesapeake Bay; western and eastern coastal
					 embayments and tributaries; James, York, Rappahannock and Potomac Rivers and
					 all their tidal tributaries to the end of tidal waters in each tributary (in
					 larger rivers this is the fall line); and includes subdivisions 1, 2, 3, 4, 5,
					 and 6 of
					 9VAC25-260-390,
					 subdivisions 1, 1b, 1d, 1f and 1o of
					 9VAC25-260-410,
					 subdivisions 5 and 5a of
					 9VAC25-260-415,
					 subdivisions 1 and 1a of
					 9VAC25-260-440,
					 subdivisions 2, 3, 3a, 3b and 3e of
					 9VAC25-260-520,
					 and subdivision 1 of
					 9VAC25-260-530.
					 This definition does not include free flowing sections of these waters.
"Criteria" means elements of the board's water quality
					 standards, expressed as constituent concentrations, levels, or narrative
					 statements, representing a quality of water that supports a particular use.
					 When criteria are met, water quality will generally protect the designated
					 use.
"Department" or "DEQ" means the Virginia Department of
					 Environmental Quality.
"Designated uses" means those uses specified in water
					 quality standards for each waterbody or segment whether or not they are being
					 attained.
"Drifting organisms" means planktonic organisms that are
					 dependent on the current of the water for movement.
"Epilimnion" means the upper layer of nearly uniform
					 temperature in a thermally stratified man-made lake or reservoir listed in
					 9VAC25-260-187
					 B.
"Existing uses" means those uses actually attained in the
					 waterbody on or after November 28, 1975, whether or not they are included in
					 the water quality standards.
"Lacustrine" means the zone within a lake or reservoir that
					 corresponds to nonflowing lake-like conditions such as those near the dam. The
					 other two zones within a reservoir are riverine (flowing, river-like
					 conditions) and transitional (transition from river to lake conditions).
"Man-made lake or reservoir" means a constructed
					 impoundment.
"Mixing zone" means a limited area or volume of water where
					 initial dilution of a discharge takes place and where numeric water quality
					 criteria can be exceeded but designated uses in the waterbody on the whole are
					 maintained and lethality is prevented.
"Natural lake" means an impoundment that is natural in
					 origin. There are two natural lakes in Virginia: Mountain Lake in Giles County
					 and Lake Drummond located within the boundaries of Chesapeake and Suffolk in
					 the Great Dismal Swamp.
"Passing organisms" means free swimming organisms that move
					 with a mean velocity at least equal to the ambient current in any
					 direction.
"Primary contact recreation" means any water-based form of
					 recreation, the practice of which has a high probability for total body
					 immersion or ingestion of water (examples include but are not limited to
					 swimming, water skiing, canoeing and kayaking).
"Pycnocline" means the portion of the water column where
					 density changes rapidly because of salinity and/or temperature. In an estuary
					 the pycnocline is the zone separating deep, cooler more saline waters from the
					 less saline, warmer surface waters. The upper and lower boundaries of a
					 pycnocline are measured as a change in density per unit of depth that is
					 greater than twice the change of the overall average for the total water
					 column.
"Secondary contact recreation" means a water-based form of
					 recreation, the practice of which has a low probability for total body
					 immersion or ingestion of waters (examples include but are not limited to
					 wading, boating and fishing).
"Swamp waters" means waters with naturally occurring low pH
					 and low dissolved oxygen caused by (i) low flow velocity that prevents mixing
					 and reaeration of stagnant, shallow waters and (ii) decomposition of vegetation
					 that lowers dissolved oxygen concentrations and causes tannic acids to color
					 the water and lower the pH.
"Use attainability analysis" means a structured scientific
					 assessment of the factors affecting the attainment of the use which may include
					 physical, chemical, biological, and economic factors as described in
					 9VAC25-260-10
					 H.
"Water quality standards" means provisions of state or
					 federal law which consist of a designated use or uses for the waters of the
					 Commonwealth and water quality criteria for such waters based upon such uses.
					 Water quality standards are to protect the public health or welfare, enhance
					 the quality of water and serve the purposes of the State Water Control Law
					 (§ 62.1-44.2 et seq. of the Code of Virginia) and the federal Clean Water
					 Act (
					 33 USC §
											1251 et seq.).
"Wetlands" means those areas that are inundated or
					 saturated by surface water or groundwater at a frequency and duration
					 sufficient to support, and that under normal circumstances do support, a
					 prevalence of vegetation typically adapted for life in saturated soil
					 conditions. Wetlands generally include swamps, marshes, bogs, and similar
					 areas.
Statutory Authority: § 62.1-44.15 of the Code of
						Virginia; Clean Water Act (33 USC §
													1251 et seq.); 40
						CFR Part 131.