Current through Register Vol. 60, No. 12, December 1, 2021
Definitions in this rule apply to all basins unless context
Quality Certification" means a determination made by DEQ that a dredge and fill
activity, private hydropower facility, or other federally licensed or permitted
activity that may result in a discharge to waters of the state has adequate
terms and conditions to prevent an exceedance of water quality criteria. The
federal permit in question may not be issued without this state determination
in accordance with the Federal Clean Water Act, section 401 ( 33 USC 1341
(2) "Ambient Stream Temperature"
means the stream temperature measured at a specific time and place. The
selected location for measuring stream temperature must be representative of
the stream in the vicinity of the point being measured.
(3) "Anthropogenic," when used to describe
"sources" or "warming," means that which results from human activity.
(4) "Applicable Criteria" means
the biologically based temperature criteria in OAR
the superseding cold water protection criteria in
or the superseding natural condition criteria in
The applicable criteria may also be site-specific criteria approved by U.S.
EPA. A subbasin may have a combination of applicable temperature criteria
derived from some or all of these numeric and narrative criteria.
(5) "Appropriate Reference Site or Region"
means a site on the same water body or within the same basin or ecoregion that
has similar habitat conditions and represents the water quality and biological
community attainable within the areas of concern.
(6) "Aquatic Species" means plants or animals
that live at least part of their life cycle in waters of the state.
(7) "Basin" means a third-field hydrologic
unit as identified by the U.S. Geological Survey.
(8) "BOD" means 5-day, 20°C Biochemical
Aquatic Life" means aquatic organisms that are physiologically restricted to
cold water including, but not limited to, native salmon, steelhead, mountain
whitefish, char including bull trout, and trout.
(10) "Cold Water Refugia" means those
portions of a water body where or times during the diel temperature cycle when
the water temperature is at least 2 degrees Celsius colder than the daily
maximum temperature of the adjacent well-mixed flow of the water body.
(11) "Commission" or "EQC" means
the Oregon Environmental Quality Commission.
(12) "Cool Water Aquatic Life" means aquatic
organisms that are physiologically restricted to cool waters including, but not
limited to, native sturgeon, Pacific lamprey, suckers, chub, sculpins and
certain species of cyprinids (minnows.)
(13) "Core Cold Water Habitat Use" means
waters expected to maintain temperatures within the range generally considered
optimal for salmon and steelhead rearing, or that are suitable for bull trout
migration, foraging and sub-adult rearing that occurs during the summer. These
uses are designated on the following subbasin maps set out at OAR
Figures 130A, 151A, 160A, 170A, 180A, 201A, 220A, 230A, 271A, 286A, 300A, 310A,
320A, and 340A.
Habitat" means those areas that support rare, threatened, or endangered species
or serve as sensitive spawning and rearing areas for aquatic life as designated
by the U.S. Fish and Wildlife Service or National Oceanic and Atmospheric
Administration-Fisheries according to the Endangered Species Act (16 U.S. C
(15) "Daily Mean"
for dissolved oxygen means the numeric average of an adequate number of data to
describe the variation in dissolved oxygen concentration throughout a day,
including daily maximums and minimums. For calculating the mean, concentrations
in excess of 100 percent of saturation are valued at the saturation
or "DEQ" means the Oregon State Department of Environmental Quality.
(17) "Designated Beneficial Use" means the
purpose or benefit to be derived from a water body as designated by the Water
Resources Department or the Water Resources Commission.
(18) "DO" means dissolved oxygen.
(19) "Ecological Integrity" means the
summation of chemical, physical, and biological integrity capable of supporting
and maintaining a balanced, integrated, adaptive community of organisms having
a species composition, diversity, and functional organization comparable to
that of the natural habitat of the region.
(20) "Epilimnion" means the seasonally
stratified layer of a lake or reservoir above the metalimnion; the surface
(21) "Erosion Control Plan"
means a plan containing a list of best management practices to be applied
during construction to control and limit soil erosion.
(22) "Estuarine Waters" means all mixed fresh
and oceanic waters in estuaries or bays from the point of oceanic water
intrusion inland to a line connecting the outermost points of the headlands or
Quality Waters" means those waters that meet or exceed levels necessary to
support the propagation of fish, shellfish and wildlife; recreation in and on
the water; and other designated beneficial uses.
(24) "Hypolimnion" means the seasonally
stratified layer of a lake or reservoir below the metalimnion; the bottom
(25) "Industrial Waste"
means any liquid, gaseous, radioactive, or solid waste substance or a
combination thereof resulting from any process of industry, manufacturing,
trade, or business or from the development or recovery of any natural
(26) "In Lieu Fee"
means a fee collected by a jurisdiction in lieu of requiring construction of
onsite stormwater quality control facilities.
(27) "Intergravel Dissolved Oxygen" (IGDO)
means the concentration of oxygen measured in the water within the stream bed
gravels. Measurements should be taken within a limited time period before
emergence of fry.
"Jurisdiction" means any city or county agency in the Tualatin River and Oswego
Lake subbasin that regulates land development activities within its boundaries
by approving plats or site plans or issuing permits for land development.
(29) "Land Development" means any
human-induced change to improved or unimproved real estate including, but not
limited to, construction, installation or expansion of a building or other
structure; land division; drilling; or site alteration such as land surface
mining, dredging, grading, construction of earthen berms, paving, improvements
for use as parking or storage, excavation or clearing.
(30) "Load Allocation" or "LA" means the
portion of a receiving water's loading capacity that is attributed either to
one of its existing or future nonpoint sources of pollution or to natural
background sources. Load allocations are best estimates of the loading that may
range from reasonably accurate estimates to gross allotments, depending on the
availability of data and appropriate techniques for predicting loading.
Whenever possible, natural and nonpoint source loads should be distinguished.
(31) "Loading Capacity" or "LC"
means the greatest amount of loading that a water body can receive without
violating water quality standards.
(32) "Low Flow Period" means the flows in a
stream resulting primarily from groundwater discharge or base flows augmented
from lakes and storage projects during the driest period of the year. The dry
weather period varies across the state according to climate and topography.
Wherever the low flow period is indicated in Water Quality Management Plans,
this period has been approximated by the inclusive months. Where applicable in
a waste discharge permit, the low flow period may be further defined.
(33) "Managed Lakes" refers to
lakes in which hydrology is managed by controlling the rate or timing of inflow
(34) "Marine Waters"
means all oceanic, offshore waters outside of estuaries or bays and within the
territorial limits of the State of Oregon.
(35) "mg/l" or "mg/L" means milligrams per
(36) "Metalimnion" means
the seasonal, thermally stratified layer of a lake or reservoir that is
characterized by a rapid change in temperature with depth and that effectively
isolates the waters of the epilimnion from those of the hypolimnion during the
period of stratification; the middle layer.
(37) "Migration Corridors" mean those waters
that are predominantly used for salmon and steelhead migration during the
summer and have little or no anadromous salmonid rearing in the months of July
and August. Migration corridors are designated in Tables 101B and 121B and
Figures 151A, 170A, 300A and 340A under OAR
(38) "Minimum" for dissolved
oxygen means the minimum recorded concentration including seasonal and diurnal
(39) "Monthly (30-day)
Mean Minimum" for dissolved oxygen means the minimum of the 30 consecutive-day
floating averages of the calculated daily mean dissolved oxygen concentration.
(40) "Natural Conditions" means
conditions or circumstances affecting the physical, chemical, or biological
integrity of a water of the state that are not influenced by past or present
anthropogenic activities. Disturbances from wildfire, floods, earthquakes,
volcanic or geothermal activity, wind, insect infestation and diseased
vegetation are considered natural conditions.
(41) "Natural Thermal Potential" means the
determination of the thermal profile of a water body using best available
methods of analysis and the best available information on the site-potential
riparian vegetation, stream geomorphology, stream flows and other measures to
reflect natural conditions.
"Nonpoint Sources" means any source of water pollution other than a point
source. Generally, a nonpoint source is a diffuse or unconfined source of
pollution where wastes can either enter into waters of the state or be conveyed
by the movement of water into waters of the state.
(43) "Ocean Waters" means all oceanic,
offshore waters outside of estuaries or bays and within the territorial limits
Resource Waters" means waters designated by the EQC where existing high quality
waters constitute an outstanding state or national resource based on their
extraordinary water quality or ecological values or where special water quality
protection is needed to maintain critical habitat areas.
(45) "Pollution" means such contamination or
other alteration of the physical, chemical, or biological properties of any
waters of the state, including change in temperature, taste, color, turbidity,
silt, or odor of the waters, or such discharge of any liquid, gaseous, solid,
radioactive, or other substance into any water of the state that either by
itself or in connection with any other substance present can reasonably be
expected to create a public nuisance or render such waters harmful,
detrimental, or injurious to public health, safety, or welfare; to domestic,
commercial, industrial, agricultural, recreational, or other legitimate
beneficial uses; or to livestock, wildlife, fish, other aquatic life or the
Source" means a discernible, confined, and discrete conveyance including, but
not limited to, a pipe, ditch, channel, tunnel, conduit, well, discrete
fissure, container, rolling stock, concentrated animal feeding operation,
vessel or other floating craft, or leachate collection system from which
pollutants are or may be discharged. Point source does not include agricultural
storm water discharges and return flows from irrigated agriculture.
(47) "Public Water" means the same as "waters
of the state".
(48) "Public Works
Project" means any land development conducted or financed by a local, state, or
federal governmental body.
"Reserve Capacity" means that portion of a receiving stream's loading capacity
that has not been allocated to point sources or to nonpoint sources and natural
background as waste load allocations or load allocations, respectively. The
reserve capacity includes that loading capacity that has been set aside for a
safety margin and is otherwise unallocated.
(50) "Resident Biological Community" means
aquatic life expected to exist in a particular habitat when water quality
standards for a specific ecoregion, basin or water body are met. This must be
established by accepted biomonitoring techniques.
(51) "Salmon" means chinook, chum, coho,
sockeye and pink salmon.
"Salmon and Steelhead Spawning Use" means waters that are or could be used for
salmon and steelhead spawning, egg incubation, and fry emergence. These uses
are designated on the following subbasin maps set out at OAR
Tables 101B, and 121B, and Figures 130B, 151B, 160B, 170B, 220B, 230B, 271B,
286B, 300B, 310B, 320B, and 340B.
(53) "Salmon and Trout Rearing and Migration
Use" means thermally suitable rearing habitat for salmon, steelhead, rainbow
trout, and cutthroat trout as designated on subbasin maps set out at OAR
Figures 130A, 151A, 160A, 170A, 220A, 230A, 271A, 286A, 300A, 310A, 320A, and
(54) "Salmonid or Salmonids"
means native salmon, trout, mountain whitefish and char including bull trout.
For purposes of Oregon water quality standards, salmonid does not include brook
or brown trout because they are introduced species.
"Secondary Treatment" means the
following depending on the context:
sewage wastes, secondary treatment means the minimum level of treatment
mandated by U.S. Environmental Protection Agency regulations pursuant to Public
(b) For industrial and
other waste sources, secondary treatment means control equivalent to best
(56) "Seven-Day Average Maximum Temperature"
means a calculation of the average of the daily maximum temperatures from seven
consecutive days made on a rolling basis.
(57) "Sewage" means the water-carried human
or animal waste from residences, buildings, industrial establishments, or other
places together with such groundwater infiltration and surface water as may be
present. The admixture with sewage of industrial wastes or wastes, as defined
in this rule, may also be considered "sewage" within the meaning of this
Disturbance" means a temporary disturbance of six months or less when water
quality standards may be violated briefly but not of sufficient duration to
cause acute or chronic effects on beneficial uses.
(59) "Spatial Median" means the value that
falls in the middle of a data set of multiple intergravel dissolved oxygen
(IGDO) measurements taken within a spawning area. Half the samples should be
greater than and half the samples should be less than the spatial median.
(60) "SS" means suspended solids.
(61) "Stormwater Quality Control
Facility" means any structure or drainage way designed, constructed and
maintained to collect and filter, retain, or detain surface water runoff during
and after a storm event for the purpose of water quality improvement. It may
also include, but is not be limited to, existing features such as wetlands,
water quality swales and ponds maintained as stormwater quality control
(62) "Subbasin" means
a fourth-field hydrologic unit as identified by the U.S. Geological Survey.
(63) "Summer" means June 1 through
September 30 of each calendar year.
"Threatened or Endangered Species" means
aquatic species listed as either threatened or endangered under the federal
Endangered Species Act (16 U.S. C
ode ¦ 1531 et seq. and Title 50 of the
Code of Federal Regulations).
"Total Maximum Daily Load (TMDL)" means the sum of the individual waste load
allocations (WLAs) for point sources and load allocations (LAs) for nonpoint
sources and background. If receiving water has only one point source
discharger, the TMDL is the sum of that point source WLA plus the LAs for any
nonpoint sources of pollution and natural background sources, tributaries, or
adjacent segments. TMDLs can be expressed in terms of either mass per time,
toxicity, or other appropriate measure. If Best Management Practices (BMPs) or
other nonpoint source pollution controls make more stringent load allocations
practicable, then wasteload allocations can be made less stringent. Thus, the
TMDL process provides for nonpoint source control tradeoffs.
(66) "Toxic Substance" means those pollutants
or combinations of pollutants, including disease-causing agents, that after
introduction to waters of the state and upon exposure, ingestion, inhalation or
assimilation either directly from the environment or indirectly by ingestion
through food chains will cause death, disease, behavioral abnormalities,
cancer, genetic mutations, physiological malfunctions (including malfunctions
in reproduction), or physical deformations in any organism or its offspring.
(67) "Wasteload Allocation" or
"WLA" means the portion of a receiving water's loading capacity allocated to
one of its existing or future point sources of pollution. WLAs constitute a
type of water quality-based effluent limitation.
(68) "Warm-Water Aquatic Life" means the
aquatic communities that are adapted to warm-water conditions and do not
contain either cold- or cool-water species.
(69) "Wastes" means sewage, industrial
wastes, and all other liquid, gaseous, solid, radioactive, or other substances
that may cause or tend to cause pollution of any water of the state.
"Water Quality Limited" means one of the
(a) A receiving stream that does
not meet narrative or numeric water quality criteria during the entire year or
defined season even after the implementation of standard technology;
(b) A receiving stream that achieves and is
expected to continue to achieve narrative or numeric water quality criteria but
uses higher than standard technology to protect beneficial uses;
(c) A receiving stream for which there is
insufficient information to determine whether water quality criteria are being
met with higher-than-standard treatment technology or a receiving stream that
would not be expected to meet water quality criteria during the entire year or
defined season without higher than standard technology.
(71) "Water Quality Swale" means a natural
depression or wide, shallow ditch used to temporarily store, route or filter
runoff for the purpose of improving water quality.
(72) "Waters of the state" means lakes, bays,
ponds, impounding reservoirs, springs, wells, rivers, streams, creeks,
estuaries, marshes, inlets, canals, the Pacific Ocean within the territorial
limits of the State of Oregon, and all other bodies of surface or underground
waters, natural or artificial, inland or coastal, fresh or salt, public or
private (except those private waters that do not combine or effect a junction
with natural surface or underground waters) that are located wholly or
partially within or bordering the state or within its jurisdiction.
(73) "Weekly (seven-day) Mean Minimum" for
dissolved oxygen means the minimum of the seven consecutive-day floating
average of the calculated daily mean dissolved oxygen concentration.
(74) "Weekly (seven-day) Minimum Mean" for
dissolved oxygen means the minimum of the seven consecutive-day floating
average of the daily minimum concentration. For application of the criteria,
this value is the reference for diurnal minimums.
(75) "Without Detrimental Changes in the
Resident Biological Community" means no loss of ecological integrity when
compared to natural conditions at an appropriate reference site or