Current through Register Vol. 60, No. 12, December 1, 2021
Water temperatures affect the biological cycles of aquatic species and are a
critical factor in maintaining and restoring healthy salmonid populations
throughout the State. Water temperatures are influenced by solar radiation,
stream shade, ambient air temperatures, channel morphology, groundwater
inflows, and stream velocity, volume, and flow. Surface water temperatures may
also be warmed by anthropogenic activities such as discharging heated water,
changing stream width or depth, reducing stream shading, and water withdrawals.
(2) Policy. It is the policy of
the Commission to protect aquatic ecosystems from adverse warming and cooling
caused by anthropogenic activities. The Commission intends to minimize the risk
to cold-water aquatic ecosystems from anthropogenic warming, to encourage the
restoration and protection of critical aquatic habitat, and to control extremes
in temperature fluctuations due to anthropogenic activities. The Commission
recognizes that some of the State's waters will, in their natural condition,
not provide optimal thermal conditions at all places and at all times that
salmonid use occurs. Therefore, it is especially important to minimize
additional warming due to anthropogenic sources. In addition, the Commission
acknowledges that control technologies, best management practices and other
measures to reduce anthropogenic warming are evolving and that the
implementation to meet these criteria will be an iterative process. Finally,
the Commission notes that it will reconsider beneficial use designations in the
event that man-made obstructions or barriers to anadromous fish passage are
removed and may justify a change to the beneficial use for that water body.
(3) Purpose. The purpose of the
temperature criteria in this rule is to protect designated
temperature-sensitive, beneficial uses, including specific salmonid life cycle
stages in waters of the State.
Biologically Based Numeric Criteria. Unless superseded by the natural
conditions criteria described in section (8) of this rule, or by subsequently
adopted site-specific criteria approved by EPA, the temperature criteria for
State waters supporting salmonid fishes are as follows:
(a) The seven-day-average maximum temperature
of a stream identified as having salmon and steelhead spawning use on subbasin
maps and tables set out in OAR
Tables 101B, and 121B, and Figures 130B, 151B, 160B, 170B, 220B, 230B, 271B,
286B, 300B, 310B, 320B, and 340B, may not exceed 13.0 degrees Celsius (55.4
degrees Fahrenheit) at the times indicated on these maps and tables;
(b) The seven-day-average maximum temperature
of a stream identified as having core cold water habitat use on subbasin maps
set out in OAR 340-041-101 to 340-041-340: Figures 130A, 151A, 160A, 170A,
180A, 201A, 220A, 230A, 271A, 286A, 300A, 310A, 320A, and 340A, may not exceed
16.0 degrees Celsius (60.8 degrees Fahrenheit);
(c) The seven-day-average maximum temperature
of a stream identified as having salmon and trout rearing and migration use on
subbasin maps set out at OAR
Figures 130A, 151A, 160A, 170A, 220A, 230A, 271A, 286A, 300A, 310A, 320A, and
340A, may not exceed 18.0 degrees Celsius (64.4 degrees Fahrenheit);
(d) The seven-day-average maximum temperature
of a stream identified as having a migration corridor use on subbasin maps and
Tables 101B, and 121B, and Figures 151A, 170A, 300A, and 340A, may not exceed
20.0 degrees Celsius (68.0 degrees Fahrenheit). In addition, these water bodies
must have coldwater refugia that are sufficiently distributed so as to allow
salmon and steelhead migration without significant adverse effects from higher
water temperatures elsewhere in the water body. Finally, the seasonal thermal
pattern in Columbia and Snake Rivers must reflect the natural seasonal thermal
(e) The seven-day-average
maximum temperature of a stream identified as having Lahontan cutthroat trout
or redband trout use on subbasin maps and tables set out in OAR
Tables 121B, 140B, 190B, and 250B, and Figures 180A, 201A, 260A and 310A may
not exceed 20.0 degrees Celsius (68.0 degrees Fahrenheit);
(f) The seven-day-average maximum temperature
of a stream identified as having bull trout spawning and juvenile rearing use
on subbasin maps set out at OAR
Figures 130B, 151B, 160B, 170B, 180A, 201A, 260A, 310B, and 340B, may not
exceed 12.0 degrees Celsius (53.6 degrees Fahrenheit). From August 15 through
May 15, in bull trout spawning waters below Clear Creek and Mehlhorn reservoirs
on Upper Clear Creek (Pine Subbasin), below Laurance Lake on the Middle Fork
Hood River, and below Carmen reservoir on the Upper McKenzie River, there may
be no more than a 0.3 degrees Celsius (0.5 Fahrenheit) increase between the
water temperature immediately upstream of the reservoir and the water
temperature immediately downstream of the spillway when the ambient
seven-day-average maximum stream temperature is 9.0 degrees Celsius (48 degrees
Fahrenheit) or greater, and no more than a 1.0 degree Celsius (1.8 degrees
Fahrenheit) increase when the seven-day-average stream temperature is less than
9 degrees Celsius.
Unidentified Tributaries. For waters that are not identified on the "Fish Use
Designations" maps referenced in section (4) of this rule, the applicable
criteria for these waters are the same criteria as is applicable to the nearest
downstream water body depicted on the applicable map. This section (5) does not
apply to the "Salmon and Steelhead Spawning Use Designations" maps.
(6) Natural Lakes. Natural lakes may not be
warmed by more than 0.3 degrees Celsius (0.5 degrees Fahrenheit) above the
natural condition unless a greater increase would not reasonably be expected to
adversely affect fish or other aquatic life. Absent a discharge or human
modification that would reasonably be expected to increase temperature, DEQ
will presume that the ambient temperature of a natural lake is the same as its
natural thermal condition.
Oceans and Bays. Except for the Columbia River above river mile 7, ocean and
bay waters may not be warmed by more than 0.3 degrees Celsius (0.5 degrees
Fahrenheit) above the natural condition unless a greater increase would not
reasonably be expected to adversely affect fish or other aquatic life. Absent a
discharge or human modification that would reasonably be expected to increase
temperature, DEQ will presume that the ambient temperature of the ocean or bay
is the same as its natural thermal condition.
Natural Conditions Criteria. Where the
department determines that the natural thermal potential of all or a portion of
a water body exceeds the biologically-based criteria in section (4) of this
rule, the natural thermal potential temperatures supersede the
biologically-based criteria, and are deemed to be the applicable temperature
criteria for that water body.
NOTE: On August 8, 2013, the Environmental
Protection Agency disapproved rule section OAR
Consequently, section (8) is no longer effective as a water quality criterion
for purposes of CWA Section 303(c) and it cannot be used for issuing
certifications under CWA Section 401, permits under CWA Section 402, or total
maximum daily loads under CWA section 303(d).
Cool Water Species.
(a) No increase in temperature is allowed
that would reasonably be expected to impair cool water species. Waters of the
State that support cool water species are identified on subbasin tables and
figures set out in OAR
Tables 140B, 190B and 250B, and Figures 180A, 201A and 340A.
(b) See OAR
for a basin specific criterion for the Klamath River.
(10) Borax Lake Chub. State waters in the
Malheur Lake Basin supporting the Borax Lake chub may not be cooled more than
0.3 degrees Celsius (0.5 degrees Fahrenheit) below the natural condition.
Protecting Cold Water.
(a) Except as described in subsection (c) of
this rule, waters of the State that have summer seven-day-average maximum
ambient temperatures that are colder than the biologically based criteria in
section (4) of this rule, may not be warmed by more than 0.3 degrees Celsius
(0.5 degrees Fahrenheit) above the colder water ambient temperature. This
provision applies to all sources taken together at the point of maximum impact
where salmon, steelhead or bull trout are present.
A point source that discharges into or
above salmon & steelhead spawning waters that are colder than the spawning
criterion, may not cause the water temperature in the spawning reach where the
physical habitat for spawning exists during the time spawning through emergence
use occurs, to increase more than the following amounts after complete mixing
of the effluent with the river:
(A) If the
rolling 60 day average maximum ambient water temperature, between the dates of
spawning use as designated under subsection (4)(a) of this rule, is 10 to 12.8
degrees Celsius, the allowable increase is 0.5 Celsius above the 60 day
(B) If the rolling 60
day average maximum ambient water temperature, between the dates of spawning
use as designated under subsection (4)(a) of this rule, is less than 10 degrees
Celsius, the allowable increase is 1.0 Celsius above the 60 day average, unless
the source provides analysis showing that a greater increase will not
significantly impact the survival of salmon or steelhead eggs or the timing of
salmon or steelhead fry emergence from the gravels in downstream spawning
water protection narrative criteria in subsection (a) do not apply if:
(A) There are no threatened or endangered
salmonids currently inhabiting the water body;
(B) The water body has not been designated as
critical habitat; and
colder water is not necessary to ensure that downstream temperatures achieve
and maintain compliance with the applicable temperature criteria.
the Temperature Criteria.
(a) Minimum Duties.
There is no duty for anthropogenic sources to reduce heating of the waters of
the State below their natural condition. Similarly, each anthropogenic point
and nonpoint source is responsible only for controlling the thermal effects of
its own discharge or activity in accordance with its overall heat contribution.
In no case may a source cause more warming than that allowed by the human use
allowance provided in subsection (b) of this rule.
Human Use Allowance. Insignificant
additions of heat are authorized in waters that exceed the applicable
temperature criteria as follows:
(A) Prior to
the completion of a temperature TMDL or other cumulative effects analysis, no
single NPDES point source that discharges into a temperature water quality
limited water may cause the temperature of the water body to increase more than
0.3 degrees Celsius (0.5 Fahrenheit) above the applicable criteria after mixing
with either twenty five (25) percent of the stream flow, or the temperature
mixing zone, whichever is more restrictive; or
(B) Following a temperature TMDL or other
cumulative effects analysis, waste load and load allocations will restrict all
NPDES point sources and nonpoint sources to a cumulative increase of no greater
than 0.3 degrees Celsius (0.5 Fahrenheit) above the applicable criteria after
complete mixing in the water body, and at the point of maximum impact.
(C) Point sources must be in
compliance with the additional mixing zone requirements set out in OAR
(D) A point source in compliance
with the temperature conditions of its NPDES permit is deemed in compliance
with the applicable criteria.
(c) Air Temperature Exclusion. A water body
that only exceeds the criteria set out in this rule when the exceedance is
attributed to daily maximum air temperatures that exceed the 90th percentile
value of annual maximum seven-day average maximum air temperatures calculated
using at least 10 years of air temperature data, will not be listed on the
section 303(d) list of impaired waters and sources will not be considered in
violation of this rule.
Flow Conditions. An exceedance of the biologically-based numeric criteria in
section (4) of this rule, or an exceedance of the natural condition criteria in
section (8) of this rule will not be considered a permit violation during
stream flows that are less than the 7Q10 low flow condition for that water
Other Nonpoint Sources.
The department may, on a case-by-case basis, require nonpoint sources (other
than forestry and agriculture), including private hydropower facilities
regulated by a 401 water quality certification, that may contribute to warming
of State waters beyond 0.3 degrees Celsius (0.5 degrees Fahrenheit), and are
therefore designated as water-quality limited, to develop and implement a
temperature management plan to achieve compliance with applicable temperature
criteria or an applicable load allocation in a TMDL pursuant to OAR
(A) Each plan must ensure that the nonpoint
source controls its heat load contribution to water temperatures such that the
water body experiences no more than a 0.3 degrees Celsius (0.5 degree
Fahrenheit) increase above the applicable criteria from all sources taken
together at the maximum point of impact.
(B) Each plan must include a description of
best management practices, measures, effluent trading, and control technologies
(including eliminating the heat impact on the stream) that the nonpoint source
intends to use to reduce its temperature effect, a monitoring plan, and a
compliance schedule for undertaking each measure.
(C) The Department may periodically require a
nonpoint source to revise its temperature management plan to ensure that all
practical steps have been taken to mitigate or eliminate the temperature effect
of the source on the water body.
(f) Compliance Methods. Anthropogenic sources
may engage in thermal water quality trading in whole or in part to offset its
temperature discharge, so long as the trade results in at least a net thermal
loading decrease in anthropogenic warming of the water body, and does not
adversely affect a threatened or endangered species. Sources may also achieve
compliance, in whole or in part, by flow augmentation, hyporheic exchange
flows, outfall relocation, or other measures that reduce the temperature
increase caused by the discharge.
(g) Release of Stored Water. Stored cold
water may be released from reservoirs to cool downstream waters in order to
achieve compliance with the applicable numeric criteria. However, there can be
no significant adverse impact to downstream designated beneficial uses as a
result of the releases of this cold water, and the release may not contribute
to violations of other water quality criteria. Where the Department determines
that the release of cold water is resulting in a significant adverse impact,
the Department may require the elimination or mitigation of the adverse impact.
Criteria. The Department may establish, by separate rulemaking, alternative
site-specific criteria for all or a portion of a water body that fully protects
the designated use.
(a) These site-specific
criteria may be set on a seasonal basis as appropriate.
The Department may use, but is not
limited by the following considerations when calculating site-specific
(A) Stream flow;
(B) Riparian vegetation potential;
(C) Channel morphology modifications;
(D) Cold water tributaries and
(E) Natural physical
features and geology influencing stream temperatures; and
(F) Other relevant technical data.
(c) DEQ may consider the thermal
benefit of increased flow when calculating the site-specific criteria.
(d) Once established and approved
by EPA, the site-specific criteria will be the applicable criteria for the
water bodies affected.