Idaho Administrative Code › Title IDAPA 58 - Environmental Quality, Department of › Rule 58.01.02 - WATER QUALITY STANDARDS › Section 58.01.02.052 - ANTIDEGRADATION IMPLEMENTATION

Current through August 31, 2023
The antidegradation policy shall be implemented as follows:
				(3-31-22)
01.
Waters
			 Protected
. All waters receive Tier I protection. Waters receiving Tier
			 II protection will be identified using a water body by water body approach
			 during the antidegradation review. Waters given Tier III protection are
			 designated in law. (3-31-22)
02.
Restoration Projects
. Changes in water quality may be allowed by
			 the Department without an antidegradation review where determined necessary to
			 secure long-term water quality improvement through restoration projects
			 designed to trend toward natural characteristics and associated uses to a water
			 body where those characteristics and uses have been lost or diminished.
			 Restoration projects shall implement best management practices.
			 (3-31-22)
03.
General
			 Permits
. For general permits issued on or after July 1, 2011, the
			 Department will conduct an antidegradation review, including any required Tier
			 II analysis, at the time at which general permits are certified. For general
			 permits that the Department determines adequately address antidegradation,
			 review of individual applications for coverage will not be required unless it
			 is required by the general permit. For general permits that the Department
			 determines do not adequately address antidegradation, the Department may
			 conclude that other conditions, such as the submittal of additional information
			 or individual certification at the time an application is submitted for
			 coverage under a general permit, may be necessary in the general permit to
			 provide reasonable assurance of compliance with the antidegradation policy. If
			 supported by the permit record, the Department may also presume that discharges
			 authorized under a general permit are insignificant or that the pollution
			 controls required in the general permit are the least degrading alternative as
			 specified in Subsection
			 052.08.c. (3-31-22)
04.
Initiation of Antidegradation
			 Review
. Review of degradation potential and application of the
			 appropriate level of protection from degradation will be triggered by an
			 application for a new or reissued permit or license. (3-31-22)
05.
Identification of Tier II
			 Waters
. The Department will utilize a water body by water body approach
			 in determining where Tier II protection is appropriate in addition to Tier I
			 protection. This approach shall be based on an assessment of the chemical,
			 physical, biological and other information regarding the water body. The most
			 recent federally approved Integrated Report and supporting data will be used to
			 determine the appropriate level of protection as follows: (3-31-22)
a. Water bodies identified in the Integrated
			 Report as fully supporting assessed uses will be provided Tier II protection.
			 (3-31-22)
b. Water bodies
			 identified in the Integrated Report as not assessed will be provided an
			 appropriate level of protection on a case-by-case basis using information
			 available at the time of a proposal for a new or reissued permit or license.
			 (3-31-22)
c. Water bodies
			 identified in the Integrated Report as not fully supporting assessed uses will
			 receive Tier I protection for the impaired aquatic life or recreational use,
			 except as follows: (3-31-22)
i. For aquatic
			 life uses identified as impaired for dissolved oxygen, pH or temperature, if
			 biological or aquatic habitat parameters show a healthy, balanced biological
			 community is present, as described in the "Water Body Assessment Guidance"
			 published by the Idaho Department of Environmental Quality, then the water body
			 shall receive Tier II protection for aquatic life uses. (3-31-22)
ii. For recreational uses, if water quality
			 data show compliance with those levels of water quality criteria listed in
			 Sections 200,
			 210,
			 251, and
			 275 (where applicable), then the
			 water body shall receive Tier II protection for recreational uses.
			 (3-31-22)