Rhode Island Code of Regulations › Title 250 - Department of Environmental Management › Chapter 150 - Water Resources › Subchapter 05 - Water Quality › Part 1 - Water Quality Regulations › Section 250-RICR-150-05-1.20 - Antidegradation of Water Quality Standards

Current through June 14, 2024
A. Purpose - The
				  State Antidegradation Regulations are based on the federal Antidegradation
				  Policy requirements, Antidegradation Policy and Implementation Methods,
				  40 C.F.R. §
											131.12 and have as their objective the
				  maintenance and protection of various levels of surface water quality and uses.
				  Antidegradation applies to all projects or activities subject to these
				  regulations which will likely lower water quality or affect existing or
				  designated water uses, including but not limited to all Water Quality
				  Certification reviews and any new or modified RIPDES permits. For the disposal
				  of dredged or fill material into the waters of the State, Guidelines for
				  Specification of Disposal Sites for Dredged or Fill Material, 40 C.F.R. §
				  404(b)(1), incorporated above in §
										1.3(C) of
				  this Part, guidelines shall be followed in the evaluation of
				  40 C.F.R. §
											131.12(a)(1), incorporated
				  above in §
										1.3(F) of
				  this Part, and the State's Antidegradation Policy. The Antidegradation
				  regulations consist of four (4) tiers of water quality protection.
B. Tier 1 - Protection of Existing Uses - Any
				  existing in situ water uses and level of surface water quality necessary to
				  protect the existing uses, shall be maintained and protected.
C. Tier 2 - Protection of Water Quality in
				  High Quality Waters - With the exception of Outstanding National Resource
				  Waters, in surface waters where the existing water quality exceeds levels
				  necessary to support propagation of fish and wildlife and recreation in and on
				  the water, that quality shall be maintained and protected, except for
				  insignificant changes in water quality as determined by the Director and in
				  accordance with §
										1.27 of this Part. An
				  exception to this level of protection may only be allowed if it can be proven
				  to the Director by a preponderance of clear and scientifically valid evidence
				  having a probative value, and the Director finds, after full satisfaction of
				  the intergovernmental coordination and public participation provisions of the
				  RI Continuing Planning Process, that allowing significant water quality
				  degradation is necessary to accommodate important economic and social benefit
				  in the area in which the receiving waters are located. In allowing such
				  significant degradation or lower water quality, the Director shall assure water
				  quality adequate to fully protect existing and designated uses. In allowing a
				  change in water quality, significant or insignificant, all reasonable measures
				  to minimize the change shall be implemented. Adequate scientifically valid
				  documentation shall be provided to the Director demonstrating that designated
				  and existing uses, water quality to protect those uses, and all applicable
				  water quality standards, will be fully protected. Further, the highest
				  statutory and regulating requirements for all new and existing point sources
				  and all cost-effective and reasonable best management practices for nonpoint
				  source control shall apply.
D. Tier
				  21/2 - Protection of Water Quality for SRPWs - Where high quality waters
				  constitute a SRPW, there shall be no measurable degradation of the existing
				  water quality necessary to protect the characteristic(s) which cause the
				  waterbody to be designated as an SRPW. Notwithstanding that all public drinking
				  water supplies are SRPWs, public drinking water suppliers may undertake
				  temporary and short term activities within the boundary perimeter of a public
				  drinking water supply impoundment for essential maintenance or to address
				  emergency conditions in order to prevent adverse effects on public health or
				  safety, provided that these activities comply with the requirements set forth
				  in §
										1.20(B) of
				  this Part (Tier 1 Protection of Existing Uses) and §
										1.20(C) of
				  this Part (Tier 2 Protection of Water Quality in High Quality
				  Waters).
E. Tier 3 - Protection of
				  Water Quality for ONRWs - Where high quality waters constitute an Outstanding
				  National Resource, as defined in §
										1.7 of this Part, that water
				  quality shall be maintained and protected. The State may allow some limited
				  activities that result in temporary and short-term changes in the water quality
				  of an ONRW. Such activities must not permanently degrade water quality or
				  result in water quality lower than that necessary to protect the existing uses
				  in the ONRW.
F. Implementation -
				  The Antidegradation provisions shall be implemented in accordance with the
				  Antidegradation Implementation Policy §
										1.27 of this
				  Part.