Tier 1. Existing uses and water quality sufficient to protect those existing uses must be maintained. Categories of existing uses are the same as for designated uses
Tier 2. No activities subject to regulatory action are allowed that would cause degradation of waters that exceed fishable/swimmable quality, unless it can be shown that the lowering of water quality is necessary for important economic or social development.
Tier 3. Outstanding national resource waters are defined as high quality waters within or adjacent to national parks and wildlife refuges, state parks, wild and scenic rivers, and other designated areas of exceptional recreational or ecological significance. The quality of
outstanding national resource waters must be maintained and protected.
No discharges can lower water quality to the extent that the Texas Surface Water Quality Standards are not attained. Any discharge of wastewater that would constitute a new source or an increased source of pollution from any industrial, public, or private project or development
are required to provide a level of wastewater treatment consistent with the provisions of the
Texas Water Code and the Clean Water Act. For nonpoint sources of pollution, as necessary, cost effective and reasonable best management practices established through the Texas Water Quality Management Program are to be implemented.
Tier 1 reviews must ensure that water quality is sufficiently maintained so that existing uses are protected. All discharges that could cause an impairment of water quality are subject to Tier 1 reviews. If the existing uses and criteria of a potentially affected water body have not been previously determined, then the antidegradation review must include a preliminary determination of existing uses and criteria.
Tier 2 reviews apply to all discharges that could cause degradation of water quality where water quality exceeds levels necessary to support propagation of fish, shellfish, wildlife, and recreation in and on the water (fishable/swimmable quality). Tier 3 reviews apply to all discharges that could cause degradation of outstanding national resource waters.
Caltha LLP provides expert consulting services to public and private sector clients nationwide to address water quality standards, wastewater permitting and assessing potential impacts of chemicals in the aquatic environment.
Caltha LLP Aquatic Toxicology / WQ Standards Services Website
