A Unique Use Attainability Analysis Incorporating Collaboration and Predictive Tools

Amongst other Designated Uses, in Virginia, all waters are designated for the propagation and growth of a balanced and indigenous population of aquatic life, including game fish, that might reasonably be expected to inhabit them. A narrative or “general” criterion is applied to protect this aquatic life designated use. This criterion asserts that State waters…shall be free from substances…in concentrations…harmful to aquatic life. Historically, this criterion has been assessed through various benthic macroinvertebrate assessment guidelines.A central Appalachian headwater stream was determined to be impaired for the aquatic life use. A TMDL concluded that total dissolved solids and total suspended solids were the stressors. In the absence of approved numeric criteria for these parameters, Virginia developed ad hoc water quality targets for use in the TMDL and subsequent implementation efforts. Virginia's State law requires each TMDL to have an Implementation Plan (IP). An industrial stakeholder group believed that the default designated use was not attainable and commissioned a use attainability analysis. Furthermore, data suggested that the designated use may not have been achieved on or after November 28, 1975 (a prerequisite for a UAA).The development of this UAA has been enhanced by a unique level of cooperation amongst the various stakeholder groups. The UAA process was initiated with a demonstration that there were reasonable grounds to justify the conduct of a UAA. This reasonable grounds determination was negotiated cooperatively with several regulatory agencies and various special interest groups. As part of the cooperative agreement, this UAA was integrated with the TMDL IP. From this agreement, a UAA study plan evolved in a collaborative manner. Study oversight has been through a technical workgroup that includes both state and federal regulators.The study is using historical data to determine the level of existing use. Furthermore, relationships between the biological condition and individual stressors/pressures are being established. Remediation projects are being defined. Some of these projects will be applied in the short term. Others are proposed but may be both economically and socially infeasible. A predictive tool is being developed based upon site-specific data. This predictive tool will be used to determine the post-remediation use attainment level.Different scenarios or recommendations are expected to result from this study. For example, one possible recommendation is to retain the present designated aquatic life use and criterion. Amongst several alternative recommendations, it is conceivable that the development of a new subcategory of the use with its unique criterion could be recommended. This paper summarizes the milestones achieved to date, including the development of the predictive tool.