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Region 6 Biological Integrity Project Information

The Louisiana Department of Environmental Quality (LDEQ) has adopted narrative biological criteria and characterized aquatic communities inhabiting wadeable reference streams in non-tidal regions of the state. They have developed multi metric indices for fish and macroinvertebrates for wadeable streams for some ecoregions (Dewalt 1995). LDEQ has also evaluated a waterbody classification system, based on channel geomorphology and hydrology characteristics, that has the potential to refine their ecoregion based classification system (Smythe-Genovese 2001).

The proposed study will focus on the application and refinement of the existing indices and stream classification system with emphasis on the relationship between selected water quality variables and biological integrity. The study will facilitate the refinement of water quality standards use designations and supporting criteria, and advance LDEQ's ability to assess biological integrity, addressing two primary recommendations made by the National Academy of Sciences (NAS 2001).

Objective 1: Identify the most important factors that must be integrated into a waterbody classification system and identify the number of classes that are needed to minimize natural variability in measurable aquatic community attributes that represent the composition, diversity, and function of communities inhabiting undisturbed or least disturbed streams and rivers within the study area.

Objective 2: Estimate the percentage of streams and rivers within the study area that support a level of biological integrity comparable to appropriate reference waters, as described in the Louisiana water quality standards.

Objective 3: Characterize the typical concentrations and range of variability, during times when waterbodies are unaffected by runoff, of water quality constituents and dissolved oxygen minima observed in least disturbed streams and rivers supporting biological integrity. Identify the concentrations of water quality variables that are associated with a loss of biological integrity in waters affected by land use.

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