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Tiered Aquatic Life Use Model

Tiered Aquatic Life Use Model. Christy Pickens, Physical Research Scientist Water Quality Control Division Colorado Dept. of Public Health and Environment 30 July 2003. Purpose of Model.

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Tiered Aquatic Life Use Model

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  1. Tiered Aquatic Life Use Model Christy Pickens, Physical Research Scientist Water Quality Control Division Colorado Dept. of Public Health and Environment 30 July 2003

  2. Purpose of Model • The tiered aquatic life use framework is a conceptual model predicting the response of aquatic communities to increasing human disturbance. • The conceptual model is a draft framework for using biological assessment information to refine designated aquatic life uses. www.brainybetty.com

  3. Purpose of Model EPA developed the TALU model for a nationally consistent approach. • Scientifically defensible benchmarks • Common framework for communication and evaluation- public, stakeholders, across political boundaries • Protection for excellent quality waters • Achievable goals for incremental restoration www.brainybetty.com

  4. Purpose of Model National ALUS Workgroup • Biological Condition Gradient (BCG) focus of workgroup in 2001. • Human Disturbance Gradient (HDG) focus of workgroup in 2002. • Workgroup recommendations going forward to EPA this spring with the conceptual models, implementation options, case examples. www.brainybetty.com

  5. TALU Model Basics Bioassessments help states develop expectations for acceptable biological conditions. This is accomplished through the technical process of developing aquatic life goals, aquatic life uses (ALUs). Biological assessments allow various levels of ALUs. Using several types, or tiers, of ALUs allows states and tribes to allocate limited resources to waterbodies in proportion to their need for protection. www.brainybetty.com

  6. ALUS Integrity ALUS is determined by assessing: • Response variable (biological condition) to determine impairments and full support • Stressors (physical and chemical conditions) to determine impairment www.brainybetty.com

  7. TALU Conceptual Model www.brainybetty.com

  8. TALU Model Basics The tiered system of use designations provides for different levels of protection and reflects the choices implicit in reconciling the “ideal” (represented by least impacted reference conditions) with the “reality”, the ongoing effects of two centuries of intensive human use of the state’s land and water resources. www.brainybetty.com

  9. TALU Model Basics Key Points to Emphasize: • Framework is conceptual • Number of tiers to be determined by State • “Best Fit” approach recommended • The framework may be quantitatively defined by many possible methods • BCG is a quality gradient, not a classification www.brainybetty.com

  10. TALU Model Basics • Human Disturbance Gradient (HDG) • Biological Condition Gradient (BCG) www.brainybetty.com

  11. TALU Model Basics www.brainybetty.com

  12. TALU Model Basics www.brainybetty.com

  13. TALU Model Basics Human Disturbance Gradient www.brainybetty.com

  14. TALU Model BasicsHDG Layout Six tiers (A-F) Six major stressor classes • Habitat Structure • Flow Regime • Water Quality • Toxics and Bioengineered Chemicals • Energy Sources • Biotic Interactions www.brainybetty.com

  15. TALU Model BasicsHDG Layout Six major disturbance classes • Landscape Character • Riparian Condition • Barriers • Channel Morphology (map scale) • Atmospheric Deposition • Biotic Interactions www.brainybetty.com

  16. TALU Model BasicsHDG Rationale • Essential for determining reference sites and minimal disturbance • Necessary for metric and index development and evaluation • Often represents half the variability in biological response scores • Easier to assess than large suite of stressors • Assists in diagnosing stressors • Source of most manageable stressors • Critical for stream protection, BMPs and restoration www.brainybetty.com

  17. TALU Model Basics Draft Model Tiers – 6 levels • Natural structure and function of biotic community maintained • Minimal changes in structure and function • Evident changes in structure and minimal changes in function • Moderate changes in structure and minimal changes in function • Major changes in structure and moderate changes in function • Severe changes in structure and function www.brainybetty.com

  18. TALU Conceptual Model www.brainybetty.com

  19. TALU Conceptual Model www.brainybetty.com

  20. HDG Concepts Human disturbance gradient does not necessarily imply degradation. Human disturbance gradient addresses two basic questions: What is the departure from expected condition as a result from human activities? What is the impact of this departure from expected condition on the biotic community? www.brainybetty.com

  21. TALU Model Basics Biological Condition Gradient www.brainybetty.com

  22. TALU Model Basics www.brainybetty.com

  23. TALU Model Basics Biological Condition Gradient (BCG) BCG is a quality gradient, with the upper end of the scale reflecting “natural conditions” corresponding with the CWA integrity objective. BCG is not a model to be used for classification of natural systems, such as ecoregions. BCG would only be applied once they have been appropriately classified. BCG provides consistency among states using different approaches. www.brainybetty.com

  24. TALU Model Basics Biological Condition Gradient (BCG) The first tier of the model characterizes the natural expectations for a waterbody unimpacted or minimally impacted by human activities. The subsequent tiers show the response of the biological community to increasing human disturbance. www.brainybetty.com

  25. TALU Model Basics BCG Layout 10 Major Attributes • Taxonomic composition and tolerance • Attributes I-V • Regionally Endemic through Tolerant • Non-Native taxa • Attribute VI • Organism condition • Attribute VII • Ecosystem function • Attribute VI • Physical-biotic interactions • Attributes IX-X www.brainybetty.com

  26. BCG Attributes www.brainybetty.com

  27. BCG Attributes www.brainybetty.com

  28. BCG Attributes www.brainybetty.com

  29. BCG Attributes www.brainybetty.com

  30. BCG Attributes www.brainybetty.com

  31. BCG Attributes www.brainybetty.com

  32. BCG Attributes EX www.brainybetty.com

  33. ALUS Tiers Provide Consistency 1 2 3 4 5 6 a b c d e f Natural Degraded Susan P. Davies, MDEP

  34. TALU Model Thinking ahead… How can we transition from describing what we see to establishing thresholds? www.brainybetty.com

  35. Designated Aquatic Life Uses in Vermont natural/ minimallyaltered 1 Class A1: Excellent - Biota within the range of the natural condition Threshold criterion A1 2 Class B1: Very Good - Minor changes to structure and function; tolerant/intolerant forms within the range of reference condition. Biological Condition Threshold criterion B1 Class B2/3: Good - Moderate changes in the relative proportions of tolerant, intolerant, taxonomic and functional components. 3 Threshold criterion B2/3 Biocondition Gradient Tiers 4 5 Non-Support: Fair-Very Poor highly altered Not meeting CWA 101a uses for protection & propagation of aquatic life 6 Human Disturbance High Low

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