Tue, Aug 03, 2021:On Demand
Background/Question/Methods: Environmental decision-making often requires compilation, synthesis, and interpretation of multiple kinds of data and information. One way of combining disparate data types is through a weight-of-evidence (WoE) approach. Generally, WoE consists of three steps: assemble evidence, weight evidence, and weigh the body of evidence. The US EPA recommends a WoE approach when developing numerically-based nutrient criteria and other nutrient-related water quality benchmarks that protect designated uses, including aquatic life, and would benefit from additional guidelines to improve its implementation. Such guidelines would further help states and tribes (1) maximize the use of all available evidence during the criteria development process (including evidence derived from primary and secondary sources), (2) decide which specific techniques to employ given their unique evidence, resource, and timeline constraints, and (3) further strengthen the transparency and defensibility of nutrient criteria.
Results/Conclusions: We propose additional guidelines for a robust weight-of-evidence approach in two ways. First, we explore how the WoE approach is generally appropriate for evidence types available when developing numerically-based nutrient criteria and other nutrient-related water quality benchmarks. These evidence types can include evidence derived from state water quality monitoring programs (an evidence type already consistently used) and evidence from published literature (an under-utilized evidence type). All types of evidence are capable of being weighted according to qualities of relevance, strength, and reliability, which ultimately affect how much influence a piece of evidence will have on the final conclusions. We describe applicable methods for how to combine evidence (also referred to as weighing the body of evidence), avoiding practices like vote counting that are not recommended. Visual communication of combining and interpreting evidence is highlighted. The second way we propose guidelines is through illustrative examples inspired by real states and tribes. Using knowledge of the specific evidence, resource, and timeline constraints that state and tribal regulatory agencies face in developing numeric nutrient criteria, we show that the WoE approach is adaptable to multiple situations.
Results/Conclusions: We propose additional guidelines for a robust weight-of-evidence approach in two ways. First, we explore how the WoE approach is generally appropriate for evidence types available when developing numerically-based nutrient criteria and other nutrient-related water quality benchmarks. These evidence types can include evidence derived from state water quality monitoring programs (an evidence type already consistently used) and evidence from published literature (an under-utilized evidence type). All types of evidence are capable of being weighted according to qualities of relevance, strength, and reliability, which ultimately affect how much influence a piece of evidence will have on the final conclusions. We describe applicable methods for how to combine evidence (also referred to as weighing the body of evidence), avoiding practices like vote counting that are not recommended. Visual communication of combining and interpreting evidence is highlighted. The second way we propose guidelines is through illustrative examples inspired by real states and tribes. Using knowledge of the specific evidence, resource, and timeline constraints that state and tribal regulatory agencies face in developing numeric nutrient criteria, we show that the WoE approach is adaptable to multiple situations.