Quantifying regional reference conditions for freshwater ecosystem management: A comparison of approaches and future research needs

Accurate and robust approaches for quantifying regional reference conditions are critical to the management and restoration of freshwater resources. We considered approaches developed for streams, lakes, or wetlands and for either biological or chemical waterbody features to review 4 common approaches for quantifying regional reference conditions: multimetric, multivariate, landscape-context statistical modeling, and paleolimnology. We focused on the major steps in the decision-making process that led to the most appropriate approach. Based on this synthesis, we argue that there is a need to (1) more explicitly quantify the spatial scale of waterbody variation within and across regions, (2) develop and use predictive classification models in a more explicit fashion to more effectively model this local and regional variation, (3) consider additional metrics with a focus on lakes and wetland responses to both individual and multiple anthropogenic stressors, and (4) continue to develop quantitative approaches to explicitly account for uncertainties in regional reference condition predictions.