Stream Quality Index calibration/validation data for southern California

Assessment of stream health is a function of the physical, chemical, and biological integrity of the water body. While monitoring of all three indicator types is common, combining them into a unified assessment of stream quality is rare. In this study, a unified index was developed that compares biological response to physical and chemical stressors for southern California wadeable streams using a scientifically rigorous, easy-to-understand tool intended to facilitate stream management. The Stream Quality Index (SQI) is based on a stressor-response empirical model that quantifies the expected likelihood that chemical and physical stressors will impact multiple components of biological condition. While the individual stressor and response components are quantitative and have similar meaning across a variety of environmental settings, the final SQI narrative assessment is categorical and designed to be directly actionable within a management context. The four narrative assessment categories are: (1) “healthy and unstressed” (i.e., unimpacted biology, no stressors); (2) “healthy and resilient” (i.e., stressed, but biological communities are healthy); (3) “impacted and stressed” (i.e., impacted biology from observed stressors); and (4) “impacted by unknown stress” (i.e., biology is impacted, but stressors are low). To facilitate adoption by managers, a web-based application was developed that not only maps overall SQI results, but also enables users to readily access underlying quantitative information for stressors and biological responses. This transparent design was intended; high-level output and foundational components of the SQI are relevant for different audiences and details are not sacrificed for accessibility. The dataset provided herein is the calibration and validation data used to create the SQI.