CSS supported the establishment of biologically-based criteria to protect and maintain self-sustaining populations of native, sediment-sensitive aquatic species for EPA's Western Ecology Division. We developed sediment indices for fish and macroinvertebrates in mountain regions of the western U.S., using Environmental Monitoring and Assessment Program (EMAP) databases which include probability-based survey data for aquatic vertebrates, macroinvertebrates, periphyton, chemistry, and physical habitat for several thousand wadeable stream reaches throughout the nation. CSS used these data to explore approaches for developing regionally-specific indices of habitat quality based on the observed distribution and relative abundance of fish, amphibians, and macroinvertebrates. We developed an approach for analyzing sediment and biological data and synthesizing related information to derive biologically-based sediment criteria. We started by examining the empirical relationships between indices of biotic integrity (IBI) for aquatic vertebrates and macroinvertebrates with measures of percent areal streambed fines (≤ 0.06 mm) and sand and fines (≤ 2 mm). We used quantile regression analyses to model the aquatic vertebrate and macroinvertebrate IBIs and species specific responses to both particle size classes. The models predicted taxa response with increasing percent areal sediment in both particle size classes. Additional analyses produced biologically-based sediment criteria that define thresholds beyond which sensitive assemblages or species experience harmful effects from excess sediment. The results of this research have been published in peer-reviewed journals.
From 2006 through 2009, Dynamac provided technical support to EMAP's Stream Habitat Quality Indices Project. Federal and state agencies have a need for biologically-based habitat criteria to set regional sediment criteria that protect and maintain self-sustaining populations of native, sediment-sensitive aquatic species.