A comparison of three visual assessments for riparian and stream health

Visual assessments are integral components of several widely promoted efforts to assess the health of stream and riparian areas across the Nation. The U.S. Environmental Protection Agency's (EPA) Habitat Assessment Field Data Sheet (HAFDS), U.S. Department of Agriculture's Natural Resources Conservation Service's (NRCS) Stream Visual Assessment (SVA), and U.S. Department of Interior (USDI) Bureau of Land Management's (BLM) Proper Functioning Condition (PFC) assessment were applied to 234 rangeland riparian areas to determine: 1) how well the assessments correlate, and 2) how site-specific stream and riparian characteristics affect the outcome of each assessment and thus the comparison of outcomes across stream types. Habitat Assessment Field Data Sheet and Stream Visual Assessment are habitat driven assessments, which target similar parameters resulting in a strong positive correlation between these methods (r = 0.81). BLM's Proper Functioning Condition focuses on parameters related to hydrologic function, thus a weaker correlation was found when comparing Proper Functioning Condition to the Habitat Assessment Field Data Sheet and the NRCS' Stream Visual Assessment methods (r = 0.58 and 0.54, respectively). A combination of one habitat assessment and Proper Functioning Condition should be utilized to conduct a comprehensive assessment of riparian/stream health. Site characteristics, which were significantly associated with assessment outcomes included entrenchment ratio, substrate size, channel width to depth and slope. This presents a problem in that comparison of assessment outcomes across different streams and stream reaches are confounded by factors such as slope and substrate type, which may not always be indicative of riparian/stream health. The Rosgen Stream Morphology Classification system was used to successfully control for the effect of these site-specific effects on assessment outcome, allowing for comparison of riparian/stream health assessments across streams.