Evaluating riparian health assessment methods for perennial streams in Montana

Abstract

The purpose of this study was to evaluate current riparian assessment protocols and to determine if they reflect ecosystem function and/or water quality across large spatial scales, and are they congruent in their assessment of stream health. Objectives for this study include: 1) to compare three riparian assessment protocols in their agreement of evaluation of stream health, 2) to compare each protocol and a bank stability measure (Greenline) to a measure of aquatic macroinvertebrate diversity and richness, 3) to compare how well these protocols reflect water quality and instream conditions on perennial streams located in western and eastern Montana, and 4) determine how sensitive the protocols are to different geological provinces and water source. Five streams were located in western Montana where the water originated from high elevation snow pack. Five more streams were measured in eastern Montana with water originating from prairie springs. Aquatic macroinvertebrates and environmental parameters were measured along four reaches on each stream. All aquatic macroinvertebrates were keyed to family, and orders Ephemeroptera-Plecoptera-Trichoptera (EPT) were keyed to genera. Three lotic assessment protocols (Proper Functioning Condition (PFC), Riparian Assessment for Lotic systems (NRCS) and Stream Visual Assessment Protocol (SVAP)) were used at each of the reaches measured to assess riparian health. Following data analysis the Stream Visual Assessment Protocol (SVAP) was the only method that had a significant correlation with geological province and aquatic biotic integrity. The SVAP assessment could distinguish differences between western and eastern geological provinces (P < 0.01), reflected EPT diversity (R2 = 0.75), EPT richness (R2 = 0.87), and water quality (R2 = 0.80) better than the other methods. However, the PFC and NRCS assessment protocols were the most similar in stream health ratings (kappa = 0.52). Overall the SVAP most accurately reflected instream conditions across Montana. Only the SVAP reflected taxonomic distributions with a correlation coefficient > 0.90. Substrate composition, discharge (CFS), elevation, average annual precipitation, water quality, and glide habitat types were correlated (¡Ý 0.70) with macroinvertebrate taxonomic distribution and composition. Results of this study suggest that SVAP should be used when management goals are focused on perennial streams and whether or not those streams can support a particular fishery in Montana.