2005–2006 Assessment of Fish and Macroinvertebrate Communities of the Tualatin River Basin, Oregon
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FINAL REPORT 2005–2006 ASSESSMENT OF FISH AND MACROINVERTEBRATE COMMUNITIES OF THE TUALATIN RIVER BASIN, OREGON MICHAEL B. COLE JENA L. LEMKE CHRISTOPHER R. CURRENS PREPARED FOR CLEAN WATER SERVICES HILLSBORO, OREGON PREPARED BY ABR, INC.–ENVIRONMENTAL RESEARCH & SERVICES FOREST GROVE, OREGON 2005-2006 ASSESSMENT OF FISH AND MACROINVERTEBRATE COMMUNITIES OF THE TUALATIN RIVER BASIN, OREGON FINAL REPORT Prepared for Clean Water Services 2550 SW Hillsboro Highway Hillsboro, OR 97123-9379 By Michael B. Cole, Jena L. Lemke, and Christopher Currens ABR, Inc.--Environmental Research and Services P.O. Box 249 Forest Grove, OR 97116 August 2006 Printed on recycled paper. EXECUTIVE SUMMARY RIVPACS O/E scores from high-gradient reaches ranged from 0.24 to 1.05 and averaged • Biological monitoring with fish and 0.72, while multimetric scores ranged from 11 macroinvertebrate communities is widely used to 46 and averaged 27.9. The two approaches to determine the ecological integrity of surface produced similar impairment-class groupings, waters. Such surveys directly assess the status as almost half of the high-gradient-reach of surface waters relative to the primary goal macroinvertebrate communities that scored as of the Clean Water Act and provide unimpaired according to O/E scores also information valuable to water quality planning received unimpaired multimetric scores. and management. As such, fish and Upper Gales Creek received both the highest macroinvertebrate communities are O/E and multimetric scores of 1.05 and 46, periodically assessed by Clean Water Services respectively. Three sites received “fair” O/E to assist with water quality management in the scores ranging from 0.779 to 0.877. These Tualatin River basin. Fish and sites scored as slightly or moderately impaired macroinvertebrate communities, physical according to multimetric scores. Fourteen habitat, and water chemistry were sampled in high-gradient reaches received “poor” O/E streams throughout the Tualatin River basin in scores; five of these sites also received fall 2005 to determine current ecological severely impaired multimetric scores. These conditions of streams within the watershed. most impaired streams occurred in areas with Fish communities were sampled again in higher urban and agricultural land use spring 2006 to examine seasonal changes in intensities. Multimetric scores and O/E scores fish community conditions. Sampling sites were significantly correlated with a number of were selected to correspond with sites sampled environmental variables, including percent in previous fish and macroinvertebrate surveys urban land use, percent forested land use, performed between 1999 and 2001. In fall effective impervious area, percent total urban 2005, fish communities were assessed in 64 and agricultural land use, water temperature, stream reaches, while macroinvertebrate conductivity, and dissolved oxygen, and communities were assessed in 63 reaches. several measures of streambed substrate Fish and macroinvertebrate sampling occurred conditions. Although significant, these in the same reach at 29 locations. relationships are only correlative and do not • Depending on stream type and habitat establish cause-and-effect relationships sampled, macroinvertebrate data were between environmental conditions and analyzed either with both multimetric analysis instream biological conditions. and predictive models known as RIVPACS • Across all high-gradient reaches, models (in the case of high-gradient streams macroinvertebrate community conditions were from which riffles were sampled) or with only similar to those reported in 2001 (Cole 2002). the RIVPACS model (in the case of Reaches sampled in both years (n = 24) low-gradient streams from which glides were averaged multimetric scores of 28.9 in 2005 sampled). Fish community data were analyzed compared to 27.7 in 2001. A two-sample with the Index of Biotic Integrity (IBI) paired t-test performed to examine the data for developed by the USEPA and modified by a change in average conditions between the ODFW for use in Tualatin River basin streams. two years was not significant (p = 0.502). Scoring systems of these three approaches occur on different scales, but in all cases higher • Biological integrity of macroinvertebrate scores represent higher ecological integrity. communities varied less among low-gradient reaches and generally scored lower than in • Macroinvertebrate community conditions high-gradient reaches. Four reaches selected ranged widely among high-gradient stream as representing least-impaired low-gradient reaches as indicated by both RIVPACS O/E conditions in the Tualatin River basin received scores and DEQ multimetric scores. O/E scores ranging from 0.340 to 0.726. The i 2005–2006 Tualatin Streams Assessment mean of these four scores (0.557) was used as generated from the 2001 ODFW study and the the threshold for determining impairment of current study were similar, with IBI-score low-gradient reaches. Based on this differences of less than 10 points. Statistically benchmark, only one of 36 sample reaches significant correlations occurred between IBI (excluding the reference reaches), the lower scores and five measured environmental East Fork of Dairy Creek, was classified as variables, including percent riffle habitat, unimpaired with an O/E score of 0.574. The morning dissolved oxygen concentrations, remaining 35 O/E scores calculated from percent sand and fines, afternoon water low-gradient reaches ranged from 0.143 to temperature, and conductivity (p < 0.0001; 0.469. These communities generally exhibited Figure 8). a low taxa richness, few or no EPT taxa, high • Collectively, our results suggest that biological dominance by one or a few tolerant taxa, and a conditions largely remain the same as those high community-wide tolerance to measured between 1999 and 2001, with disturbance. O/E scores calculated from exceptions as noted in this report. As these low-gradient reaches were negatively periodic monitoring efforts continue into the correlated with percent embeddedness and future, longer-term data sets should reveal positively correlated with dissolved oxygen trends in these conditions in relation to land concentrations. Physical characteristics of use changes, water resource management low-gradient streams on the Tualatin Valley programs, and restoration activities occurring floor differ from those of higher-gradient in the Tualatin River basin. streams located in areas of more topographic relief within the basin. Naturally occurring dominance by sand and silt substrates and slower water velocities would naturally yield different macroinvertebrate communities on valley floor streams. Because the RIVPACS model and DEQ multimetric scoring system have not yet been calibrated for use with such Tualatin Valley floor streams, we caution the use of these results from low-gradient streams for regulatory purposes, as current tools do not provide reliable separation of naturally occurring differences (between macroinvertebrate communities occurring in high and low-gradient streams) from changes produced by anthropogenic alteration of instream conditions. • A total of 112 fish-community IBI scores were calculated from reaches surveyed during fall, 2005 and spring, 2006. The upper Tualatin River reach was the only site to score as in acceptable condition in each season. Most reaches received IBI scores less than 50 and corresponding severely impaired classifications. Approximately 30% of reaches received IBI scores from 51 to 74 and resulting marginally impaired designations. Changes in IBI scores from fall to spring were generally modest. Approximately half of the IBI scores 2005–2006 Tualatin Streams Assessment ii TABLE OF CONTENTS EXECUTIVE SUMMARY ...........................................................................................................................i LIST OF FIGURES ......................................................................................................................................iii LIST OF TABLES........................................................................................................................................iv LIST OF APPENDICES................................................................................................................................ v ACKNOWLEDGMENTS ............................................................................................................................. v INTRODUCTION ......................................................................................................................................... 1 STUDY AREA .............................................................................................................................................. 1 METHODS.................................................................................................................................................... 1 SAMPLE SITE SELECTION AND OVERALL SAMPLING DESIGN .................................................. 1 HABITAT ASSESSMENTS ...................................................................................................................... 4 HABITAT UNITS SURVEY................................................................................................................... 4 CROSS SECTION SURVEYS ................................................................................................................ 7 RIPARIAN SURVEYS.........................................................................................................................