Tennessee Ecoregion Delineation and Reference Site Selection Project Was Initiated in 1994
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TENNESSEE ECOREGION PROJECT 1994 - 1999 December 2000 Tennessee Department of Environment and Conservation Division of Water Pollution Control 401 Church Street Nashville TN 37243-1534 TENNESSEE ECOREGION PROJECT 1994 - 1999 December 2000 Prepared by Deborah H. Arnwine Joy I. Broach Linda K. Cartwright Gregory M. Denton Tennessee Department of Environment and Conservation Division of Water Pollution Control 401 Church Street Nashville TN 37243-1534 TABLE OF CONTENTS PAGE EXECUTIVE SUMMARY ……………………………………………………………… iv ACKNOWLEDGEMENTS ……………………………………………………………… vi CHAPTER 1 INTRODUCTION 1.1 Project Background and Funding ……………………….… 2 1.2 Project Goals and Objectives …………………………………... 3 1.20 Water Quality Criteria and Standards Development …..… 3 1.21 Biocriteria Development ………………………… 4 1.22 The Ecoregion Framework and Watersheds……………… 5 CHAPTER 2 METHODS 2.1 Delineation Process ……………………………………………... 6 2.2 Data Requirements ……………………………………………… 7 2.3 Candidate Reference Site Identification ………………………. 8 2.4 Quality Assurance/Quality Control ……………………………. 9 2.5 Habitat Assessment ……………………………………………... 11 2.50 Habitat Assessment Form …………………………………... 11 2.51 Stream Survey Form ………………………………………… 12 2.6 Macroinvertebrate Monitoring ………………………………… 12 2.60 Field Collections …………………………………………. 12 2.61 Laboratory Processing of Macroinvertebrate Samples …… 13 2.7 Water Quality Monitoring ……………………………………... 14 CHAPTER 3 RESULTS 16 3.1 Level III and Level IV Tennessee Ecoregions ………………… 16 3.2 Reference Sites ………………………………………………….. 17 3.3 Statistical Design ………………………………………………... 18 3.4 Habitat Assessment ……………………………………………... 19 3.5 Macroinvertebrate Analyses …………………………………… 29 3.6 Seasonal Variation ……………………………………………… 41 3.7 Water Quality Analyses ………………………………………… 52 3.8 Relationship of Results to Water Quality Standards …………. 52 CHAPTER 4 CONCLUSIONS ………………………………………………………… 68 CHAPTER 5 FUTURE GOALS ………………………………………………………… 70 REFERENCES ……………………………………………………………. 71 i LIST OF TABLES Table 1 Biocriteria Implementation Guidelines …………………………. 4 Table 2 Agencies Represented at Ecoregion Meetings ………………….. 7 Table 3 Field Training …………………………………………………… 9 Table 4 Habitat Assessment Parameters …………………………………. 12 Table 5 Chemical and Bacteriological Parameters ………………………. 15 Table 6 Ecoregions of Tennessee ………………………………………... 17 Table 7 Total Number of Reference Sites by Subregion ………………… 18 Table 8 Habitat Assessments by Subregion ……………………………... 21 Table 9 Preliminary Macroinvertebrate Metrics ………………………… 30 Table 10 Scoring Criteria for Tennessee Stream Condition Index (TSCI)... 32 Table 11 TSCI by Subregion………………………………………………. 33 Table 12 Macroinvertebrate Samples by Season ………………………….. 41 Table 13 Relationship Between Parameters and Water Quality Standards .. 53 Table 14 Descriptive Statistics Ecoregion 65 ……………………………... 56 Table 15 Descriptive Statistics Ecoregion 66 ……………………………... 57 Table 16 Descriptive Statistics Ecoregion 67 ……………………………... 58 Table 17 Descriptive Statistics Ecoregion 68 ……………………………... 59 Table 18 Descriptive Statistics Ecoregion 69 ……………………………... 60 Table 19 Descriptive Statistics Ecoregion 71 ……………………………... 61 Table 20 Descriptive Statistics Ecoregion 73 ……………………………... 62 Table 21 Descriptive Statistics Ecoregion 74 ……………………………... 63 LIST OF FIGURES Figure 1 Tennessee Ecoregion Map ………………………………………. 1 Figure 2 Habitat Scores of Level III Ecoregions ………………………….. 22 Figure 3 Habitat Scores for Ecoregion 65 ………………………………… 23 Figure 4 Habitat Scores for Ecoregion 66 ………………………………… 24 Figure 5 Habitat Scores for Ecoregion 67 ………………………………… 25 Figure 6 Habitat Scores for Ecoregion 68 ………………………………… 26 Figure 7 Habitat Scores for Ecoregion 71 ………………………………… 27 Figure 8 Habitat Scores for Ecoregion 74 ………………………………… 28 Figure 9 TSCI Level III Ecoregions ………………………………………. 34 Figure 10 TSCI Ecoregion 65 ……………………………………………… 35 Figure 11 TSCI Ecoregion 66 ……………………………………………… 36 Figure 12 TSCI Ecoregion 67 ……………………………………………… 37 Figure 13 TSCI Ecoregion 68 ……………………………………………… 38 Figure 14 TSCI Ecoregion 71 ……………………………………………… 39 Figure 15 TSCI Ecoregion 74 ……………………………………………… 40 Figure 16 TSCI Scores by Season, Ecoregion 65a ………………………… 42 Figure 17 TSCI Scores by Season, Ecoregion 65b ………………………… 43 Figure 18 TSCI Scores by Season, Ecoregion 65i …………………………. 44 Figure 19 TSCI Scores by Season, Ecoregion 65j …………………………. 45 Figure 20 TSCI Scores by Season, Ecoregion 66g ………………………… 46 ii Figure 21 TSCI Scores by Season, Ecoregion 67h ………………………… 47 Figure 22 TSCI Scores by Season, Ecoregion 67i …………………………. 48 Figure 23 TSCI Scores by Season, Ecoregion 68b ………………………… 49 Figure 24 TSCI Scores by Season, Ecoregion 73a ………………………… 50 Figure 25 TSCI Scores by Season, Ecoregion 74b ………………………… 51 Figure 26 Dissolved Residue Levels by Ecoregion ………………………... 64 Figure 27 Nitrate and Nitrite Levels by Ecoregion ………………………… 65 Figure 28 Copper Levels by Ecoregion ……………………………………. 66 Figure 29 Nitrate and Nitrite Levels for Ecoregion 71 …………………….. 67 Figure 30 Copper Levels for Ecoregion 71 ………………………………… 67 Appendix A Tennessee Ecoregion Characteristics Appendix B Tennessee Candidate and Final Ecoregion Reference Streams Appendix C Field Forms Appendix D Habitat Assessment Scores Appendix E Biometric Values Appendix F Water Quality Values iii EXECUTIVE SUMMARY The data obtained from the ecoregion delineation and reference site monitoring project will be used as a tool to implement the requirements of the Tennessee Water Quality Control Act. The Act requires the protection of state waters and their designated uses as defined by the Tennessee Water Quality Standards. These Standards consist of three parts. The first part defines designated uses. All waters have at least the basic four uses: fish and aquatic life, recreation, irrigation, and livestock watering and wildlife. The second part establishes the general water quality criteria needed to protect those uses. The third part is the antidegradation statement, which protects existing uses of all surface waters as established under the Act. The ecoregion and reference site framework should provide scientific, practical, and defensible background data to ensure that the Water Quality Standards fully protect and maintain the waters of the state, and their designated uses. Understanding how ecoregions affect biological health and water quality is a key step in watershed management. Reference streams serve as control streams in water quality investigations. Comparing impacted sites to ecoregion reference sites provide a tool for measuring stream quality. Monitoring impacted sites and comparing them to reference sites can also measure the progress of water quality trends within watersheds over time. To establish values that would be representative of actual background conditions, data were collected from least disturbed and minimally impacted reference streams that were representative of an ecological region referred to as an ecoregion. Obtaining these values required delineation of ecoregion boundaries and locating ecoregion reference streams. To accomplish this goal, the Tennessee Ecoregion Delineation and Reference Site Selection Project was initiated in 1994. This project was a cooperative effort between the Tennessee Department of Environment and Conservation, Division of Water Pollution Control (WPC), the USEPA Region IV, the USEPA- National Health Environmental Effects Research Laboratory (NHEERL) and Tetra Tech Inc. Project goals consisted of the following: 1. Refine Level III ecoregions and delineate Level IV ecoregions (subregions) in Tennessee. 2. Locate least impacted and minimally disturbed reference streams in each subregion. 3. Determine baseline physical, chemical, and biological conditions in reference streams. 4. Explore the use of reference data to assist in the interpretation of existing narrative criteria. Ecoregion delineation is a geographical framework that categorizes large sections of Tennessee into areas of similar geology, soils, physiography, land use, vegetation, climate, and water quality. Evaluation of background water quality and aquatic community health required establishment of ecoregion reference streams. These were streams considered minimally impacted and least disturbed, but were also representative of the subregion in which the stream flowed. Delineation of Tennessee’s Level III and Level IV ecoregions was completed in February 1997 with the generation of the EPA document Ecoregions of Tennessee (EPA/600/R-97/022). The document described in detail the typical characteristics found in each of Tennessee’s subregions. The Tennessee map illustrated eight ecoregions (Level III) and identified twenty-five subregions (Level IV). Glenn Griffith, NHEERL, provided a list of 231 potential candidate reference sites. Site evaluations required field visits to each stream. During this initial screening process, from mid- 1995 to mid-1996, additional candidate reference sites were identified resulting in a final list of 353 potential sites. During field verification, 139 sites were eliminated due to impacts. The remaining 214 sites were considered for final reference site selection. The goal was to select three reference sites per subregion. A total of 70 final reference sites was selected by August 1996. Habitat assessments, physical measurements, chemical, and biological samples were collected at the 70 final reference sites beginning in August 1996. Biological samples were collected twice per year during the low flow period (August - October) and high flow period (March-May). Chemical samples were collected on