Lower Nooksack River Basin Bacteria TMDL Evaluation
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Lower Nooksack River Basin Bacteria Total Maximum Daily Load Evaluation January 2000 Publication No. 00-03-006 printed on recycled paper This report is available on Ecology’s home page on the world wide web at http://www.ecy.wa.gov/biblio/0003006.html For additional copies of this publication, please contact: Department of Ecology Publications Distributions Office Address: PO Box 47600, Olympia WA 98504-7600 E-mail: [email protected] Phone: (360) 407-7472 Refer to Publication Number 00-03-006. The Department of Ecology is an equal opportunity agency and does not discriminate on the basis of race, creed, color, disability, age, religion, national origin, sex, marital status, disabled veteran's status, Vietnam Era veteran's status, or sexual orientation. If you have special accommodation needs or require this document in alternative format, please contact the Environmental Assessment Program, Joan LeTourneau at (360)-407-6764 (voice). 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Lower Nooksack River Basin Bacteria Total Maximum Daily Load Evaluation by Joe Joy Washington State Department of Ecology Environmental Assessment Program Watershed Ecology Section PO Box 47710 Olympia, Washington 98504-7710 January 2000 Waterbody Numbers: See page v Publication No. 00-03-006 printed on recycled paper This page is purposely blank for duplex printing Table of Contents Page List of Figures ....................................................................................................................iii List of Tables...................................................................................................................... iv Abstract ............................................................................................................................. v Acknowledgments.............................................................................................................. vi Executive Summary ..........................................................................................................vii Introduction ......................................................................................................................... 1 Background ................................................................................................................... 1 Problem Description...................................................................................................... 5 Project Objectives and Strategy .................................................................................... 7 Methods ............................................................................................................................. 9 TMDL Study Plan ......................................................................................................... 9 Field and Laboratory Methods ...................................................................................... 9 Data Analysis .............................................................................................................. 12 Quality Assurance and Quality Control ............................................................................ 13 Completion.................................................................................................................. 13 Replicate Sample Comparison .................................................................................... 14 Water Quality Assessment ................................................................................................ 15 Historical Data and 1997 Survey Data........................................................................ 15 Indicator Bacteria Comparisons.................................................................................. 28 Total Maximum Daily Load Analysis............................................................................... 35 Critical Conditions ...................................................................................................... 35 Setting TMDL Targets in the Nooksack River ........................................................... 36 Setting TMDL Targets for Nooksack Tributaries and Point Sources ........................ 39 Protection of Downstream Uses.................................................................................. 41 Margin of Safety.......................................................................................................... 48 TMDL Evaluation Summary....................................................................................... 48 TMDL Schedule, Actions, and Monitoring ...................................................................... 51 Schedule ...................................................................................................................... 51 Actions for Reducing Bacterial Source Impacts ......................................................... 51 Monitoring................................................................................................................... 54 References ......................................................................................................................... 57 Appendices A. Sample Site Description Locations B. Formulas and Monte Carlo Distributions C. Nooksack River Basin Dairies with NPDES Permits Page i This page is purposely blank for duplex printing Page ii List of Figures Page Figure 1. Nooksack River bacteria TMDL study area with Ecology water quality sites monitored from March 1997 to February 1998.......................................... 2 Figure 2. A trend analysis of monthly fecal coliform samples collected from the Nooksack River at Brennan (1977 - 97)........................................................... 16 Figure 3. Number of monthly fecal coliform samples collected from the Nooksack River that exceed 100 cfu/100 mL, and the cumulative annual rainfall that occurred two days prior to each sample collection .......................................... 17 Figure 4. Main stem Nooksack River fecal coliform data collected at six sites from March 1997 to February 1998 .......................................................................... 20 Figure 5. Estimated annual discharge contribution of sub-basins in the lower Nooksack River basin from March 1997 to February 1998............................. 22 Figure 6. Location and size of dairies relative to Hydrologic Group C & D soils in the lower Nooksack River basin................................................................... 24 Figure 7. Relationship between rainfall before sampling events and fecal coliform load increases in the lower Nooksack River basin ........................................... 26 Figure 8. Estimated average percentage of fecal coliform loading contributed from sub-basins to the lower Nooksack River from March 1997 to February 1998................................................................................................... 27 Figure 9. Fecal coliform data from two drogue runs on 17 June, 1997........................... 29 Figure 10. A comparison of paired fecal coliform samples that were analyzed using the most probable number and membrane filter techniques ............................ 31 Figure 11. A comparison of paired fecal coliform and E. coli sample results collected during the Nooksack River bacteria TMDL survey......................................... 32 Figure 12. Graphical demonstration of the statistical rollback method (Ott, 1995) used to calculate the fecal coliform TMDL target on the lower Nooksack River.... 37 Figure 13. Estimated percentage of fecal coliform loads from lower Nooksack sub-basins after TMDL targets are met. Load reductions are applied to 1997-1998 (Figure 8) estimates ....................................................................... 42 Figure 14. Fecal coliform samples collected from Marine Drive, Midway, and DOH Stations 12-13 during 42 survey events ................................................. 44 Figure 15. Comparison of geometric mean and 90th percentile statistics generated from DOH fecal coliform data at Station 13, and those statistics generated from the TMDL Monte Carlo simulation output. ............................................ 46 Figure 16. Monthly geometric mean and 90th percentile statistics for Stations 12 and 13 fecal coliform samples collected under pre- and post-TMDL (48% reduction) conditions.............................................................................. 47 Page iii List of Tables Page Table 1. Class AA (extraordinary) and Class A (excellent) freshwater quality standards and characteristic uses ......................................................................... 3 Table 2. Water quality limited segments in the Nooksack River basin ............................. 6 Table 3. Sampling sites for the lower Nooksack River TMDL study, 1997-98 .............. 10 Table 4. Summary of field and laboratory measurements of water, target detection limits, and methods............................................................................................ 11 Table 5. Number of visits to each Nooksack TMDL site compared to QAPP expectations ....................................................................................................... 13 Table 6. Root mean square error of the coefficient of variation for duplicate field samples collected during the Nooksack TMDL surveys .................................. 14 Table 7. A comparison of statistics between the 1997-98