Fecal Coliform TMDL For Tuscumbia River Canal North Independent Basin, Alcorn and Prentiss Counties, Mississippi May 19, 2000 Prepared By Mississippi Department of Environmental Quality Office of Pollution Control TMDL/WLA Section/Water Quality Assessment Branch MDEQ PO Box 10385 Jackson, MS 39289-0385 (601) 961-5171 ___________________________________________Fecal Coliform TMDL for Tuscumbia River Canal FOREWORD This report has been prepared in accordance with the schedule contained within the federal consent decree dated December 22, 1998. The report contains one or more Total Maximum Daily Loads (TMDLs) for waterbody segments found on Mississippi’s 1996 Section 303(d) List of Impaired Waterbodies. Because of the accelerated schedule required by the consent decree, many of these TMDLs have been prepared out of sequence with the State’s rotating basin approach. The segments addressed are comprised of monitored segments that have data indicating impairment. The implementation of the TMDLs contained herein will be prioritized within Mississippi’s rotating basin approach. The amount and quality of the data on which this report is based are limited. As additional information becomes available, the TMDLs may be updated. Such additional information may include water quality and quantity data, changes in pollutant loadings, or changes in landuse within the watershed. In some cases, additional water quality data may indicate that no impairment exists. ___________________________________________________________________________ii ___________________________________________Fecal Coliform TMDL for Tuscumbia River Canal CONTENTS Page FOREWORD.............................................................................................................................. ii MONITORED SEGMENT IDENTIFICATION ......................................................................... v EXECUTIVE SUMMARY........................................................................................................ vi 1.0 INTRODUCTION ............................................................................................................1-1 1.1 Background...........................................................................................................1-1 1.2 Applicable Waterbody Segment Use ......................................................................1-3 1.3 Applicable Waterbody Segment Standard...............................................................1-4 2.0 TMDL ENDPOINT AND WATER QUALITY ASSESSMENT.......................................2-1 2.1 Selection of a TMDL Endpoint and Critical Condition ...........................................2-1 2.2 Discussion of Instream Water Quality ....................................................................2-1 2.2.1 Inventory of Available Water Quality Monitoring Data............................2-1 2.2.2 Analysis of Instream Water Quality Monitoring Data...............................2-2 3.0 SOURCE ASSESSMENT.................................................................................................3-1 3.1 Assessment of Point Sources .................................................................................3-1 3.2 Assessment of Nonpoint Sources ...........................................................................3-2 3.2.1 Failing Septic Systems..............................................................................3-4 3.2.2 Wildlife ....................................................................................................3-4 3.2.3 Land Application of Hog and Cattle Manure.............................................3-4 3.2.4 Grazing Beef and Dairy Cattle..................................................................3-5 3.2.5 Land Application of Poultry Litter............................................................3-5 3.2.6 Cattle Contributions Deposited Directly Instream .....................................3-5 3.2.7 Urban Development .................................................................................3-5 4.0 MODELING PROCEDURE: LINKING THE SOURCES TO THE ENDPOINT .............4-1 4.1 Modeling Framework Selection .............................................................................4-1 4.2 Model Setup..........................................................................................................4-1 4.3 Source Representation ...........................................................................................4-1 4.3.1 Failing Septic Systems..............................................................................4-2 4.3.2 Wildlife ....................................................................................................4-2 4.3.3 Land Application of Hog and Cattle Manure.............................................4-2 4.3.4 Grazing Beef and Dairy Cattle..................................................................4-3 4.3.5 Land Application of Poultry Litter............................................................4-3 4.3.6 Cattle Contributions Deposited Directly Instream .....................................4-3 4.3.7 Urban Development .................................................................................4-3 4.4 Stream Characteristics ...........................................................................................4-4 4.5 Selection of Representative Modeling Period .........................................................4-4 4.6 Model Calibration Process .....................................................................................4-5 4.7 Existing Loading....................................................................................................4-5 ___________________________________________________________________________iii ___________________________________________Fecal Coliform TMDL for Tuscumbia River Canal 5.0 ALLOCATION.................................................................................................................5-1 5.1 Wasteload Allocations ...........................................................................................5-1 5.2 Load Allocations....................................................................................................5-1 5.3 Incorporation of a Margin of Safety .......................................................................5-3 5.4 Calculation of the TMDL.......................................................................................5-3 5.5 Seasonality ............................................................................................................5-4 6.0 CONCLUSION.................................................................................................................6-1 6.1 Future Monitoring ................................................................................................6-1 6.2 Public Participation................................................................................................6-1 DEFINITIONS .......................................................................................................................D-1 ABBREVIATIONS ................................................................................................................A-1 REFERENCES....................................................................................................................... R-1 APPENDIX A ..................................................................................................................... AA-1 FIGURES Page 1.1a.... Tuscumbia River Canal Impaired Segment....................................................................1-2 1.1b ... Tuscumbia River Canal Subwatersheds.........................................................................1-3 3.2 ..... Landuse Distribution.....................................................................................................3-3 TABLES Page 1.1 ..... Land Distribution in Acres for the Tuscumbia River Canal Watershed...........................1-1 2.2a.... Fecal Coliform Data reported in the Tuscumbia River Canal, Station 07029310 ............2-2 2.2b ... Statistical Summaries for Station 07029310 ..................................................................2-2 3.1 ..... Inventory of Point Source Dischargers..........................................................................3-1 3.2 ..... Landuse Distribution in Number of Acres .....................................................................3-3 4.3 ..... Urban Landuse Distribution ..........................................................................................4-4 5.1 ..... Wasteload Allocations ..................................................................................................5-1 5.2a.... Fecal Coliform Loading Rates for Nonpoint Source Cattle Access to Streams...............5-2 5.2b ... Fecal Coliform Loading Rates for Failing Septic Tanks (50% WLA and 50% LA) ........5-2 5.4 ..... TMDL for Monitored Segment (counts/30 days) ..........................................................5-4 CHARTS Page A-1 .... Flow Comparison between Station 07029310 and Reach 08010207018 .................... AA-2 A-2 .... Model Output Under Existing Conditions for Reach 08010207021 ........................... AA-3 A-3 .... Model Output After Application of Reduction Scenario for Reach 08010207021...... AA-4 A-4 .... Model Output Under Existing Conditions for Reach 08010207018 ........................... AA-5 A-5 .... Model Output After Application of Reduction Scenario for Reach 08010207018...... AA-6 ___________________________________________________________________________iv