FINAL TEXAS COASTAL WATERS: NUTRIENT REDUCTION STRATEGIES REPORT Photo: Courtesy of Texas Parks and Wildlife Department 2014 Prepared for: TEXAS COMMISSION ON ENVIRONMENTAL QUALITY, TEXAS PARKS AND WILDLIFE DEPARTMENT, TEXAS GENERAL LAND OFFICE, U.S. DEPARTMENT OF THE INTERIOR, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, U.S. DEPARTMENT OF AGRICULTURE, U.S. ENVIRONMENTAL PROTECTION AGENCY Prepared by: AUGUST 2019 This page intentionally left blank FINAL TEXAS COASTAL WATERS: NUTRIENT REDUCTION STRATEGIES REPORT Prepared for: TEXAS COMMISSION ON ENVIRONMENTAL QUALITY TEXAS PARKS AND WILDLIFE DEPARTMENT TEXAS GENERAL LAND OFFICE U.S. DEPARTMENT OF THE INTERIOR NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION U.S. DEPARTMENT OF AGRICULTURE U.S. ENVIRONMENTAL PROTECTION AGENCY Prepared by: Austin, TX 78758 AUGUST 2019 Printed on Recycled Paper This page intentionally left blank Nutrient Reduction Restoration Strategies Report Table of Contents TABLE OF CONTENTS EXECUTIVE SUMMARY ......................................................................................................................... ES-1 SECTION 1 INTRODUCTION ................................................................................................................... 1-1 1.1 Background Information ..................................................................................................................... 1-1 SECTION 2 DEVELOPMENT OF INITIAL CRITERIA FOR TARGET WATERSHED IDENTIFICATION ........ 2-1 2.1 Data Collection .................................................................................................................................... 2-1 2.1.1 Atmospheric Deposition ....................................................................................................... 2-3 2.1.2 Fish Kills ................................................................................................................................ 2-3 2.2 Data Analysis ....................................................................................................................................... 2-3 2.2.1 Evaluating Water Quality Conditions ................................................................................... 2-3 2.2.2 Point Source Influences ..................................................................................................... 2-13 2.2.3 Dissolved Oxygen ................................................................................................................ 2-13 2.3 Consideration of Additional Characteristics for Prioritizing Watersheds ....................................... 2-21 SECTION 3 EVALUATION OF RECOMMENDED TARGET WATERSHEDS .............................................. 3-1 3.1 Watershed Descriptions ..................................................................................................................... 3-1 3.2 Lower Guadalupe River Watershed ................................................................................................... 3-1 3.2.1 Land Use and Land Cover .................................................................................................... 3-4 3.2.2 Beneficial Uses and Impairments, Other Ongoing Studies and Projects .......................... 3-4 3.3 San Fernando Creek Watershed ........................................................................................................ 3-7 3.3.1 Land Use and Land Cover .................................................................................................... 3-8 3.3.2 Beneficial Uses and Impairments, Other Ongoing Studies and Projects .......................... 3-8 3.4 Petronila Creek Watershed .............................................................................................................. 3-14 3.4.1 Land Use and Land Cover .................................................................................................. 3-14 3.4.2 Beneficial Uses and Impairments ...................................................................................... 3-14 3.5 Data Inputs for Nutrient Load Modeling .......................................................................................... 3-17 3.6 Other Factors Influencing Instream Nutrient Concentrations ........................................................ 3-19 3.7 Lower Guadalupe River Watershed - Nutrient Sources and Load Estimates ................................ 3-24 3.8 San Fernando Creek Watershed - Nutrient Sources and Load Estimates..................................... 3-28 3.9 Petronila Creek Watershed - Nutrient Sources and Load Estimates ............................................. 3-32 3.10 Watersheds Targeted for Nutrient Reduction Strategies ............................................................... 3-32 SECTION 4 EVALUATION OF RESTORATION APPROACHES ................................................................. 4-1 4.1 Petronila Creek Agriculture ................................................................................................................. 4-1 4.2 Cropland Management Strategies ..................................................................................................... 4-2 4.2.1 Group 1: Cropland BMPs Modeled in STEPL....................................................................... 4-3 4.2.2 Group 2: Other Cropland BMPs for Consideration ............................................................ 4-10 4.2.3 Group 3: Cropland BMPs Not Typically Used in Petronila Creek Watershed................... 4-11 i August 2019 Nutrient Reduction Restoration Strategies Report Table of Contents 4.3 Other Agricultural Management Strategies ..................................................................................... 4-12 4.4 Reducing Nutrient Loading Using Off-Field Management Strategies ............................................ 4-15 4.4.1 Targeting Privately-held Off-field Areas ............................................................................. 4-16 4.4.2 Road Rights-of-Way............................................................................................................. 4-18 4.5 Relative Load Reduction Potential ................................................................................................... 4-19 4.6 Planning Level Cost Analysis ............................................................................................................ 4-20 SECTION 5 IDENTIFICATION OF NUTRIENT REDUCTION STAKEHOLDERS ......................................... 5-1 5.1 Federal Partners ................................................................................................................................. 5-1 5.2 State Partners ..................................................................................................................................... 5-3 5.3 Regional Partners ............................................................................................................................... 5-5 5.4 Local Government Partners ................................................................................................................ 5-6 5.5 Local Partners ..................................................................................................................................... 5-6 5.6 Non-Governmental Organizations ...................................................................................................... 5-7 SECTION 6 SUMMARY OF FINDINGS .................................................................................................... 6-1 SECTION 7 REFERENCES ...................................................................................................................... 7-1 APPENDICES Appendix A Coastal Segments with Nutrient Concerns Appendix B Dissolved Oxygen Status History for Nutrient Impacted Coastal Waters Appendix C TPDES Permitted Outfalls Discharging to 15 Candidate Segments Appendix D STEPL Results: Estimated Nutrient Loads for 12-Digit HUCs Appendix E Scenario Descriptions of Relevant BMPs from the NRCS Field Office Technical Guide Appendix F Estimated Nutrient Load Reductions for Select Strategies in Petronila Creek ii August 2019 Nutrient Reduction Restoration Strategies Report Table of Contents LIST OF FIGURES Figure 1-1 Texas Coastal Zone Boundary ..................................................................................................... 1-3 Figure 2-1 Frequency Distribution of Average Percent Exceedance of Nutrient Screening Levels ........................................................................................................................................... 2-6 Figure 2-2 Texas Upper Coast Segments with Significant Nutrient Concerns (n=58) ............................. 2-11 Figure 2-3 Texas Lower Coast Segments with Significant Nutrient Concerns (n=58) ............................. 2-12 Figure 2-4 2014 Dissolved Oxygen ILOS for Nutrient-Impacted Coastal Waters (n=58) ........................ 2-14 Figure 2-5 Summary of the Watershed Prioritization Process .................................................................. 2-17 Figure 2-6 Non-urban, Nutrient-impacted Watersheds within the Coastal Zone Boundary (Northern Coast) ........................................................................................................................ 2-19 Figure 2-7 Non-urban, Nutrient-impacted Watersheds within the Coastal Zone Boundary (Central Coast) ..........................................................................................................................