April 25, 2005 Calleguas Creek Watershed OC Pesticides and PCBs TMDL Technical Report Submitted to Los Angeles Regional Quality Control Board Prepared by Larry Walker Associates on behalf of the Calleguas Creek Watershed Management Plan Table of Contents 1 Introduction ...........................................................................................................................................1 1.1 Regulatory Background................................................................................................................3 1.2 Calleguas Creek TMDL Stakeholder Participation Process .........................................................4 1.3 Elements of a TMDL.....................................................................................................................5 2 Problem Statement ...............................................................................................................................6 2.1 Environmental Setting ..................................................................................................................6 2.2 Water Quality Standards ............................................................................................................13 2.3 Beneficial Uses ..........................................................................................................................13 2.4 Water Quality Objectives............................................................................................................14 2.5 Antidegradation..........................................................................................................................15 2.6 Basis For Listings.......................................................................................................................15 2.7 303(d) Listing Data.....................................................................................................................18 3 Current Conditions..............................................................................................................................23 3.1 Regulatory Status.......................................................................................................................23 3.2 Sources of Monitoring Data........................................................................................................23 3.3 Summary of Monitoring Data......................................................................................................24 3.4 Definition of Category-1 and Category-2 Constituents ...............................................................30 3.5 Status of Category-1 Constituents..............................................................................................31 3.6 Conclusions................................................................................................................................48 4 Numeric Targets .................................................................................................................................50 4.1 Water Column Targets ...............................................................................................................51 4.2 Fish Tissue Targets....................................................................................................................51 4.3 Sediment Targets.......................................................................................................................52 4.4 Protection of Wildlife Habitat and Endangered Species .............................................................53 4.5 Alternatives Considered .............................................................................................................55 5 Source Analysis ..................................................................................................................................56 5.1 Data Resources and Analysis ....................................................................................................57 5.2 Land Use....................................................................................................................................63 5.3 Historical Assessment of Category-1 Constituents.....................................................................68 5.4 OC Loads in Water by Source....................................................................................................78 5.5 Conclusions................................................................................................................................81 6 Linkage Analysis.................................................................................................................................82 6.1 Conceptual Model / Fate and Transport.....................................................................................82 6.2 Linkage Between OC Loads, Targets, and Beneficial Uses.......................................................87 7 TMDL and Allocations.........................................................................................................................94 7.1 Critical Conditions ......................................................................................................................96 7.2 Existing and Allowable Concentrations ......................................................................................96 7.3 Waste Load Allocations and Load Allocations............................................................................99 7.4 Background Load .....................................................................................................................106 7.5 Margin of Safety.......................................................................................................................106 7.6 Attainability Analysis.................................................................................................................107 7.7 Future Growth ..........................................................................................................................110 Calleguas Creek Watershed i April 25, 2005 OC Pesticides and PCBs TMDL 8 Implementation Plan .........................................................................................................................113 8.1 Waste load Allocation Implementation .....................................................................................113 8.2 Load Allocation Implementation ...............................................................................................115 8.3 Special Studies ........................................................................................................................117 8.4 Reevaluation of WLAs and LAs................................................................................................119 8.5 Monitoring Plan ........................................................................................................................120 8.6 Implementation Schedule.........................................................................................................122 8.7 Adaptive Management .............................................................................................................124 8.8 Economic Analysis of Implementation......................................................................................124 9 References .......................................................................................................................................128 Table of Appendices Appendix I – Planning Species for the Calleguas Creek Watershed Evaluation Study..............................134 Appendix II – Least Tern and Clapper Rail Data from Point Mugu Navy Base ..........................................135 Appendix III - Land Use in the Calleguas Creek Watershed by Subcategory ............................................136 Table of Figures Figure 1. Map of Calleguas Creek Watershed, showing 303d listed reaches...............................................2 Figure 2. Detected values for DDE in water, sediment, and fish tissue. .....................................................33 Figure 3. Detection limits for all DDE records in the CCW Database..........................................................33 Figure 4 - Detected values for Chlordane in water, sediment, and fish tissue .............................................39 Figure 5. Detected values for Dieldrin in sediment and fish tissue..............................................................41 Figure 6 - Detected values for PCBs in water, sediment, and fish tissue.....................................................44 Figure 7. Detected values for Toxaphene in water, sediment, and fish tissue ............................................46 Figure 8. Generalized conceptual model of sources and pathways of OCs in the CCW. ...........................56 Figure 9. Land Use in CCW........................................................................................................................63 Figure 10. Land Use in the Calleguas Creek Watershed, 1932..................................................................65 Figure 11. Land Use in the Calleguas Creek Watershed, 1969..................................................................66 Figure 12. Land Use in the Calleguas Creek Watershed, 2000..................................................................66 Figure 13. Urban Land Uses in the Calleguas Creek Watershed. ..............................................................67