APPENDIX F. Receiving Water Conditions, Potential Impacts of MS4 Discharges, and Priority Water Quality Conditions in the San Dieguito River WMA

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1 APPENDIX F Receiving Water Conditions, Impacts of MS4 Discharges, and Priority Water Quality Conditions in the San Dieguito River WMA

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3 Appendix F Receiving Water Conditions, Impacts of MS4 Discharges, and Priority Water Quality Conditions in the San Dieguito River WMA Table of Contents \- I Table F-1 Table F-2 Table F-3 Page Receiving Water Conditions and Impacts of MS4 Discharges in the San Dieguito River WMA F-3 Priority Water Quality Conditions in the San Dieguito River WMA Subwatersheds F-5 Evaluation of Priority Water Quality Conditions in the San Dieguito River WMA F-9 Page F-i

4 Appendix F Receiving Water Conditions, Impacts of MS4 Discharges, and Priority Water Quality Conditions in the San Dieguito River WMA \- I Intentionally Left Blank Page F-ii

5 Appendix F Receiving Water Conditions, Impacts of MS4 Discharges, and Priority Water Quality Conditions in the San Dieguito River WMA This appendix contains details of the analysis of receiving water conditions (Section 2.1), impacts from MS4 discharges (Section 2.2), and the factors that were evaluated to develop the final list of priority water quality conditions and high priority water quality conditions. The information is presented in three tables, which are described below. Table F-1: Receiving Water Conditions and Impacts of MS4 Discharges in the San Dieguito River WMA Table F-1 presents all identified receiving water conditions in the San Dieguito River WMA and the potential impacts of the MS4 discharges. These conditions were identified as described in Sections 2.1 and 2.2 based on the considerations detailed in the table. These include: Available receiving water data (current or historic) or regulatory drivers that support the condition. A check mark in the table indicates that samples have exceeded water quality objectives or the (d) list or a TMDL identifies the waterbody as impaired. Where possible, the data were divided by temporal extent (wet- or dry-weather). Available current or historic MS4 indicating that the MS4 potentially causes or contributes to the condition. A check mark indicates that samples collected from the MS4 during wet- or dry-weather have exceeded water quality objectives. MS4 data from the subwatershed was typically used for this consideration; data for MS4 discharges directly to the receiving water body in question are rarely available. Identification of the MS4 as a source of the condition in the (d) list or a TMDL. The factors that led to the determination that the condition exists and was therefore included in the table. Table F-2: Priority Water Quality Conditions in the San Dieguito River WMA Subwatersheds Table F-2 presents the following information for each priority water quality condition per the MS4 Permit (Provision B.2.b): The beneficial use impairment(s) associated with the priority water quality condition; The pollutant or stressor causing the beneficial use impairment, if known; The temporal extent of the priority water quality condition (dry and/or wet weather); Page F-1

6 Appendix F Receiving Water Conditions, Impacts of MS4 Discharges, and Priority Water Quality Conditions in the San Dieguito River WMA The geographical extent of the priority water quality condition within the WMA, if known (based on the extent of the associated 303(d) listing or the location of the associated NPDES monitoring location); Lines of evidence leading to identification as a priority water quality condition, including evidence of MS4 discharges that may cause or contribute to the condition; and An assessment of the adequacy of the to characterize the factors causing or contributing to the priority water quality condition, including consideration of spatial and temporal variation. The table also lists the Responsible Agencies that potentially contribute to the condition. The contents of this table were determined by the assessment of the receiving water conditions and the MS4 impacts (presented in Table F-1). Table F-3: Evaluation of Priority Water Quality Conditions in the San Dieguito River WMA As described in Section 2.3, priority water quality conditions that were identified based on the methodology presented in Appendix A. The remaining priority water quality conditions were evaluated based on several factors to determine if they warranted elevation to high priority water quality conditions for this iteration of the Water Quality Improvement Plan. Table F-3 summarizes this evaluation. The priority water quality condition must meet all of the following criteria to be considered a high priority water quality condition: Supporting data are sufficient to characterize the receiving water condition. To be sufficient, multiple samples collected under quality controlled monitoring must have exceeded water quality objectives. Storm water or non-stormwater runoff is a predominant source. Samples or observations collected under quality controlled monitoring programs must indicate that MS4 discharges are a predominant source of the receiving water condition. Controllable by Responsible Agencies. The pollutant or stressor must be within the authority of the Responsible Agency to control. To be considered controllable, there must be a clear link between the MS4 contribution and the receiving water condition, and the potential strategies to address the condition must be applicable to the geographic extent of the condition. Cannot be addressed by strategies identified for other high priority water quality condition s. The condition was not elevated to a high priority water quality condition if strategies identified for other high priority water quality conditions are expected to address the condition. Page F-2

7 Appendix F Receiving Water Conditions, Impacts of MS4 Discharges, and Priority Water Quality Conditions in the San Dieguito River WMA Subwatershed Waterbody Condition San Dieguito River Above Sutherland Reservoir San Dieguito River Above Lake Hodges Santa Ysabel Creek (Above Sutherland Reservoir) Sutherland Reservoir Cloverdale Creek Green Valley Creek Kit Carson Creek Felicita Creek Near the NPDES Monitoring Stations Near the NPDES Monitoring Stations Table F-1 Receiving Water Conditions and Impacts of MS4 Discharges in the San Dieguito River WMA Receiving Water Data or Regulatory Drivers Support Consideration as a Receiving Water Condition Determining Factor(s) For Receiving Water Data MS4 Monitoring Data Indicates MS4 Impact Wet Wet MS4 Listed As Source on 303(d) or TMDL of WARM due to toxicity (d) Elevated to Priority Water Quality Condition? No; Toxicity cannot be identified as a priority water quality condition because the full impact of all environmental contributions including the MS4 have not been characterized. of MUN due to color (d) Wet, Yes of MUN due iron, manganese, and ph of WARM due to eutrophication 1 (nitrogen) of WARM due to eutrophication 1 (phosphorus) (d) (d) 1 of AGR due to TDS (d) and historical and current (d) and historical and current No; Iron not assessed under previous MS4 Permit. Manganese and ph were not elevated to a MS4 outfall priority by LTEA or WRMP. No; No MS4 data, and based on best professional judgment MS4 impacts on eutrophic conditions are not quantifiable. Yes Yes of MUN due to chloride (d) Yes of MUN due manganese and PCP of MUN due to sulfate (d) (d) and historical and current of MUN due to PCP (d) of MUN due to TDS (d) and historical and current of MUN due to aluminum (d) of MUN due to TDS 1 1 Fecal coliform exceedance at the NPDES receiving water (RW) stations Elevated Enterococcus levels at the NPDES RW stations Poor IBI scores at the NPDES RW stations Toxicity to C. dubia at the NPDES RW stations (d) and historical and current Historical and current and Bacteria TMDL at Pacific Ocean Shoreline Historical and current and Bacteria TMDL at Pacific Ocean Shoreline Historical and current Historical and current No; PCP not assessed under previous MS4 Permit. Manganese was not elevated to a MS4 outfall priority by LTEA or WRMP Yes No; PCP not assessed under previous MS4 Permit. Yes No; Aluminum not assessed under previous MS4 Permit Yes Yes Yes No; Poor IBI scores cannot be identified as a priority water quality condition because the full impact of all environmental contributions including the MS4 have not been characterized. No; Toxicity cannot be identified as a priority water quality condition because the full impact of all environmental contributions including the MS4 have not been characterized. Continued on next page Page F-3

8 Appendix F Receiving Water Conditions, Impacts of MS4 Discharges, and Priority Water Quality Conditions in the San Dieguito River WMA Subwatershed Waterbody Condition Receiving Water Data or Regulatory Drivers Support Consideration as a Receiving Water Condition Determining Factor(s) For Receiving Water Data MS4 Monitoring Data Indicates MS4 Impact Wet Wet MS4 Listed As Source on 303(d) or TMDL Elevated to Priority Water Quality Condition? San Dieguito River Above Lake Hodges San Dieguito River Below Lake Hodges San Dieguito River Pacific Ocean Shoreline at San Dieguito Lagoon Mouth at San Dieguito River Beach 2 of MUN due to color (d), public input Wet, Yes of MUN due to manganese, ph, and mercury (d), public input of MUN due to turbidity (d) and historical data of MUN due to eutrophication 1 (nitrogen and phosphorus) impairment of REC-1 due Enterococcus impairment of REC-1 due to fecal coliform 1 of WARM due to toxicity of WARM conditions due to eutrophication (ammonia) of WARM due to eutrophication (nitrogen) of WARM due to TDS of SHELL due to total coliform impairment of REC-1 due to indicator bacteria (Enterococcus, fecal coliform, and total coliform) 1. Only listed as a dry weather condition based on best professional judgment that wet weather impacts are not quantifiable. 2. Fletcher outfall, upstream of these waterbodies, has a low flow diverter that could potentially reduce dry weather discharge. = Criterion applies to temporal extent. = Criterion does not apply to temporal extent (d) and historical, current and public input (d), historical and current, and Bacteria TMDL at Shoreline (d), historical monitoring data, and Bacteria TMDL at Shoreline (d) and historical and current (d) and public input No; Manganese and mercury not assessed under previous MS4 Permit. ph was not elevated to a MS4 outfall priority by LTEA or WRMP. No; no MS4 data to justify designation as priority water quality condition. Yes Wet, Yes Wet, Yes Wet, Yes No; No MS4 data, and based on best professional judgment MS4 impacts on eutrophic conditions are not quantifiable (d) and public input Yes (d) and historical and current (d) Yes No; no MS4 data to justify designation as priority water quality condition. Bacteria TMDL Wet, Yes Page F-4

9 Appendix F Receiving Water Conditions, Impacts of MS4 Discharges, and Priority Water Quality Conditions in the San Dieguito River WMA Table F-2 Priority Water Quality Conditions in the San Dieguito River WMA Subwatersheds Data Gaps (6) ly Responsible Agencies Priority Water Quality Condition (1) Stressor(s) (2) Temporal Extent (3) San Dieguito River Above Sutherland Reservoir of MUN in Sutherland Reservoir Color, Wet San Dieguito River Above impairment of WARM in Cloverdale Creek of AGR in Cloverdale Creek of MUN in Green Valley Creek Eutrophic conditions (phosphorus) TDS Chloride, Wet Geographical Extent (4) Determining Factors (5) Urban runoff/storm sewers listed in (d) as source Urban runoff/storm sewers listed in (d) as sources; current and historical receiving water for downstream waterbodies; historical subwatershed level outfall monitoring data Urban runoff/storm sewers listed in (d) as sources; current and historical receiving water for downstream waterbodies; historical subwatershed level outfall monitoring data Historical subwatershed level outfall ; current and historical MS4 outfall. RW 1 MS4 2 City of Del Mar (DM) City of Escondido (E) City of Poway (P) City of Solana Beach (SB) City of San Diego (SD) County of San Diego (CO) Y Y Y Y Y Y Y Y Continued on next page Page F-5

10 Appendix F Receiving Water Conditions, Impacts of MS4 Discharges, and Priority Water Quality Conditions in the San Dieguito River WMA Data Gaps (6) ly Responsible Agencies Priority Water Quality Condition (1) Stressor(s) (2) Temporal Extent (3) Geographical Extent (4) Determining Factors (5) RW 1 MS4 2 City of Del Mar (DM) City of Escondido (E) City of Poway (P) City of Solana Beach (SB) City of San Diego (SD) County of San Diego (CO) San Dieguito River Above of MUN in Green Valley Creek Sulfates Urban runoff/storm sewers and natural sources listed in (d) as source; historical SMC receiving water monitoring data (limited); historical subwatershed level outfall Y Y of MUN in Kit Carson Creek TDS Current and historical receiving water for downstream waterbodies; current and historical MS4 outfall. Y Y of MUN in Felicita Creek TDS Urban runoff/storm sewers/agricultural return flows/ flow regulation and modification listed in (d) as sources; current and historical receiving water for downstream waterbodies; historical subwatershed level outfall Y Y of REC-1 Above Fecal coliform Enterococcus Wet Near NPDES monitoring locations Current and historical receiving water for wet weather; subwatershed level outfall for wet weather; Bacteria TMDL Current and historical receiving water for dry weather; subwatershed level outfall for dry weather; Bacteria TMDL N Y N Y Continued on next page Page F-6

11 Appendix F Receiving Water Conditions, Impacts of MS4 Discharges, and Priority Water Quality Conditions in the San Dieguito River WMA Data Gaps (6) ly Responsible Agencies Priority Water Quality Condition (1) Stressor(s) (2) Temporal Extent (3) San Dieguito River Above Geographical Extent (4) Determining Factors (5) RW 1 MS4 2 City of Del Mar (DM) City of Escondido (E) City of Poway (P) City of Solana Beach (SB) City of San Diego (SD) County of San Diego (CO) of MUN in Color Eutrophic conditions (nitrogen and phosphorus) Wet, San Dieguito River Below of REC-1 in San Dieguito River Indicator bacteria (Enterococcus and fecal coliform) Wet, and near NPDES monitoring locations (wet weather only) Urban runoff/storm sewers listed in (d) as source; public input Urban runoff/storm sewers listed in (d) as sources; current and historical receiving water and historical outfall ; public input Urban runoff as a potential source; current and historical receiving water Y Y N Y N Y of WARM in San Dieguito River Toxicity TDS Wet, and near NPDES monitoring locations (wet weather only) Urban runoff as a potential source; current and historical receiving water for downstream waterbodies Y 3 Y 3 Y 3 Y 3 Continued on next page Page F-7

12 Appendix F Receiving Water Conditions, Impacts of MS4 Discharges, and Priority Water Quality Conditions in the San Dieguito River WMA Data Gaps (6) ly Responsible Agencies Priority Water Quality Condition (1) Stressor(s) (2) 1. Are there gaps in the RW data used to characterize the priority water quality condition? (Y = yes; N = no). 2. Are there gaps in the MS4 data used to characterize the geographical contribution of the MS4 to priority water quality condition? (Y = yes; N = no). 3. The impact of the MS4 is unknown. Temporal Extent (3) San Dieguito River Below of WARM in San Dieguito River of REC-1 at Pacific Ocean Shoreline of REC-1 at Pacific Ocean Shoreline Eutrophic conditions (nitrogen) Indicator bacteria (Enterococcus and fecal coliform) Indicator bacteria (Enterococcus and fecal coliform) Wet overflow Wet, Geographical Extent (4) Determining Factors (5) Urban runoff as a potential source; public input RW 1 MS4 2 DM = City of Del Mar; E = City of Escondido; P = City of Poway; SB = City of Solana Beach; SD = City of San Diego; CO = County of San Diego City of Del Mar (DM) City of Escondido (E) City of Poway (P) City of Solana Beach (SB) City of San Diego (SD) County of San Diego (CO) Y 3 Y 3 MS4 discharges Bacteria TMDL N Y Pacific Ocean Shoreline at San Dieguito Lagoon Mouth Bacteria TMDL N N Page F-8

13 Appendix F Receiving Water Conditions, Impacts of MS4 Discharges, and Priority Water Quality Conditions in the San Dieguito River WMA Table F-3 Evaluation of Priority Water Quality Conditions in the San Dieguito River WMA Subwatershed San Dieguito River Above Lake Sutherland Priority Water Quality Condition 1 of MUN in Sutherland Reservoir impairment of WARM in Cloverdale Creek of AGR in Cloverdale Creek Stressor(s) (a) Supporting Data Is Sufficient to Characterize the Receiving Water Conditions (b) Storm Water/ Non-Storm Water Runoff Predominant Source (c) Controllable by Responsible Agencies 2 (d) Cannot Be Addressed by Identified Strategies Color Eutrophic conditions (phosphorus) Total dissolved solids San Dieguito River Above of MUN in Green Valley Creek of MUN in Kit Carson Creek of MUN in Felicita Creek of REC-1 Above 3 Chloride Sulfates Total dissolved solids Total dissolved solids Fecal coliform Enterococcus Continued on next page Page F-9

14 Appendix F Receiving Water Conditions, Impacts of MS4 Discharges, and Priority Water Quality Conditions in the San Dieguito River WMA Subwatershed Priority Water Quality Condition 1 Stressor(s) (a) Supporting Data Is Sufficient to Characterize the Receiving Water Conditions (b) Storm Water/ Non-Storm Water Runoff Predominant Source (c) Controllable by Responsible Agencies 2 (d) Cannot Be Addressed by Identified Strategies San Dieguito River Above San Dieguito River Below of MUN in of REC-1 (in San Dieguito River) 3 of WARM in San Dieguito River Color Eutrophic conditions (nitrogen and phosphorus) Indicator bacteria (Enterococcus and fecal coliform) Toxicity Total dissolved solids Eutrophic conditions (nitrogen) The criterion is met for the priority water quality condition. The criterion is not met for the priority water quality condition. 1. Priorities associated with a TMDL are considered high priority water quality conditions and are not included in this table 2. The priority water quality condition is considered controllable if two criteria are met: (1) There is a clear link between the MS4 contribution and the receiving water conditions, and (2) The potential strategies that apply to the potential stressor are applicable for the drainage area of the receiving water condition. 3. Bacteria TMDL only applicable at Pacific Ocean Shoreline. Page F-10