A , E , N LGAE UTROPHIC CONDITIONS AND UTRIENTS T M D L V OTAL AXIMUM AILY OADS FOR ENTURA R T IVER AND ITS RIBUTARIES CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD LOS ANGELES REGION 320 WEST 4TH STREET LOS ANGELES, CALIFORNIA 90013 REVISED DRAFT: NOVEMBER 16, 2012 i TABLE OF CONTENTS 1. INTRODUCTION ..............................................................................................................................1 1.1 REGULATORY BACKGROUND .............................................................................................................. 1 1.2 ELEMENTS OF A TMDL ...................................................................................................................... 2 1.3 ENVIRONMENTAL SETTING ................................................................................................................. 3 2. PROBLEM IDENTIFICATION .......................................................................................................9 2.1 NUTRIENT ENRICHMENT PROBLEMS IN RIVERS & ESTUARIES .............................................................. 9 2.2 WATER QUALITY STANDARDS........................................................................................................... 14 2.3 WATER QUALITY DATA SUMMARY ................................................................................................... 17 2.4 PROBLEM STATEMENT ..................................................................................................................... 30 3. NUMERIC TARGETS .....................................................................................................................32 4. SOURCE ASSESSMENT ................................................................................................................36 4.1 POINT SOURCES ............................................................................................................................... 39 4.2 NONPOINT SOURCES ......................................................................................................................... 45 4.3 SUMMARY OF SOURCE ASSESSMENT ................................................................................................... 57 5. LINKAGE ANALYSIS ....................................................................................................................59 5.1 CRITICAL CONDITION....................................................................................................................... 59 5.2 LINKAGE ANALYSIS .......................................................................................................................... 61 6. POLLUTANT ALLOCATIONS AND TMDLS ............................................................................73 6.1 DRY-WEATHER ALLOCATIONS .......................................................................................................... 73 6.2 WET-WEATHER ALLOCATIONS ......................................................................................................... 79 6.3 MARGIN OF SAFETY ....................................................................................................................80 7. IMPLEMENTATION ......................................................................................................................82 7.1 IMPLEMENTATION OF WLAS ............................................................................................................ 82 7.2 IMPLEMENTATION OF LAS ................................................................................................................ 85 7.3 POTENTIAL IMPLEMENTATION STRATEGIES AND ASSOCIATED COSTS ................................................ 88 7.4 MONITORING PROGRAM ................................................................................................................... 97 7.5 IMPLEMENTATION SCHEDULE ........................................................................................................... 98 8. REFERENCES ...............................................................................................................................101 ii LIST OF TABLES Table 1-1 CWA Section 303(d) list of algae, eutrophic conditions, and nitrogen impairments in the Ventura River and its tributaries ............................................................................................................ 1 Table 1-2 Land Uses of Ventura River Watershed ........................................................................................ 5 Table 2-1 Beneficial Uses of the Ventura River Watershed ........................................................................ 15 Table 2-2 Impairments addressed by this TMDL ........................................................................................ 31 Table 3-1 TMDL Numeric Targets ............................................................................................................... 32 Table 3-2 CA NNE Beneficial Use Risk Categories ..................................................................................... 33 Table 3-3 Stream Nutrient TMDLs in Other Regions Where the Biostimulatory Substances Narrative Water Quality Objective were Applied ................................................................................................ 35 Table 4-1 Drainage Areas (acres) for Various Land Uses in the Ventura River Watershed ................... 39 Table 4-2 Summary of NPDES Permits in the Ventura River Watershed ................................................ 40 Table 4-3 Summary of annual rainfall data in the Ventura River Watershed from 1987 through 2007 (Tetra Tech, 2008) .................................................................................................................................. 41 Table 4-4 Runoff coefficients for various land uses ..................................................................................... 42 Table 4-5 Nutrient EMCs for various land uses (VCSQMD, 2001; VCWPD, 2010 and 2011; and Kayhanian et al., 2002) ........................................................................................................................... 42 Table 4-6 Wet-weather TN and TP loading (lb/year) from stormwater discharges ................................. 43 Table 4-7 Dry-weather TN and TP loading (lb/year) from dry-weather urban runoff ............................ 44 Table 4-8 TN and TP loading from Ojai Valley WWTP (OVSD, 2000-2012) ........................................... 44 Table 4-9 Concentrations of nutrients in wet-weather runoff for various agricultural land uses (VCAILG, 2008, 2009, 2010, 2011) ........................................................................................................ 46 Table 4-10 Annual wet-weather nitrogen loading (lb/year) from agricultural land uses ......................... 46 Table 4-11 Annual wet-weather phosphorus loading (lb/year) from agricultural land uses ................... 46 Table 4-12 Dry-weather nitrogen loading (lb/year) from agriculture land uses ....................................... 47 Table 4-13 Dry-weather phosphorus loading (lb/year) from agriculture land uses ................................. 48 Table 4-14 Wet-weather nitrogen loading (lb/year) from horses/livestock ............................................... 49 Table 4-15 Wet-weather phosphorus loading (lb/year) from horses/livestock .......................................... 49 Table 4-16 Daily nutrient waste production rates for horses (ASAE, 2003) ............................................. 50 Table 4-17 Dry-weather nutrient loading from horses in the Ventura River Watershed ........................ 50 Table 4-18 Adjusted open space areas .......................................................................................................... 54 Table 4-19 Wet-weather TN and TP loading (lb/year) from open space ................................................... 54 Table 4-20 Dry-weather TN and TP loading (lb/year) from open space ................................................... 55 Table 4-21 Summary of TN loading for all sources/land uses in the Ventura River watershed .............. 58 Table 4-22 Summary of TP loading for all sources/land uses in the Ventura River watershed .............. 58 Table 5-1 Bathtub inputs ............................................................................................................................... 68 Table 5-2 BATHTUB-predicted phytoplankton and nutrient concentrations compared to measured nutrient concentrations .......................................................................................................................... 71 Table 5-3 Predicted biological indicators based on Bight ’08 Empirical Relationships ........................... 72 Table 6-1 Dry weather WLAs and LAs for TN ............................................................................................ 75 Table 6-2 Dry weather WLAs and LAs for TP ............................................................................................ 75 Table 6-3 Dry-weather WLAs for Ventura County MS4 and Caltrans .................................................... 76 Table 6-4 Dry-weather WLA for general industrial and construction stormwater permittees ............... 76 Table 6-5 Dry-weather LAs for Agriculture ................................................................................................ 78 Table 6-6 Dry-weather LAs for Horse Facilities and Intensive Livestock Operations ............................. 78 Table 6-7 Wet-weather Allocations ............................................................................................................... 80 Table 6-8 Ojai Valley WWTP Wet-weather WLAs .................................................................................... 80 Table 7-1 Ojai Valley WWTP interim dry-weather WLAs ........................................................................ 83 Table 7-2 Summary of vegetated swales costs .............................................................................................. 89 Table 7-3 Summary of alum injection costs ................................................................................................. 90 Table 7-4 Summary of storm water constructed wetland costs .................................................................. 90 Table 7-5 Summary of micro-irrigation costs .............................................................................................. 93 Table 7-6 Summary of fencing costs ............................................................................................................. 94 Table 7-7 Summary of watering facilities costs ............................................................................................ 94 Table 7-8 Summary of anaerobic biodigester systems costs ....................................................................... 95 Table 7-9 Implementation Schedule............................................................................................................ 959 iii LIST OF FIGURES Figure 1-1 Major Surface Waters in Ventura River Watershed .................................................................. 4 Figure 1-2 Land Uses of the Ventura River Watershed ................................................................................ 6 Figure 1-3 Annual rainfall at Ojai County Fire Station ................................................................................ 7 Figure 1-4 Stream Flow in Ventura River at Foster Park and Effluent Discharge from Ojai Valley WWTP (Klose et al., 2009) ....................................................................................................................... 7 Figure 2-1 Conceptual Model for Rivers ...................................................................................................... 11 Figure 2-2 Conceptual Model for Estuaries ................................................................................................. 13 Figure 2-3 Pre-dawn dissolved oxygen measurements during the growing season, 2008 through 2011 . 19 Figure 2-4 Estuary DO Measurements ......................................................................................................... 20 Figure 2-5 Main Street DO Measurements .................................................................................................. 20 Figure 2-6 Foster Park DO Measurements .................................................................................................. 20 Figure 2-7 San Antonio Creek DO Measurements ...................................................................................... 21 Figure 2-8 Ventura River above San Antonio Creek A Creek DO Measurements .................................. 21 Figure 2-9 Matilija Creek DO measurements .............................................................................................. 21 Figure 2-10 North Fork Matilija Creek Do Measurements ........................................................................ 21 Figure 2-11 Nitrate Concentration Upper Watershed ................................................................................ 23 Figure 2-12 Nitrate Concentration lower watershed ................................................................................... 23 Figure 2-13 Phosphate Concentration Upper Watershed ........................................................................... 23 Figure 2-14 Phosphate Concentration Lower Watershed ........................................................................... 23 Figure 2-15 OVSD Effluent TIN Concentration 1979-2009 ........................................................................ 24 Figure 2-16 Ventura River TIN Concentration Downstream OVSD 1979-2009 ...................................... 24 Figure 2-17 Algal Biomass Ventura River Watershed, 2008 ...................................................................... 25 Figure 2-18 Algal Biomass Ventura River Watershed, 2008-2011 ............................................................. 27 Figure 2-19 Main Street Bridge 2005 ............................................................................................................ 28 Figure 2-20 Main Street Bridge 2008 ............................................................................................................ 29 Figure 2-21 Percent Cover of Different Algal Types (UCSB, 2008) ........................................................... 30 Figure 4-1 Ventura River Subwatershed ...................................................................................................... 37 Figure 4-2 Potential OWTS in the Ventura River watershed (LWA, 2011) .............................................. 53 Figure 5-1 Distribution of Flows throughout the Ventura River (Tetratech, 2012) ................................. 59 Figure 5-2 Comparison of calculated flow rate with 2008 observed data for calibration ........................ 62 Figure 5-3 Comparison of calculated nitrate-nitrogen with 2008 observed data for calibration ............ 62 Figure 5-4 Comparison of calculated flow rate with 2007 observed data for validation .......................... 63 Figure 5-5 Comparison of calculated nitrate-nitrogen with 2007 observed data for validation .............. 63 Figure 5-6 Comparison of calculated flow rate with 2006 observed data for validation .......................... 64 Figure 5-7 Comparison of calculated nitrate-nitrogen with 2006 observed data for validation .............. 64 Figure 5-8 Predicted nitrate concentrations based on validated model ..................................................... 65 Figure 5-9 Predicted phosphate concentrations based on validated model ............................................... 65 Figure 5-10 Relationship between chlorophyll a and total nitrogen in the Ventura River ...................... 66 Figure 5-11 Areal Extent of the Ventura River Estuary ............................................................................. 69 Figure 5-12 Estimated Depth of the Ventura River Estuary ...................................................................... 70 Figure 6-1 TN Reduction scenario to attain allowable in-stream TN concentrations .............................. 74 Figure 6-2 TP Reduction scenario to attain allowable in-stream TP concentrations ............................... 74 Figure 7-1 Ojai WWTP Flows (MGD) from 2000-2011 .............................................................................. 83 iv LIST OF ACRONYMS ASSETS Assessment of Estuarine Trophic Status BMP Best Management Practice BURC Beneficial Use Risk Category Caltrans California Department of Transportation CASQA California Stormwater Quality Association CEQA California Environmental Quality Act CFR Code of Federal Regulations CFS Cubic Feet per Second CWA Clean Water Act CZARA Coastal Zone Act Reauthorization Amendments DEM Digital Elevation Model DO Dissolved Oxygen DWR Department of Water Resources GIS Geographic Information System EPA Environmental Protection Agency FOTG Field Office Technical Guide LA Load Allocation LARWQCB Los Angeles Regional Water Quality Control Board LiDAR Light Detection and Ranging MANAGE Measured Annual Nutrient loads from Agricultural Environments MGD Million Gallons per Day mL Milliliters MOU Memorandum of Agreement MS4 Municipal Separate Storm Sewer System NAIP National Agriculture Imagery Program NEAA National Estuarine Eutrophication Assessment NOAA National Oceanic and Atmospheric Administration NMFS National Marine Fisheries Service NNE Nutrient Numeric Endpoint NPDES National Pollutant Discharge Elimination System NPS Nonpoint Source NRCS Natural Resources Conservation Service NTS Natural Treatment System OWTS Onsite Wastewater Treatment Syatem OVSD Ojai Valley Sanitary District QAPP Quality Assurance Project Plan REC-1 Water Contact Recreational Use REC-2 Non-contact Recreational Use SBCK Santa Barbara Channelkeeper SCAG Southern California Association of Governments SCCWRP Southern California Coastal Water Research Project SMC Southern California Stormwater Monitoring Coalition SWRCB State Water Resources Control Board TIN Total Inorganic Nitrogen TN Total Nitrogen TP Total Phosphorus TMDL Total Maximum Daily Load v UCSB University of California, Santa Barbara US EPA Unites States Environmental Protection Agency USDA United States Department of Agriculture USGS United States Geological Survey VCAILG Ventura County Agricultural Irrigated Lands Group VCWPD Ventura County Watershed Protection District WDR Waste Discharge Requirement WLA Waste Load Allocation WQA Water Quality Assessment WQO Water Quality Objective WWTP Wastewater Treatment Plant vi 1. INTRODUCTION The Ventura River Estuary and the Ventura River (including its tributaries), located in Ventura County, are identified on the 1998, 2002, 2006, and 2010 Clean Water Act (CWA) Section 303(d) list of impaired waterbodies due to algae, eutrophic conditions, low dissolved oxygen, and nitrogen (Table 1-1). The CWA requires the development of Total Maximum Daily Loads (TMDLs) to restore impaired waterbodies to fully support their beneficial uses. This document provides the background information used by the California Regional Water Quality Control Board, Los Angeles Region (Los Angeles Regional Board) in the development of the TMDL for Algae, Eutrophic Conditions, and Nutrients in the Ventura River and its Tributaries. Table 1-1 CWA Section 303(d) list of algae, eutrophic conditions, and nitrogen impairments in the Ventura River and its tributaries Waterbody Name Pollutant(s) Ventura River Estuary Algae, Eutrophic Ventura River Reach 1 and 2 (Estuary to Weldon Canyon) Algae San Antonio Creek Nitrogen Cañada Larga Low Dissolved Oxygen As documented in this staff report, the algae and nutrient-related impairments are caused by excessive loading of nutrients, particularly nitrogen and phosphorus to Ventura River and its tributaries. 1.1 Regulatory Background Section 303(d) of the Clean Water Act (CWA) requires that “Each State shall identify those waters within its boundaries for which the effluent limitations are not stringent enough to implement any water quality standard applicable to such waters.” The CWA also requires states to establish a priority ranking for waters on the 303(d) list of impaired waters and establish TMDLs for such waters. The elements of a TMDL are described in 40 CFR sections 130.2 and 130.7 and Section 303(d) of the CWA, as well as in the U.S. Environmental Protection Agency guidance (U.S. EPA, 2000a). A TMDL defined as the “sum of the individual waste load allocations for point sources and load allocations for nonpoint sources and natural background” (40 CFR section 130.2) such that the capacity of the waterbody to assimilate pollutant loadings (the Loading Capacity) is not exceeded. TMDLs are also required to account for seasonal variations, and include a margin of safety to address uncertainty in the analysis. States must develop water quality management plans to implement the TMDL (40 CFR section 130.6). The U.S. EPA has oversight authority for the 303(d) program and is required to review and either approve or disapprove the TMDLs submitted by states. If the 1 U.S. EPA disapproves a TMDL submitted by a state, U.S. EPA is required to establish a TMDL for that waterbody. A schedule for development of TMDLs in the Los Angeles Region was established in a consent decree (Heal the Bay Inc., et al. v. Browner C 98-4825 SBA) approved on March 22, 1999. The consent decree combined waterbody pollutant combinations in the Los Angeles Region into 92 TMDL analytical units. In accordance with the consent decree, this TMDL addresses the waterbodies in analytical unit 88. This document summarizes the analyses performed and presents the TMDL for Algae, Eutrophic Conditions, and Nutrients in the Ventura River and its Tributaries. 1.2 Elements of a TMDL There are seven elements of a TMDL. Sections 2 through 7 of this document are organized such that each section describes one of the elements, with the analysis and findings of this TMDL for that element. The elements are: (cid:1) Section 2: Problem Identification. This section reviews the data used to add the waterbody to the 303(d) list, and summarizes existing conditions using that evidence along with any new information acquired since the listing. This element identifies those beneficial uses that are not supported by the waterbody; the water quality objectives (WQOs) designed to protect those beneficial uses; and summarizes the evidence supporting the decision to list each reach, such as the number and severity of exceedances observed. (cid:1) Section 3: Numeric Targets. The numeric targets for this TMDL are based upon the WQOs described in the Basin Plan. (cid:1) Section 4: Source Assessment. This section develops the quantitative estimate of nutrient loading from point sources and nonpoint sources to the Ventura River and its tributaries. (cid:1) Section 5: Linkage Analysis. This analysis shows how the sources of pollutants discharged to the waterbody are linked to the observed conditions in the impaired waterbody. (cid:1) Section 6: Pollutant Allocations. Each pollutant source is allocated a quantitative load that it can discharge to meet the numeric targets. Point sources are assigned waste load allocations (WLAs) and nonpoint sources are assigned load allocations (LAs). Allocations are designed such that the waterbody will not exceed numeric targets for any of the compounds or related effects. Allocations are based on critical conditions, so that the allocated pollutant loads may be expected to remove the impairments at all times. (cid:1) Section 7: Implementation and Monitoring. This section describes the plans, regulatory tools, or other mechanisms by which the WLAs and LAs may be achieved. The TMDL provides cost estimates to meet the WLAs and LAs. The TMDL includes a monitoring program to assess TMDL effectiveness and attainment of water quality standards. It also describes special studies to address 2 uncertainties in assumptions made in the development of this TMDL and the process by which new information may be used to refine the TMDL. 1.3 Environmental Setting The Ventura River watershed (Figure 1-1) is located in the northwestern portion of Ventura County with a small portion in the southeastern portion of Santa Barbara County. The watershed drains a fan-shaped area of about 220 square miles with an elevation from 6,000 feet to sea level. The Ventura River has several major tributaries, including Matilija Creek, North Fork Matilija Creek, San Antonio Creek, Coyote Creek and Cañada Larga. Matilija creek (15 miles) drains the Santa Ynez Mountains as it flows to the Matilija Reservoir and the Matilija Dam. The creek continues below the dam for about one half mile before it joins North Fork Matilija Creek. North Fork Matilija Creek, which is about 12 miles long, generally follows Highway 33 in the Los Padres National Forest until it joins Matilija Creek. The Ventura River starts at the confluence of Matilija Creek and North Fork Matilija Creek. The Ventura River then flows for about 16 miles in a southerly direction to the estuary and the Pacific Ocean. The Ventura River has intermittent direct discharge to the ocean; longshore transport of sand can cause a sand bar to form at the mouth of the estuary in the late summer and early fall. The Ventura River Estuary extends from the ocean to approximately 150 meters upstream of the railroad bridge based on tidal influence. The Estuary includes an open water area that is separated from the ocean by a berm that forms during the dry season. The berm is breached during storm events and slowly rebuilds through the summer, sometimes not fully building until August or September. The Estuary is flushed by tides when the berm is open and is dominated by slightly brackish to freshwater when the berm is closed (Ventura River Watershed State of the Watershed Report). 3 Figure 1-1 Major Surface Waters in Ventura River Watershed The watershed topography is characterized by rugged mountains in the upper basins transitioning to less steep areas and valleys in the lower watershed. The gradient in the watershed ranges from about 150 feet per mile at the headwaters to about 40 feet per mile near mouth of the river. The U.S. Bureau of Reclamation classifies the watershed topography as fifteen percent valley, forty percent foothill, and forty-five percent mountain. The highest point in the watershed is at 6,025 feet in the Santa Ynez Mountains. There are two reservoirs within the watershed: Lake Casitas and Matilija Reservoir. Lake Casitas serves as an important source of municipal supply water and is a popular recreation 4