### CALIFORNIA REGIONAL WATER QUALITY CONTROLBOARD SAN DIEGO REGION RESOLUTION**NO~ R9~2005~0019**  A RESOLUTIONADOPTING AN AMENDMENT TO THE WATER QUALITY CONTROLPLAN FOR THE SANDIEGO REGION TO INCORPORATE A TOTALMAXIMUM DAILY LOAD FORDISSOLVED COPPER INSHELTERISLAND YACHT BASIN, SANDIEGO BAY WHEREAS, The California Regional Water Quality Control Board, San Diego Region (hereinafter, Regional Board), finds that:
1. BASIN PLAN AMENDMENT: The proposed amendment ofthe Water Quality Control Plan for the San Diego Basin

- Region 9 (Basin Plan) described in the recitals below was developed in accordance with California Water Code (CWC) section 13240 et seq. 2. NECESSITY STANDARD [Government Code section 11353(b)]: This regulatory action meets the "Necessity" standard ofthe Administrative Procedures Act, Government Code, section 11353, subdivision (b). Amendment ofthe Basin Plan to establish and implement a Total Maximum Daily Load (TMDL) for Shelter Island Yacht Basin (SIYB) is necessary because the existing water quality does not meet applicable numeric water quality objectives for copper, or narrative water quality objectives for toxicity and pesticides. The federal Clean Water Act (CWA) section 303(d) requires the Regional Board to establish and oversee the implementation ofa TMDLunder the water quality conditions that exist in SIYB. This TMDLfor dissolved copperis necessary to ensure attainment ofapplicable water quality objectives and restoration ofbeneficial uses designated for SIYB. 3. CLEANWATERACT SECTION303(d): The SIYB portion ofSan Diego Bay was placed on the Clean Water Act section 303(d) list ofimpaired waters in 1996 due to elevated levels ofdissolved copper in the water column. 4. BENEFICIAL USE IMPAIRMENTS: SIYB supports the same suite ofbeneficial uses as San Diego Bay. The most sensitive beneficial uses are those designated for protection of marine aquatic life and aquatic dependent wildlife as described in the Basin Plan definition of the marine habitat (MAR) and wildlife habitat (WILD) beneficial uses. The MAR and·

· WILD beneficial uses ofSIYB arethreatened orimpaired due to elevated levels ofdissolved

copper.**5~** WATER QUALITY OBJECTIVES: The water quality objectives for copper in SIYB specify that concentrations in seawater for dissolved copper should not exceed

. 3.1 micrograms/liter (!lg/L) for continuous or chronic exposures (not to be exceeded over a four-day average), and4.8 !lg/Lofcopper for briefor acute exposures (not to be exceeded over a one-hour average). These water quality objectives are based on, and equal, to the California Toxics Rule (CTR) water quality criteria for dissolved copperpromulgatedby theUnited States Environmental Protection Agency (USEPA). The USEPA's CTR criteria are thelegally applicable water quality standards in the State ofCalifornia for inland surface waters, enclosedbays, and estuaries for all purposes and programs underthe CWA.
In addition, the Basin Plan establishes the following narrative water quality objectives for "toxicity" and "pesticides" to ensure the protection ofthe MAR and WILD beneficial uses. Toxicity Objective: All waters shall be maintain.edfree of toxic substances in concentrations thatare toxic to, orthatproduce detrimentalphysiological responses in human, plant, animal, oraquatic life. Compliance with this objective will be determined by use of indicator organisms, analyses of species diversity, population density, growth anomalies, bioassays of appropriate duration, orother appropriate methods as spec{fied by the Regional Board. The survival of aquatic life in suiface waters subjectedto a waste discharge orother controllable water factors, shall not be less than that for the same water body in areas unaffected by the waste discharge or, when necessary,for othercontrol water that is consistent with requirements specified in USEPA, State WaterResources Control Board (State Board) orotherprotocol authorized by the Regional Board. Asa minimum, compliance with this objective as stated in theprevious sentence shall be evaluatedwith a 96-houracute bioassay.
In addition, effluent limits based upon acute bioassays of effluents will beprescribedwhere appropriate, additional numerical receiving water objectivesfor specific toxicants will be

· establishedas sufficientdata become available, andsource control of toxic substances will be encouraged. Pesticide Objective: No individualpesticide orcombination of pesticides shall bepresent in the watercolumn, sediments, or biota at concentration(s) that adversely affectbeneficial uses. Pesticides shall not bepresent at levels that will bioaccumulate in aquatic organisms to levels harmful to human health, wildlife oraquatic organisms. Meeting the numeric water quality objectives for copper will ensure that the narrative toxicity and pesticides objectives are met in the water column with respect to copper. 6. NUMERIC TARGETS: TMDLNumeric Targets interpret and implement water quality standards (i.e., numeric and narrative water quality objectives and beneficial uses) and are established at levels necessary to achieve water quality standards. The Regional Board has setthe copper TMDLNumeric Targets for both the numeric and narrative water quality objectives equal to the numeric water quality objectives for copper cited in Finding 5. The numeric targets for dissolved copper are 3.1 ).lg/L for continuous or chronic exposure (4-day average) and4.8 ).lg/L (1-hour average) for briefor acute exposures. Attainment ofthe TMDLnumeric targets will result in attainment of water quality standards in SIYB.
7. SOURCES OFDISSOLVED COPPER: Approximately 98 percent ofthe total copper loadingto SIYB originates from copper-based antifouling paints applied to the hulls of recreational vessels mooredin SIYB marinas. Ofthis total, 93 percent is attributable to

2copper entering the water column through passive leaching ofcopper from antifouling paints. The remaining five percent enters the water column during periodic underwaterhull cleaning ofrecreational vessel hulls in the marinas. Fourother insignificant sources ofcopper were identified in the TJviDL source analysis including urban runoff, direct atmospheric deposition, marine sediment and background. 8. WATER QUALITY OBJECTIVE VIOLATIONS: Elevated dissolved copper concentrations in SIYB have been sustained overtime through continuous passive leaching ofcopper from antifouling paints. The effects ofthese discharges on waterquality are exacerbated by factors such as a) the large number ofvessels congregated in SIYB marinas (approximately 2,200 vessels); b) the large combined surface area ofvessel hulls leaching copper; and c) reduced tidal flushing caused by the configuration ofthe enclosed basin. Furthermore, since recreational vessels spend most oftheir time moored in marinas, most of the copper from antifouling paints on the vessel hulls is released in the marinas. Sampling surveys conductedby the Regional Board in SIYB during 1994 and 2000 documented water column concentrations as high as12 J,.lg/L and 8 J,.lg/L ofcopper, respectively. 9. ADVERSE EFFECTS OF COPPER: Copperis used as the bioicide in antifouling paints because ofits known toxicity to marine aquatic life. At relatively low concentration levels, ·copperis toxic to aquatic organisms. Coppertoxicity to aquatic life varies between species and within individual species life stages. The early life stages offish, bivalves and ·echinoderms are especially vulnerable to coppercontamination. Copper tends to accumulate ·in sediment, threatening the benthic life at SIYB. Copperin the sediment may need to be

removed through human intervention, such as dredging which can be very costly. Because of these adverse affects ofcopper, the use ofcopper-based antifouling paints is restricted or banned in parts ofEurope. 10. TOTAL MAXIMUMDAILYLOAD: [40 Code ofFederal Regulations (CPR), section 130.2(i)] The TMDLfor copper discharges into SIYB is calculated to be 1.6 kilograms of copperper day (kg/day), or 567 kilograms ofcopperper year (kg/year). The TMDLis defined as the maximum amount ofcopper that SIYB can receive and still attain water quality objectives and protection ofdesignated beneficial uses. The TMDLis comprised of the sum of all individual Wasteload Allocations (WLAs) for point source discharges of copper, the sum of all Load Allocations (LAs) for nonpoint source discharges ofcopper, and background. TheTMDL includes a margin of safety (MOS) that takes into account any uncertainties in the TMDL calculation. (i.e. TMDL

## = WLAs +LAs+MOS). The TMDL calculations also account for seasonal variations andcritical conditions. 11. ALLOCATIONS AND REDUCTIONS: A 76 percent overall reduction ofresidual copper loading to SIYB is required to meet the TMDL of567 kg/year. The assigned allocations from each source translate into a percent reduction ofdissolved copper from current loading. Loading due to passive leaching mustbe reduced by 81 percent from current loading. Loading due to underwater hull cleaning must bereduced by 28 percent from current loading. From an overall perspective, passive leaching loading must be reducedby 75 percent from the combined total loading of all sources to SIYB. Underwater hull cleaning



### 3loading must be reduced by one percent from the combined total loading ofall sources to SIYB.
12. DISCHARGERS: The San Diego Unified Port District (Port), SIYB marina owners/operators, persons owning boats moored in SIYB, and SIYB underwaterhull cleaners are accountable for the discharges ofcopperfrom boat hull antifouling paints to SIYB. To a much lesser extent, the City of San Diego (City) also discharges copperfrom its Municipal Separate Storm Sewer Systems (MS4s).
13. IMPLEMENTATIONACTIONS: Strategies that the Regional Board could take to implement the TMDL are described in the Basin Plan Amendment and Technical Report for Total Maximum Daily Load forDissolved Copper in Shelter Island YachtBasin, San Diego Bay, dated February 9, 2005. 14. SAMPLING PROTOCOL: Future sampling should be done in accordance with the best current protocols to reduce sample bias regarding low concentrations ofmetals in marine waters. 15. COMPLIANCE MONITORING: Water quality monitoring will berequired to assess compliance in SIYB with the copper load and wasteloadreductions specified in this TMDL and with the waterquality objectives for copper. 16. COMPLIANCE SCHEDULE: Copper load and wasteload reductions are required over a 17-yearstagedcompliance schedule period. ·The first stage consists of an initial 2-year orientation period during which no copperload and wasteloadreductions are required. The subsequent 15-yearreduction period is comprised ofthree stages during which incremental copperload and wasteload reductions are required. 17. SCIENTIFIC PEER REVIEW: The scientific basis ofthis TNIDL has undergone external peerreview pursuant to Health and Safety Code section 57004. The Regional Boardhas considered andresponded to all comments submitted by the peerreview panel. 18. STAKEHOLDER PARTICIPATION: Interested persons and the public have had reasonable opportunity to participate in review ofthe amendment to the Basin Plan. A CaliforniaEnvironmental Quality Act (CEQA) scoping meeting was held on March 19, 2003. Efforts to solicit public review and comment included three public workshops held ·between May 2000 and December 2003; a public review and commentperiod of90 days preceding and following the Regional Boardpublic hearing; a second public comment period of 30 days following the release ofthe revised TMDLTechnical Report dated October 14, 2004; and written responses from the Regional Board to oral and written comments received from the public. 19. ECONOMIC ANALYSIS: The Regional Board has considered the costs ofreasonably foreseeable methods ofcompliance with the load and wasteloadreductions specified in this TMDL.

420. 

### CEQA REQUIREl\ffiNTS: The basin planning process has been certified as functionally equivalent to the CEQArequirements for preparing environmental documents and is, therefore, exempt from those requirements (Public Resources Code section 21000 et seq.). The required environmental documentation (Basin Plan amendment, technical report, and environri:lental checklist) has been prepared. The Regional Boardfinds that the analysis contained in theTMDL Technical Report, the CEQA checklist, and the responses to comments comply with the requirements ofthe State Board's certifiedregulatory CEQA process, as set forth in the California Code of Regulations, title 23, section 3375 et seq. Furthermore, the Regional Board finds that the analysis fulfills the Regional Board's obligations attendant with the adoption ofregulations "requiring the installation ofpollution control equipment, or a performance standard treatment orrequirement", as set forth in section 21159 ofthe Public Resources Code. 21. DEMINIMIS ENVIRONMENTAL EFFECTS: This Basin Plan amendment will result in no potential for adverse effect, either individually orcumulatively, on wildlife. 22. PUBLIC NOTICE: The Regional Board has notified all known interested parties and the public ofits intent to consider adoption ofthis Basin Plan amendment in accordance with 

## ewe section 13244. 23. PUBLIC HEARING: The Regional Board has, at a public meeting on December 10, 2003, held a public hearing and heard and considered all cqmments pertaining to this Basin Plan amendment. 24. BASIN PLAN ORGANIZATION: Basin Plan Chapter4, Implementation needs to be reorganized to create a subsection in which to include the Shelter Island Yacht Basin Dissolved CopperTMDL, and the Chollas CreekDiazinon TMDL Basin Plan amendments, and any future TMDL Basin Plan amendments. NOW, THEREFORE, BEIT RESOLVED that 1. AMENDMENT ADOPTION: TheRegional Board hereby adopts this amendment to the Basin Plan to incorporate the Shelter Island Yacht Basin Dissolved Copper TMDL, and to reorganize Chapter4 as set forth in Attachment A hereto. 2. TECHNICAL REPORTAPPROVAL: The Regional Board hereby approves the Technical Report for Total Maximum Daily Load forDissolved CopperIn ShelterIsland Yacht Basin, San Diego Bay, 

### dated February 9, 2005. 3. CERTIFICATE OFFEEEXE:MPTION: TheExecutive Officer is authorized to sign a Certificate ofFee Exemption. 4. AGENCY APPROVALS: The Executive Officer is directed to submit this Basin Plan amendment to the State Board in accordance with CWC section 13245. The Regional Board requests that the State Board approve the Basin Plan amendment and forward it

### to Office of



### 5Administrative Law (OAL) and the USEPA for approval. 5. 

### NON-SUBSTAI'I'TIVE CORRECTIONS: If, during the approval process for this amendment, the State Board or OALdetermines that minor, non-substantive corrections to the language ofthe amendment are needed for clarity orconsistency, the Executive Officer may make such changes, and shall inform the Regional Board ofany such changes. I. John 

### H. Robertus, Executive Officer, do hereby certify theforegoing is afull, true and correct copy of a Resolution adoptedby the California Regional Water Quality Control Board, San Diego Region, on February 9, 2005. 

# G:rLIf-

# 1{/J!::Ij

.

.JdHN H. ROBEiTUS :k"xecutive Officer



### 6

### ATTACHMENTA TO RESOLUTION NO. R9-2005-0019 AMENDMENT TOTHE WATER QUALITY CONTROLPLANFORTHE SAN DIEGO REGION TOINCORPORATE A TOTAL MAXIMUM DAILY LOAD FORDISSOLVED COPPERIN SHELTERISLAND YACHT BASIN, SAN DIEGO BAY This Basin Plan amendment establishes a Total MaximumDaily Load (TMDL) and associated load and wasteload reductions for dissolved copperin the Shelter Island Yacht Basin portion of San Diego Bay. This amendment includes a program to implement the TMDL and monitorits effectiveness. This amendment also reorganizes portions of Chapter 4 ofthe Basin Plan dealing with TMDLs and creates a new subsection in which to include the Chollas CreekDiazinon TMDL, the Shelter Island Yacht Basin Dissolved CopperTMDL, and any future TMDL Basin Plan amendments. Chapters 2, 3, and 4 ofthe Basin Plan are amended as follows: 

### Chapter 2. Beneficial Uses Table 2-3. Beneficial Uses ofCoastal Waters, San Diego Bay Add the following footnote 3 to San Diego Bay

3The ShelterIsland Yacht Basin portion ofSan Diego Bay is designated as an impaired water body for dissolved copper pursuant to Clean**'~'ater** Act section 303(d). A Total Maximum Daily Load (TMDL) has been adopted to address this impairment. See Chapter 3, Water Quality Objectives for Pesticides, Toxicity and Toxic Pollutants and Chapter4, Total Maximum Daily Loads. 

### Chapter 3, Water Qualitv Objectives Inland Surface Waters, Enclosed Bays and Estuaries, CoastalLagoons, and Ground Waters Water Quality Objectivesfor Pesticides: Add a third paragraph as follows: The Shelter Island Yacht Basin portion ofSan Diego Bay is designated as an impaired waterbody for dissolved copper pursuant to Clean Water Act section 303(d). A Total MaximumDaily Load (TMDL) has been adopted to address this impairment. See Chapters 2, Table 2-3, Beneficial Uses ofCoastal Waters, San Diego Bay, Footnote 3 and Chapter4, Total MaximumDaily Loads.
Water Quality Objectivesfor Toxicity: Add a fourth paragraph as follows: The ShelterIsland Yacht Basin portion of San Diego Bayis designated as an impaired water body for dissolved copper pursuant to Clean Water Act section 303(d). A Total MaximumDaily Load (TMDL) has been adopted to address thisimpairment. See Chapters 2, Table 2-3, Beneficial Uses ofCoastal Waters, San Diego Bay, Footnote 3 and Chapter4, TotalMaximumDaily Loads. 

### Water Quality Objectivesfor Toxic Pollutants: Add a second paragraph as follows: The Shelter Island Yacht Basin portion ofSan Diego Bay is designated as an impaired water body for dissolved copperpursuant to Clean Water Act section 303(d). A Total Maximum Daily Load (TNIDL) has been adopted to address this impairment. See Chapters 2, Table 2-3, Beneficial Uses ofCoastal Waters, San Diego Bay, Footnote 3 and Chapter4, Total MaximumDaily Loads. Chapter4, Implementation Change the second order subsection 

### "California Water QualityAssessment(WQA)" to a first order section by removing it from and placing 

### it before the section 

### "OtherPrograms." Change the second order subsection 

### "California's 303(d) Process" to a first order section by removing it from the section "OtherPrograms" and placing it after the section 

### "California Water QualityAssessment(WQA)." Change the name ofthe section 

### "California's 303(d) Process" to 

### "Clean WaterActSection303(d) Requirements forImpaired Waterbodies." Move the sixth paragraph (which begins with "The 303(d) list ofWQLS

...") to the position after the first sentence in the secondparagraph. Begin a new paragraph with the second sentence of paragraph 2 (which begins with "Section 303(d) requires

...").

Remove 

### "(TMDL)" from the title ofthe subsection 

### "TotalMaximum Daily Load (TMDL)for Diazinon, Chollas Creek Watershed, San Diego County" and move this subsection from 

### "Other Programs'' into the section 

### "Clean WaterActSection 303(d) Requirements forImpaired W

aterbodies." After the subsection on the Chollas Creek Diazinon TNIDL add the following subsection: 

### Total Maximum Daily Load forDissolved Copper, ShelterIsland YachtBasin, San Diego Bay On February 9, 2005, the Regional Board adopted Resolution No. R9-2005-0019, A Resolution Adopting anAmendment to the Water Quality Control Planfor the San Diego Region to Incorporate a Total Maximum Daily Load for Dissolved Copper in the ShelterIsland Yacht Basin, San Diego Bay. TheTNIDL Basin Plan Amendment was subsequently approvedby the State Water Resources Control Board on [Insert Date], the Office ofAdministrative Law on [Insert Date], and the United States Environmental Protection Agency on [Insert Date]. The TMDLis described in the Total Maximum Daily Load forDissolved Copper in ShelterIsland Yacht Basin, San Diego Bay, Technical Report datedFebruary 9, 2005.

2

### Problem Statement Dissolved copper levels in ShelterIsland Yacht Basin (SIYB) waters violate water quality objectives for copper, toxicity, and pesticides. Dissolved copper concentrations in SIYB threaten and impairthe designated beneficial uses ofmarine habitat (MAR), and wildlife habitat (W1LD). 

### Numeric Target The TMDL Numeric Targets for copper, toxicity and pesticides are set equal to the numeric water quality objectives for dissolved copper as defined in the California Toxics Rule (CTR) and shown below. 

### Table 4-10. TMDL Numeric Targets. Exposure Water Quality Objective* Numeric Target* Continuous orChronic 3.1 Jlg/L**ofcopper (Cu) 3.1 Jlg/L**ofCu (4 day avera e) Maximum or Acute 4.8 )lg/L** ofCu 4.8 )lg/L** ofCu (1 hour averacre) * Concentrations should not beexceeded more than once every three years. ** micrograms/liter ()lgiL) Ifthe water quality objectives for dissolved copperin SIYB are modified in the future, as in the case of a site-specific objective, then the numeric targets will be set equal to the new water quality objectives. 

### SourceAnalvsis Approximately 98 percent of all copper loading to SIYB is attributable to copper-based antifouling paints applied to the hulls ofrecreational boats. The passive leaching ofcopper from antifouling paint is 93 percent ofthe total loading. Theremaining five percent oftotal copper loading results from underwater hull cleaning operations in SIYB. 

### Table 4-11. Summary of Dissolved Copper Sources to SIYB. Source Mass Load (kg/year) Percent Contribution (% Cu) Passive Leaching 2,000 93 Hull Cleaning 100 5 Urban Runoff 30 ] Background 30 I Direct Atmospheric 3 <1 Deposition Sediment 0 0 Combined Sources 2,163 100


### Total MaximumDaily Load TheTMDL or loading capacity for dissolved copper discharges into SIYB is 1.6 kilograms/day (kg/day) or 567 kilograms/year (kg/year).



### 3

### Margin ofSafety The TlviDL includes an explicit and implicit margin of safety (MOS). Ten percent ofthe loading capacity was reserved as an explicit MOS and calculated to be 57 kg/year. The implicit MOS was incorporated into the TlviDL source analysis through numerous conservative assumptions. 

### Allocations and Reductions A 76 percent overall reduction ofresidual copper loading to SIYB is required to meet the TMDL of567 kg/year as shown in the table below. The assigned allocations from each source translate into a percentreduction ofdissolved copper from current loading. Loading due to passive leaching must be reduced by 81 percent from current loading. Loading due to underwater hull cleaning mustbe reduced by 28 percent from current loading. From an overall perspective, passive leaching loading must be reduced by 75 percent from the combinedtotal loading ofall sources to SIYB. Underwater hull cleaning loading must be reduced by one percent from the combined total loading ofall sources to SIYB. 

### Table 4-12. TMDL andAllocation Summary. Source Current Percent Allocation Percent Percent Load Contribution (kg/year of Reduction Reduction (kg/year (% Cu) Cu) From Current from Total ofCu) SourceLoad Loading to (%) SIYB (%) PassiveLeaching 2,000 93 375 81 75 Hull Cleaning 100 5 72 I 28 1 Urban Runoff 30 1 30 0 0 Background 30 1 30 0 0 Direct 3 <1 3 0 0 Atmospheric Deposition Sediment 0 0 0 0 0 CurrentMass 2,163 100 0 Load Mar!lin ofSafetv 57 0 TMDL 567 0 Total Load 76 76 Reduction 

### Recalculations ifWater Quality Objectives Change Ifthe waterquality objectives for dissolved copper in SIYB are changed in the future, then the MOS, TlviDL and allocations will be recalculated using the method shown in Appendix D ofthe Basin Plan.

4

### TMDL Implementation Plan
The T:t\IDL will be implemented as follows:

• The Regional Board will coordinate with governmental agencies having legal authority over the use ofcopper-based antifouling paints to protect water quality from the adverse effects of copper-based antifouling paints in SIYB; and

• The Regional Board will regulate discharges ofcopper to SIYB through the issuance of Waste Discharge Requirments (WDRs), Waivers ofWDRs (waivers), or adoption ofWaste Discharge Prohibitions. WDRs could build upon pollution control programs developed by discharger organizations orthe Port. Likewise, waivers orprohibitions could be conditioned on implementation ofpollution control programs through third party agreements between the Regional Board and discharger organizations, and/or other agencies.

• The Regional Board will amend OrderNo. 2001-01, "WasteDischarge Requirements for Discharges ofUrban Runofffrom the Municipal Separate Storm/Sewer Systems" to require that discharges ofcopperinto SIYB waters via the City's municipal separate storm/sewer system not exceed a 30 mg/kg wasteload for copper. The dischargers will be required to monitor SIYB waters and provide monitoring reports to the Regional Board for the purpose ofassessing the effectiveness ofthe alternatives implemented. 

### Compliance Schedule Copper load and wasteload reductions are required over a 17-year staged compliance schedule period. The first stage consists ofan initial 2-year orientation period during which no copper load reductions are required. The subsequent 15-yearreduction period is comprised ofthree stages during which incremental copperload and wasteload reductions are required as shown below. 

### Table 4-13. Interim Loading TargetsforAttainment of the TMDL. Stage Time Percent Reduction Reduction to be Estimated Interim Period from Current Attained by TargetLoading Estimated Loading End ofYear (kg/year ofdissolved Cu) Stage 1 Years 1-2 0% N/A N/A Stage 2 Years 2-7 10% 7 1,900 Stage 3 Years 7-12 40% 12 1,300 Stage4 Years 12-17 76% 17 567 At the end ofthe Basin Plan, add the following Appendix D:



### 5

### APPENDIXD METHOD FOR RECALCULATIONOF THE TOTAL MAXIMUMDAILYLOAD FOR DISSOLVED COPPER IN THE SHELTERISLAND YACHTBASIN, SANDIEGOBAY This appendix describes the method for recalculating the Shelter Island Yacht Basin TMDL for dissolved copperifthe water quality objectives for dissolved copper are modified in the future. 

### Numeric Target The numeric targets are set equal to the new water quality objectives. 

### Margin ofSafetv The explicitmargin of safety (MOS) equals ten percent ofthe loading capacity. The equation to calculate the loading capacity is given below. Total MaximumDaily Load The TJ\.IDL or loading capacity is recalculated using equations 1through 4 below. The loading capacity is recalculated according to equation 1 below:

where 

### C1 = average background concentration ofcopper measured in the area ofSan Diego Bay adjacent to SIYB, expressed as total copper, (0.05**~-tg!L)** C

2 =averagetarget concentration for copperin the SIYB (expressed as total copper) when the maximum concentration ofcopperin SIYB is equal to or less than the numeric target (mass/volume) K = dispersion coefficient calculated from salinity measurements and mixing length approximation (15.3 m2 /sec) Ac =cross-sectional area ofentrance to SIYB (1,000 m2) As =surface area ofSIYB (740,000 m2) Ax 

# = average mixing length between SIYB and adjacent area; estimated distancebetween the endpoints for 

## sl and

## s2 (2,000 m) V2 =volume ofSIYB (31,000,000 m3) e 

### = evaporation rate (0.43 em/day) k

1 =rate oftotal copperloss to sediment (7%/day) Rs =loading capacity, expressed as total copper (mass/time); Rs is calculatediteratively to find the maximum possible value that does not cause C2 to exceed the numeric target.



### 6The dispersion coefficient K is calculated using equation 2 below:

where S1, S2 = salinity data obtained in SIYB and San Diego Bay adjoining SIYB (33.62 practical salinity units (psu) and 33.46 psu, respectively). The average target concentration, C2, mustbe lower than the numeric target concentration to ensure that the loading capacity will not cause an exceedance ofthe numeric target anywhere in SIYB. Cz is calculated by multiplying the numeric target for chronic exposure by the ratio ofthe average measured concentration ofcopperin SIYB to the maximum measured concentration as expressed in equation 

### 3 below: (3) Cz =numeric target [average measured concentration/maximum measured concentration] Or, C2 =numeric target* [5.45 J.tg/L I 8 J.tg/L] To convert C2 from dissolved copper concentration to total copper concentration, the number calculated from equation 3 is multiplied by the ratio ofdissolved copperto total copperin seawater. If site-specific data are not available, the ratio of0.83 can be used. This is the USEPA's conversion factor for saltwater acute criteria. 1 Finally, the TMDLis calculated according to equation 4 below: (4) TMDL=Rs-MOS 

### Allocations Equation 5 is used to determine the new allocation for passive leaching. In equation 5, the only variable is the allocation for passive leaching (Ap), while the other source allocations are constants. The allocation for hull cleaning remains the same, since it was based on the assumption that all ofthe divers will use Management Practices (MPs) to clean boat hulls that have copperbottom paints. Allocations for the other sources, namely urban runoff, background and sediment will not be recalculatedbecause these sources ofcopper are insignificant. (5) TMDL = WasteloadAllocation+ Load Allocations+ MOS

where: TMDL=Au +Ap+Ah +As+ Ab +Aa+MOS

Au = allocation for urban runoff= 30 kg/year Ap =allocation for passiveleaching Ah = allocation for hull cleaning = 72 kg/year

1USEPA. 2000. Water Quality Standards; EstablishmentofNumeric Criteria for Priority Toxic Pollutants for the State ofCalifornia; Rule. 40 CFR Part 131. May 18, 2000.

7As= allocation for sediment= load from sediment= 0 kg/year Ab 

# = allocation for background 

### = load from background 

### = 30 kg/year Aa

# =allocation for direct atmospheric deposition 

# = loadfrom direct atmospheric deposition 

### =3 kg/year.

8