CENTRAL COAST REGIONAL WATER PROJECT. DeepWater Desal, LLC. Project Description. Prepared For: The California Public Utilities Commission.

Transcription

1 CENTRAL COAST REGIONAL WATER PROJECT DeepWater Desal, LLC Project Description Prepared For: The California Public Utilities Commission May 1, 2013 Appendices

2 Appendix A Assessor s Parcel Maps for Tank Farm Parcel and the Moss Landing Power Plant

3 Figure A-1. Assessor s map showing the Tank Farm Parcel (APN ).

4 Figure A-2. Assessor s map showing the Moss Landing Power Plant (APN ).

5 Appendix B Design Projections for the SWRO

6 Hydranautics Membrane Solutions Design Software, v /18/2013 BASIC DESIGN WITH Pressure/Work Exchanger RO program licensed to: Calculation created by: JAD Project name: DWD Permeate flow: gpm Raw water flow: gpm Feed pressure: psi Permeate recovery: 45.0 % Feedwater Temperature: 29.0 C(84F) Feed water ph: 8.20 Element age: 0.0 years Chem dose, ppm (100%): 0.0 NaOH Flux decline % per year: 7.0 Fouling Factor 1.00 Salt passage increase, %/yr: 10.0 Average flux rate: 9.2 gfd Feed type: Seawater - open intake Stage Perm. Flow/Vessel Flux Beta Conc.&Throt. Element Elem. Array Flow Feed Conc Pressures Type No. gpm gpm gpm gfd psi psi SWC4B MAX x7 CALCULATION OF POWER REQUIREMENT Main Pump ERD Boost Feed pressure, psi Concentrate pressure, psi HP Pump flow:, gpm Permeate flow,gpm H.P. Differential of Pressure/Work 14.5 Exchanger, psi Recovery ratio, % 45.0 Pump efficiency, % Motor efficiency, % ERT efficiency, % 0.0 ERT backpressure, psi 0.0 Power/Stage/Pass, kw Pumping energy, kwhr/kgal Pumping power, kw Recovered power, kw 0.0 H.P. Differential of Pressure/Work Exchanger: 14.5 psi Pressure/Work Exchanger Leakage: 2 % Pressure/Work Exchanger Pump Boost Pressure: 37.9 psi Volumetric Mixing: 6 % Product performance calculations are based on nominal element performance when operated on a feed water of acceptable quality. The results shown on the printouts produced by this program are estimates of product performance. No guarantee of product or system performance is expressed or implied unless provided in a separate warranty statement signed by an authorized Hydranautics representative. Calculations for chemical consumption are provided for convenience and are based on various assumptions concerning water quality and composition. As the actual amount of chemical needed for ph adjustment is feedwater dependent and not membrane dependent, Hydranautics does not warrant chemical consumption. If a product or system warranty is required, please contact your Hydranautics representative. Non-standard or extended warranties may result in different pricing than previously quoted. (8/60)

7 Hydranautics Membrane Solutions Design Software, v /18/2013 BASIC DESIGN WITH Pressure/Work Exchanger RO program licensed to: Calculation created by: JAD Project name: DWD Permeate flow: gpm Raw water flow: gpm Feed pressure: psi Permeate recovery: 45.0 % Feedwater Temperature: 29.0 C(84F) Feed water ph: 8.20 Element age: 3.0 years Chem dose, ppm (100%): 0.0 NaOH Flux decline % per year: 7.0 Fouling Factor 0.80 Salt passage increase, %/yr: 10.0 Average flux rate: 9.2 gfd Feed type: Seawater - open intake Stage Perm. Flow/Vessel Flux Beta Conc.&Throt. Element Elem. Array Flow Feed Conc Pressures Type No. gpm gpm gpm gfd psi psi SWC4B MAX x7 CALCULATION OF POWER REQUIREMENT Main Pump ERD Boost Feed pressure, psi Concentrate pressure, psi HP Pump flow:, gpm Permeate flow,gpm H.P. Differential of Pressure/Work 14.5 Exchanger, psi Recovery ratio, % 45.0 Pump efficiency, % Motor efficiency, % ERT efficiency, % 0.0 ERT backpressure, psi 0.0 Power/Stage/Pass, kw Pumping energy, kwhr/kgal Pumping power, kw Recovered power, kw 0.0 H.P. Differential of Pressure/Work Exchanger: 14.5 psi Pressure/Work Exchanger Leakage: 2 % Pressure/Work Exchanger Pump Boost Pressure: 38.3 psi Volumetric Mixing: 6 % Product performance calculations are based on nominal element performance when operated on a feed water of acceptable quality. The results shown on the printouts produced by this program are estimates of product performance. No guarantee of product or system performance is expressed or implied unless provided in a separate warranty statement signed by an authorized Hydranautics representative. Calculations for chemical consumption are provided for convenience and are based on various assumptions concerning water quality and composition. As the actual amount of chemical needed for ph adjustment is feedwater dependent and not membrane dependent, Hydranautics does not warrant chemical consumption. If a product or system warranty is required, please contact your Hydranautics representative. Non-standard or extended warranties may result in different pricing than previously quoted. (8/60)

8 Hydranautics Membrane Solutions Design Software, v /18/2013 BASIC DESIGN WITH Pressure/Work Exchanger RO program licensed to: Calculation created by: JAD Project name: DWD Permeate flow: gpm HP Pump flow: gpm Raw water flow: gpm Feed pressure: psi Permeate recovery: 45.0 % Feedwater Temperature: 29.0 C(84F) Feed water ph: 8.20 Element age: 0.0 years Chem dose, ppm (100%): 0.0 NaOH Flux decline % per year: 7.0 Fouling Factor 1.00 Salt passage increase, %/yr: 10.0 Average flux rate: 9.2 gfd Feed type: Seawater - open intake Stage Perm. Flow/Vessel Flux Beta Conc.&Throt. Element Elem. Array Flow Feed Conc Pressures Type No. gpm gpm gpm gfd psi psi SWC4B MAX x7 Raw water Adjusted Water Feed water Permeate Concentrate ERD Reject Ion mg/l mg/l mg/l mg/l mg/l mg/l Ca Mg Na K NH Ba Sr CO HCO SO Cl F NO B SiO CO TDS ph Raw water Feed water Concentrate CaSO4 / Ksp * 100: 17% 17% 36% SrSO4 / Ksp * 100: 31% 33% 68% BaSO4 / Ksp * 100: 11% 12% 23% SiO2 saturation: 2% 2% 4% Langelier Saturation Index Stiff & Davis Saturation Index Ionic strength Osmotic pressure psi psi psi H.P. Differential of Pressure/Work Exchanger 14.5 psi Pressure/Work Exchanger Leakage: 2 % Pressure/Work Exchanger Boost Pressure 37.9 psi Volumetric Mixing 6 % Product performance calculations are based on nominal element performance when operated on a feed water of acceptable quality. The results shown on the printouts produced by this program are estimates of product performance. No guarantee of product or system performance is expressed or implied unless provided in a separate warranty statement signed by an authorized Hydranautics representative. Calculations for chemical consumption are provided for convenience and are based on various assumptions concerning water quality and composition. As the actual amount of chemical needed for ph adjustment is feedwater dependent and not membrane dependent, Hydranautics does not warrant chemical consumption. If a product or system warranty is required, please contact your Hydranautics representative. Non-standard or extended warranties may result in different pricing than previously quoted. (8/60)

9 Hydranautics Membrane Solutions Design Software, v /18/2013 BASIC DESIGN WITH Pressure/Work Exchanger RO program licensed to: Calculation created by: JAD Project name: DWD Permeate flow: gpm HP Pump flow: gpm Raw water flow: gpm Feed pressure: psi Permeate recovery: 45.0 % Feedwater Temperature: 29.0 C(84F) Feed water ph: 8.20 Element age: 0.0 years Chem dose, ppm (100%): 0.0 NaOH Flux decline % per year: 7.0 Fouling Factor 1.00 Salt passage increase, %/yr: 10.0 Average flux rate: 9.2 gfd Feed type: Seawater - open intake Stage Perm. Flow/Vessel Flux Beta Conc.&Throt. Element Elem. Array Flow Feed Conc Pressures Type No. gpm gpm gpm gfd psi psi SWC4B MAX x7 Stg Elem Feed Pres Perm Perm Beta Perm Conc Cumulative Perm Ion levels no. pres drop flow Flux sal osm Ca Mg Cl B SiO2 psi psi gpm gfd TDS pres Stage NDP psi Product performance calculations are based on nominal element performance when operated on a feed water of acceptable quality. The results shown on the printouts produced by this program are estimates of product performance. No guarantee of product or system performance is expressed or implied unless provided in a separate warranty statement signed by an authorized Hydranautics representative. Calculations for chemical consumption are provided for convenience and are based on various assumptions concerning water quality and composition. As the actual amount of chemical needed for ph adjustment is feedwater dependent and not membrane dependent, Hydranautics does not warrant chemical consumption. If a product or system warranty is required, please contact your Hydranautics representative. Non-standard or extended warranties may result in different pricing than previously quoted. (8/60)

10 Hydranautics Membrane Solutions Design Software, v /18/2013 BASIC DESIGN WITH Pressure/Work Exchanger RO program licensed to: Calculation created by: JAD Project name: DWD Permeate flow: gpm HP Pump flow: gpm Raw water flow: gpm Feed pressure: psi Permeate recovery: 45.0 % Feedwater Temperature: 29.0 C(84F) Feed water ph: 8.20 Element age: 0.0 years Chem dose, ppm (100%): 0.0 NaOH Flux decline % per year: 7.0 Fouling Factor 1.00 Salt passage increase, %/yr: 10.0 Average flux rate: 9.2 gfd Feed type: Seawater - open intake ********************************************************************* **** THE FOLLOWING PARAMETERS EXCEED RECOMMENDED DESIGN LIMITS: *** ********************************************************************* Concentrate Langelier Saturation Index too high (1.84) The following are recommended general guidelines for designing a reverse osmosis system using Hydranautics membrane elements. Please consult Hydranautics for specific recommendations for operation beyond the specified guidelines. Feed and Concentrate flow rate limits Element diameter Maximum feed flow rate Minimum concentrate rate 8.0 inches 75 gpm (283.9 lpm) 12 gpm (45.4 lpm) 8.0 inches(full Fit) 75 gpm (283.9 lpm) 30 gpm (113.6 lpm) Concentrate polarization factor (beta) should not exceed 1.2 for standard elements Saturation limits for sparingly soluble salts in concentrate Soluble salt Saturation BaSO4 6000% CaSO4 230% SrSO4 800% SiO2 100% Langelier Saturation Index for concentrate should not exceed 1.8 The above saturation limits only apply when using effective scale inhibitor. Without scale inhibitor, concentrate saturation should not exceed 100%. Product performance calculations are based on nominal element performance when operated on a feed water of acceptable quality. The results shown on the printouts produced by this program are estimates of product performance. No guarantee of product or system performance is expressed or implied unless provided in a separate warranty statement signed by an authorized Hydranautics representative. Calculations for chemical consumption are provided for convenience and are based on various assumptions concerning water quality and composition. As the actual amount of chemical needed for ph adjustment is feedwater dependent and not membrane dependent, Hydranautics does not warrant chemical consumption. If a product or system warranty is required, please contact your Hydranautics representative. Non-standard or extended warranties may result in different pricing than previously quoted. (8/60)

11 Hydranautics Membrane Solutions Design Software, v /18/2013 BASIC DESIGN WITH Pressure/Work Exchanger RO program licensed to: Calculation created by: JAD Project name: DWD Permeate flow: gpm HP Pump flow: gpm Raw water flow: gpm Feed pressure: psi Permeate recovery: 45.0 % Feedwater Temperature: 29.0 C(84F) Feed water ph: 8.20 Element age: 3.0 years Chem dose, ppm (100%): 0.0 NaOH Flux decline % per year: 7.0 Fouling Factor 0.80 Salt passage increase, %/yr: 10.0 Average flux rate: 9.2 gfd Feed type: Seawater - open intake Stage Perm. Flow/Vessel Flux Beta Conc.&Throt. Element Elem. Array Flow Feed Conc Pressures Type No. gpm gpm gpm gfd psi psi SWC4B MAX x7 Raw water Adjusted Water Feed water Permeate Concentrate ERD Reject Ion mg/l mg/l mg/l mg/l mg/l mg/l Ca Mg Na K NH Ba Sr CO HCO SO Cl F NO B SiO CO TDS ph Raw water Feed water Concentrate CaSO4 / Ksp * 100: 17% 17% 36% SrSO4 / Ksp * 100: 31% 33% 68% BaSO4 / Ksp * 100: 11% 12% 23% SiO2 saturation: 2% 2% 4% Langelier Saturation Index Stiff & Davis Saturation Index Ionic strength Osmotic pressure psi psi psi H.P. Differential of Pressure/Work Exchanger 14.5 psi Pressure/Work Exchanger Leakage: 2 % Pressure/Work Exchanger Boost Pressure 38.3 psi Volumetric Mixing 6 % Product performance calculations are based on nominal element performance when operated on a feed water of acceptable quality. The results shown on the printouts produced by this program are estimates of product performance. No guarantee of product or system performance is expressed or implied unless provided in a separate warranty statement signed by an authorized Hydranautics representative. Calculations for chemical consumption are provided for convenience and are based on various assumptions concerning water quality and composition. As the actual amount of chemical needed for ph adjustment is feedwater dependent and not membrane dependent, Hydranautics does not warrant chemical consumption. If a product or system warranty is required, please contact your Hydranautics representative. Non-standard or extended warranties may result in different pricing than previously quoted. (8/60)

12 Hydranautics Membrane Solutions Design Software, v /18/2013 BASIC DESIGN WITH Pressure/Work Exchanger RO program licensed to: Calculation created by: JAD Project name: DWD Permeate flow: gpm HP Pump flow: gpm Raw water flow: gpm Feed pressure: psi Permeate recovery: 45.0 % Feedwater Temperature: 29.0 C(84F) Feed water ph: 8.20 Element age: 3.0 years Chem dose, ppm (100%): 0.0 NaOH Flux decline % per year: 7.0 Fouling Factor 0.80 Salt passage increase, %/yr: 10.0 Average flux rate: 9.2 gfd Feed type: Seawater - open intake Stage Perm. Flow/Vessel Flux Beta Conc.&Throt. Element Elem. Array Flow Feed Conc Pressures Type No. gpm gpm gpm gfd psi psi SWC4B MAX x7 Stg Elem Feed Pres Perm Perm Beta Perm Conc Cumulative Perm Ion levels no. pres drop flow Flux sal osm Ca Mg Cl B SiO2 psi psi gpm gfd TDS pres Stage NDP psi Product performance calculations are based on nominal element performance when operated on a feed water of acceptable quality. The results shown on the printouts produced by this program are estimates of product performance. No guarantee of product or system performance is expressed or implied unless provided in a separate warranty statement signed by an authorized Hydranautics representative. Calculations for chemical consumption are provided for convenience and are based on various assumptions concerning water quality and composition. As the actual amount of chemical needed for ph adjustment is feedwater dependent and not membrane dependent, Hydranautics does not warrant chemical consumption. If a product or system warranty is required, please contact your Hydranautics representative. Non-standard or extended warranties may result in different pricing than previously quoted. (8/60)

13 Hydranautics Membrane Solutions Design Software, v /18/2013 BASIC DESIGN WITH Pressure/Work Exchanger RO program licensed to: Calculation created by: JAD Project name: DWD Permeate flow: gpm HP Pump flow: gpm Raw water flow: gpm Feed pressure: psi Permeate recovery: 45.0 % Feedwater Temperature: 29.0 C(84F) Feed water ph: 8.20 Element age: 3.0 years Chem dose, ppm (100%): 0.0 NaOH Flux decline % per year: 7.0 Fouling Factor 0.80 Salt passage increase, %/yr: 10.0 Average flux rate: 9.2 gfd Feed type: Seawater - open intake ********************************************************************* **** THE FOLLOWING PARAMETERS EXCEED RECOMMENDED DESIGN LIMITS: *** ********************************************************************* Concentrate Langelier Saturation Index too high (1.83) The following are recommended general guidelines for designing a reverse osmosis system using Hydranautics membrane elements. Please consult Hydranautics for specific recommendations for operation beyond the specified guidelines. Feed and Concentrate flow rate limits Element diameter Maximum feed flow rate Minimum concentrate rate 8.0 inches 75 gpm (283.9 lpm) 12 gpm (45.4 lpm) 8.0 inches(full Fit) 75 gpm (283.9 lpm) 30 gpm (113.6 lpm) Concentrate polarization factor (beta) should not exceed 1.2 for standard elements Saturation limits for sparingly soluble salts in concentrate Soluble salt Saturation BaSO4 6000% CaSO4 230% SrSO4 800% SiO2 100% Langelier Saturation Index for concentrate should not exceed 1.8 The above saturation limits only apply when using effective scale inhibitor. Without scale inhibitor, concentrate saturation should not exceed 100%. Product performance calculations are based on nominal element performance when operated on a feed water of acceptable quality. The results shown on the printouts produced by this program are estimates of product performance. No guarantee of product or system performance is expressed or implied unless provided in a separate warranty statement signed by an authorized Hydranautics representative. Calculations for chemical consumption are provided for convenience and are based on various assumptions concerning water quality and composition. As the actual amount of chemical needed for ph adjustment is feedwater dependent and not membrane dependent, Hydranautics does not warrant chemical consumption. If a product or system warranty is required, please contact your Hydranautics representative. Non-standard or extended warranties may result in different pricing than previously quoted. (8/60)

14 Appendix C Preliminary Modeling of Potential Impacts from Operation of a Desalination Facility Ocean Intake

15 DeepWater Desal PRELIMINARY MODELING OF POTENTIAL IMPACTS FROM OPERATION OF A DESALINATION FACILITY OCEAN INTAKE August 22, 2012 Submitted to: Dr. Brent Constanz DeepWater Desal 7532 Sandholdt Rd, Ste 6 Moss Landing, CA Prepared by: Environmental 141 Suburban Rd., Suite A2, San Luis Obispo, CA , FAX:

16 Executive Summary Executive Summary This report presents the results of preliminary modeling to assess the potential for impacts to marine organisms resulting from the intake of seawater by an ocean water desalination plant off Moss Landing, California that is being proposed by DeepWater Desal (DWD) LLC. The objective of this assessment is to develop and test new developments in the analytical approach to the Intake Effects Assessment process and take an early look at the potential entrainment rates based on information about the desalination project which is current at the time of writing. The intake for the proposed DWD facility is expected to have a maximum design capacity of 94,640 m 3 (25,000,000 gal) per day, which equals a rate of 17,360 gpm. This assessment only considers the potential effects of the intake from the entrainment of small planktonic organisms including the eggs and larvae of fishes and invertebrates into the system. Assessment of impingement of larger organisms on the screens at the opening to the intake was not included because the intake will be designed to ensure a through screen velocity of less than 0.5 feet per second (fps), which is the standard used for compliance with California state and U. S. federal policy for power plant ocean intakes. The potential for impacts to fishes and invertebrates due to entrainment at the intake location is evaluated using the Empirical Transport Model (ETM), a modeling approach that has been used on similar ocean intake projects and is the standard approach in California for assessing impacts due to power plant and desalination plant ocean intakes. The modeling approach used for this assessment is the latest refinement in the use of the ETM for assessing the effects of ocean intakes in California. Almost all previous uses of the ETM in California have relied on biological sampling of the entrainment and source waters to estimate the daily proportional entrainment (PE), which is usually calculated for each taxon for each survey as the ratio of the estimated numbers of larvae entrained per day to the larval population estimates within specific volumes of the source water. The PE estimates calculated for many of the previous studies conducted in California showed that the estimates were, in many cases, reasonably close to the volumetric ratio of the intake to the sampled source water used in the PE calculation. This was especially common at intakes located along the open coast in areas with relatively homogeneous habitat such as the nearshore areas off the Huntington Beach Generating Station, an area not dissimilar to many nearshore areas in Monterey Bay. The volumetric approximation of PE is a reasonable approach when the species specific concentrations of larvae at the intake location are approximately equal to the species specific concentrations of larvae in the source water population. This allows the daily mortality to be estimated as the ratio of the volume entrained to the estimated volume of the source water. Although the volumetric approach to PE has not been used in California, this approach was used in the original formulation of the ETM, which was used to estimate impacts due to an intake along a river. Using this approach, the only biological data necessary for the model were the estimates of larval durations for the taxa likely to be subject to entrainment. Due to preliminary nature of this analysis, the availability of existing biological and oceanographic data from the area around the intake location, and the plans for more detailed sampling in the future, the modeling approach used for this assessment was considered appropriate. DeepWater Desal Preliminary Intake Impact Assessment Modeling ES-1

17 Executive Summary The data necessary for the ETM volumetric model include the expected daily volume of the intake 94,640 m 3 (25,000,000 gal) which was based on an intake flow rate of 65.7 m 3 (17,360 gal) per minute and the volumes of the source water, which were estimated separately for each taxon for each month using CODAR data on ocean currents available through Central & Northern California Ocean Observing System (CeNCOOS). Data on surface currents over the entire Monterey Bay and surrounding coastline from CeNCOOS CODAR stations were adjusted to midwater column speeds using data from an ADCP current meter that is also maintained by CeNCOOS and is located just offshore from the intake. The use of CODAR for determining the source water areas potentially affected by entrainment is a substantial improvement over previous assessments in California that relied on point-source data from one or two ADCP current meters. Using the source water estimates derived from the CODAR back-projections and adjusted by a kernel density analysis to eliminate the 5% least frequently occurring cells, the estimated annual mortalities due to entrainment by the proposed DWD intake of a maximum of 94,640 m 3 (25,000,000 gal) per day were very small, approximately 0.20 percent or less, for the four coastal fishes analyzed, reflecting the small intake volume relative to the source water (Table ES-1). The back-projections indicate that the majority of the impacts would be restricted to areas close to shore in the central and northern portions of the bay for northern anchovy and the three other taxa. Table ES-1. Annual mortality estimates (P M ) and average of monthly source water volumes used in ETM modeling for larvae from four fishes found in the nearshore areas of Monterey Bay. Fish Taxon Average Source Volume (km 3 ) Annual PM northern anchovy white croaker blue rockfish KGB rockfish Acknowledgements The information in this report relies heavily on data available through CeNCOOS using the network of instruments deployed by the State of California's Coastal Ocean Currents Monitoring Program (COCMP). The CODAR data was obtained and back-projection processing was completed by Mr. Brian Zelenke. The final content of the report benefited from comments on earlier versions from Dr. Peter Raimondi, University of California, Santa Cruz, and Dr. Jeffrey Paduan at the U. S. Naval Postgraduate School, Monterey, California. DeepWater Desal Preliminary Intake Impact Assessment Modeling ES-2

18 Table of Contents Table of Contents Executive Summary INTRODUCTION MODEL AND DATA METHODS Empirical Transport Model (ETM) Biological Data Used in Modeling Sampling Methods Taxa Selected for Analysis Larval Durations MLPP Source Water Body Calculations Data Sources and Processing CODAR Back-Projections Kernel Density Estimates of Source Area and Volume Total Source Water Body Source Water Volume IMPACT ASSESSMENT ANALYSIS RESULTS Larval Durations Larval Seasonality Impact Assessment Mortality Estimates IMPACT ASSESSMENT DISCUSSION AND CONCLUSIONS FUTURE DIRECTION LITERATURE CITED DeepWater Desal Preliminary Intake Impact Assessment Modeling i

19 List of Tables List of Tables Table 2-1. Collection specifications for source water sampling at MLPP Table 2-2. Average concentrations and number collected of fish taxa at three stations (N1, S1 and Harbor Mouth) during daytime high and low tide sampling from September 1999 through May 2000 for Moss Landing Power Plant (Tenera 2000a) Table 2-3. The distance in km upcoast and downcoast from the intake location of the maximum northerly and southerly extent of CODAR back-projections to 46 days for each corresponding sample month for northern anchovy. These extents are used to delimit the total source water body extent and derive the volume of the source water body (V Si ) for that month for the taxon (also shown) Table 2-4. The distance in km upcoast and downcoast from the intake location of the maximum northerly and southerly extent of CODAR back-projections to days for each corresponding sample month for white croaker. These extents are used to delimit the total source water body extent and derive the volume of the source water body (V Si ) for that month for the taxon (also shown) Table 2-5. The distance in km upcoast and downcoast from the intake location of the maximum northerly and southerly extent of CODAR back-projections to 7.95 days for each corresponding sample month for the KGB rockfish complex. These extents are used to delimit the total source water body extent and derive the volume of the source water body (V Si ) for that month for that taxon (also shown) Table 2-6. The distance in km upcoast and downcoast from the intake location of the maximum northerly and southerly extent of CODAR back-projections to 7.95 days for each corresponding sample month for blue rockfish. These extents are used to delimit the total source water body extent and derive the volume of the source water body (V Si ) for that month for that taxon (also shown) Table 3-1. Statistics of larval fish lengths from samples collected near Moss Landing (white croaker) and near Diablo Canyon Power Plant (rockfish and anchovy). Estimated larval durations are calculations using statistics and literature based growth rates. The estimate for rockfish was used for both blue and KGB rockfish larvae Table 3-2. Mortality estimation (P M ) for northern anchovy eggs and larvae at the intake location based on a planktonic duration of 48.3 d. Source water volumes calculated from kernel density estimates for back-projections from March July and the average monthly upcoast and downcoast excursions of the back-projections. Densities used for weighting mean survival were measured during a study at DCPP (Tenera 2000b). The survivals were calculated as (1-PE) 48.3 d. Survivals with weights (f i ) of zero were not included in the calculation of P M Table 3-3. Mortality estimation (P M ) for white croaker eggs and larvae at the intake location based on a planktonic duration of 17.2 d. Source water volumes calculated from kernel density estimates for back-projections from January June and the average monthly upcoast and downcoast excursions of the back-projections. Densities used for weighting mean survival were measured during a study at DCPP (Tenera 2000b). The survivals were calculated as (1-PE) 17.2 d. Survivals with weights (f i ) of zero were not included in the calculation of P M DeepWater Desal Preliminary Intake Impact Assessment Modeling ii

20 List of Tables Table 3-4. Mortality estimation (P M ) for KGB rockfish complex larvae at intake location based on a larval duration of 7.95 d. Source water volumes calculated from kernel density estimates for backprojections from February July and the average monthly upcoast and downcoast excursions of the back-projections. Densities used for weighting mean survival were measured during a study at DCPP (Tenera 2000b). The survivals were calculated as (1-PE) 7.9 d. Survivals with weights (f i ) of zero were not included in the calculation of P M Table 3-5. Mortality estimation (P M ) for blue rockfish complex larvae at the intake location based on a larval duration of 7.95 d. Source water volumes calculated from kernel density estimates for backprojections from January August and the average monthly upcoast and downcoast excursions of the back-projections. Densities used for weighting mean survival were measured during a study at DCPP (Tenera 2000b). The survivals were calculated as (1-PE) 7.9 d. Survivals with weights (f i ) of zero were not included in the calculation of P M Table 4-1. Annual mortality estimates (P M ) and average of monthly source water volumes used in ETM modeling for the CIQ goby complex larvae which are transported out of the Moss Landing Harbor- Elkhorn Slough and larvae from four fishes found in the nearshore areas of Monterey Bay DeepWater Desal Preliminary Intake Impact Assessment Modeling iii

21 List of Figures List of Figures Figure 1-1. Map showing location of terminus of the intake line previously used to supply fuel oil to the Moss Landing Power Plant Figure 2-1. Location of stations sampled during the MLPP 316b study Figure 2-2. Locations of a) M0 current meter in relation to plankton sampling locations (N1 and S1) and the intake location, and b) close up of plankton sampling locations and the two proposed DWD intakes in relation to nearshore subtidal bathymetry. A potential location for a deepwater intake is also shown Figure 2-3. Ocean surface current vectors measured on October 1, 2010 at 0000 UTC in the Monterey Bay, California region by the CeNCOOS CODAR SeaSonde stations (black triangles). Shown are vectors of both the 6 km (3.7 mile) resolution coverage offshore (left) and the higher 2 km (1.2 mile) resolution coverage closer to the coast, shaded according to their velocity per the color-bar (right).2-10 Figure 2-4. The a) U and b) V components of velocity measured over a representative period (approximately two days) at the surface by CODAR and at depth by the M0 ADCP Figure 2-5. CODAR back-projections scaled to ADCP data from buoy M0 and averaged over the 4-20 m (13 60 ft) depth range for dates ending on a) October 1, b) November 1, c) December 1, 2010, and d) January 1,. The back projections use 30 randomly selected start times on the hour ± 1 day. Each back-projection changes color from blue to green to red to represent the time periods of 0 10 d, d, and d, respectively, for each projection Figure 2-6. CODAR back-projections scaled to ADCP data from buoy M0 and averaged over the 4-20 m (13-60 ft) depth range for dates ending on a) February 1, b) March 1, c) April 1, and d) May 1,. The back projections use 30 randomly selected start times on the hour ± 1 day. Each back-projection changes color from blue to green to red to represent the time periods of 0 10 d, d, and d, respectively, for each projection Figure 2-7. CODAR back-projections scaled to ADCP data from buoy M0 and averaged over the 4-20 m (13-60 ft) depth range for dates ending on a) June 1, b) July 1, c) August 1, and d) September 1,. The back projections use 30 randomly selected start times on the hour ± 1 day. Each backprojection changes color from blue to green to red to represent the time periods of 0 10 d, d, and d, respectively, for each projection Figure 2-8. Total source water body extent for northern anchovy eggs and larvae in Monterey Bay based on kernel density estimation of 46-day back-projections for the five months of February to June. The 300 m depth contour is indicated offshore Figure 2-9. Total source water body extent for white croaker eggs and larvae in Monterey Bay based on kernel density estimation of day back-projections for the six months of January to June. The 300 m depth contour is indicated offshore Figure Total source water body extent for KGB rockfish complex eggs and larvae in Monterey Bay based on kernel density estimation of 7.95-day back-projections for the six months of February to July. The 45 m depth contour is indicated offshore DeepWater Desal Preliminary Intake Impact Assessment Modeling iv

22 List of Figures Figure Total source water body extent for blue rockfish eggs and larvae in Monterey Bay based on kernel density estimation of 7.95 day back-projections for the eight months of January to August. The 90 m depth contour is indicated offshore Figure 3-1. Length frequency analysis for white croaker larvae collected from MLPP studies. Below the percentage frequency is a box plot representing the range of 98 percent of the data values with the mean shown as the small filled circle, and the median, and the 25% and 75% quartiles shown by vertical lines with the width height of the box indicating the percent of the data within the interval.3-3 Figure 3-2. Length frequency analysis for a) northern anchovy and b) rockfish larvae collected from studies off Diablo Canyon Power Plant. The box plots were developed in the same way as those presented in Figure Figure 3-3. Monthly estimated average concentration (#/1,000 m 3 ) of northern anchovy (Engraulis mordax) larvae collected at the DCPP source water stations during the sampling. Data from Tenera (2000b) Figure 3-4. Monthly estimated average concentration (#/1,000 m 3 ) of white croaker (Genyonemus lineatus) larvae collected at the DCPP source water stations during the sampling. Data from Tenera (2000b) Figure 3-5. Monthly estimated average concentration (#/1,000 m3) of the KGB rockfish larval complex collected at the DCPP source water stations during the sampling. Data from Tenera (2000b) Figure 3-6. Monthly estimated average concentration (#/1,000 m 3 ) of blue rockfish larva collected at the DCPP source water stations during the sampling. Data from Tenera (2000b) Figure 4-1 The areal extent of the monthly source water volume (V Si ) in April for a) northern anchovy and b) white croaker. The V Si for each species for April has been superimposed on the total source water body extent to show the remaining area not incorporated into the source water volume for the month of April for these taxa DeepWater Desal Preliminary Intake Impact Assessment Modeling v

23 1.0: Introduction 1.0 Introduction This report presents the results of a preliminary modeling effort to assess the potential for impacts to marine organisms resulting from the intake of seawater by an ocean water desalination plant off Moss Landing, California that is being proposed by DeepWater Desal (DWD) LLC. The potential impacts from the intake will largely be confined to the entrainment of small planktonic organisms including the eggs and larvae of fishes and invertebrates into the system. Impingement of larger organisms on the screens at the opening to the intake is not anticipated to be a problem as the intake will be designed to ensure a velocity of less than 0.5 feet per second (fps), which is the standard used for compliance with state and federal policy for power plant ocean intakes. The potential for impacts to fishes and invertebrates due to entrainment at the proposed intake location will be evaluated using the Empirical Transport Model (ETM) a modeling approach that has been used on similar ocean intake projects and is the standard approach in California for assessing impacts due to power plant and desalination plant ocean intakes (Steinbeck et al 2007). This preliminary modeling effort evaluates the potential effects of operating a 122 cm (48 in.) diameter intake line at a depth of approximately 18 m (60 ft) offshore to the northwest of Moss Landing Harbor in Monterey Bay, California (Figure 1-1). The location of the intake line currently has a 91 cm (36 in.) diameter pipe that was previously used for offloading fuel oil from tankers at a marine terminal to the Moss Landing Power Plant. This pipe will be removed and replaced with the new 122 cm (48 in.) diameter line. For the purposes of this analysis, a daily intake volume of 94,640 m 3 (25,000,000 gal) was used in the modeling, although the final intake volume may be less. The assessment in this report uses a strictly modeling approach using the ETM to estimate the potential for impacts to fish and invertebrates due to entrainment by the intake. The potential for using a strictly modeling approach for intake assessment has been demonstrated in the results of previous studies at locations where the intake is located along the open coast in an area with relatively homogeneous habitat, such as the study at the Huntington Beach Generating Station (MBC and Tenera 2005). The basis of the ETM is an estimate of the daily mortality resulting from entrainment which is typically calculated as the number of larvae entrained proportional to the estimated number at risk in the sampled source water. If the concentrations of larvae for a specific taxon are relatively uniform across the sampled source water body then the assumption can be made that the estimated proportional daily mortality is the ratio of the volume of water entrained to the volume of the sampled source water. This simplifying assumption was used in the original formulation of the ETM which was used to estimate impacts due to an intake along a river (Boreman et al. 1978, Boreman et al. 1981). Although a river is a much simpler system to model because of the generally unidirectional flow of water, the volumetric assumption that larvae are uniformly distributed throughout the source water does not compromise the empirically derived calculation of the source water population extent. Instead it allows for the DeepWater Desal Preliminary Intake Impact Assessment Modeling 1-1

24 1.0: Introduction calculation of proportional mortality without needing to sample additional source water body sites. When the volumetric ratio is used in the ETM as the estimate of daily mortality, the only biological data necessary for the model other than the list of taxa present at the entrainment site, are the estimates of larval duration for each taxa likely to be subject to entrainment, and the seasonal variation in larval abundance (presence/absence) for each taxa. These parameters affect the size of the source water body, and the period over which a taxon is subject to entrainment. The selection of taxa for analysis in this report was based on the results from an earlier study at the Moss Landing Power Plant in 2000 (Tenera 2000a) that included sampling in the nearshore areas outside of Moss Landing Harbor, not far from the proposed intake location. The estimates of larval duration for these taxa were derived from data collected from recent studies along the central coast of California including the studies at Moss Landing. The source water for the modeling was estimated using data on ocean currents available through the Central & Northern California Ocean Observing System (CeNCOOS) using the network of instruments deployed by the State of California's Coastal Ocean Currents Monitoring Program (COCMP). This report presents the methods and data sources used in the assessment in Section 2.0. This includes descriptions of the ETM, summaries of the study and data collected for the Moss Landing Power Plant, and the data used in determining the larval durations used in the modeling. The methods for estimating the source water areas and volumes for the modeling are also presented in Section 2.0. The results of the modeling are presented in Section 3.0 and summarized in Section 4.0. DeepWater Desal Preliminary Intake Impact Assessment Modeling 1-2

25 2.0: Modeling and Data Methods Fuel Line Figure 1-1. Map showing location of terminus of the fuel line previously used to supply fuel oil to the Moss Landing Power Plant. DeepWater Desal Preliminary Intake Impact Assessment Modeling 1-1

26 2.0: Modeling and Data Methods 2.0 Model and Data Methods This section includes descriptions of the Empirical Transport Model (ETM) used in assessing the effects of the intake and the data used in the modeling. The biological data includes data from studies for the Moss Landing Power Plant (Tenera 2000a) used in selecting the fishes used in the assessment, data on the seasonal abundances used in estimating weights for the ETM calculations, and data on larval length and growth used in estimating larval durations for the fishes which were taken from the Moss Landing studies and a study at the Diablo Canyon Power Plant (DCPP) during (Tenera 2000b). The data and methods used to estimate the source water for the ETM are also presented. 2.1 Empirical Transport Model (ETM) The ETM was proposed by the U.S. Fish and Wildlife Service to estimate mortality rates resulting from water withdrawals by power plants (Boreman et al. 1978, and subsequently in Boreman et al. 1981). The ETM provides an estimate of incremental mortality (a conditional estimate of entrainment mortality in absence of other mortality, Ricker 1975) based on estimates of the proportional loss to the source water population represented by entrainment. The conditional mortality is represented as estimates of proportional entrainment (PE) that are calculated for each survey and then expanded to predict regional effects on populations using the ETM, as described below. Variations of this model have been discussed in MacCall et al. (1983) and have been used to assess impacts in the previous studies at California power plants (MacCall et al. 1983, Parker and DeMartini 1989, Tenera 2000a, Tenera 2000b, Steinbeck et al. 2007). The estimate of proportional entrainment (PE) is the central feature of the ETM and is usually calculated for each taxon 1 for each survey (i) as the ratio of the estimated numbers of larvae entrained per day to the larval population estimates for the source water (usually referred to as the sampled source water) as follows: PE i N E i EV i Ei, (1) N V S i S i S i where for each taxon, N E i and N S i are the estimated numbers of larvae entrained ( E ) and in the and are the average sampled source water ( S ) on any given day during survey period i, concentrations of larvae of a taxon from the intake location and the sampled source water population, respectively, for which the ratio will remain constant on any given day during survey period i, and V and V are the estimated volumes of the entrained intake water per day (subject E i S i to the operational flow rate of the intake) and the predicted source water extent respectively in 1 Taxon is used to refer to single species or group of closely related species. Taxa is the plural of taxon. E i S i DeepWater Desal Preliminary Intake Impact Assessment Modeling 2-2

27 2.0: Modeling and Data Methods survey period i. The latter is empirically derived from back-projections of adjusted CODAR water currents and is explained in a later section of this report. As is clear from Equation 1, if the concentrations of larvae of taxa are approximately equal in the intake and source water volumes then those two terms cancel each other out and the PE is reduced to the ratio of the two volumes for each survey period i as follows: PE i VE i. (2) V S i The daily volume of the intake used in the modeling was 94,640 m 3 (25,000,000 gal) which was based on an intake flow rate of m 3 (~17,360 gal) per minute. While a reasonably accurate estimate of the volume of the intake flow can be obtained, estimating the extent of the entire source water for the taxon being evaluated (called the source water body) is more difficult and will vary depending upon oceanographic conditions (mainly water currents) and the period of time that the taxon being analyzed is in the plankton and exposed to entrainment. The volume of the source water was estimated separately for each taxon for each month or survey period i using data on ocean currents available through the Central & Northern California Ocean Observing System (CeNCOOS) consortium of the Coastal Ocean Currents Monitoring Program (COCMP). Data on surface currents over the entire Monterey Bay and surrounding coastline from CeNCOOS CODAR stations were adjusted to midwater column speeds using data from a current meter located just offshore from the intake that is also maintained by CeNCOOS. The methodology used in calculating the source water is provided in more detail in Section 2.3. The taxa of fishes used in the modeling were selected based on data collected from studies for the Moss Landing Power Plant in 2000 (Tenera 2000a). The sampling included collections of fish and invertebrate larvae at two stations outside of Moss Landing Harbor in Monterey Bay and at a location between the breakwaters at the harbor entrance (Figure 2-1). Data were only collected from these three stations for nine of the months during the one year study. The larval durations used in the source water estimates were calculated from data collected during the Moss Landing study and from studies conducted at the Diablo Canyon Power Plant (Tenera 2000b). In order to derive an estimate of the proportion of the source water population at risk from entrainment by the intake for a given taxon the estimate of daily mortality rate (PE) is compounded over the number of days the larvae are potentially exposed to entrainment (d). This duration is determined by the maximum sampled age range 2 of all the larvae for that taxon. While a separate PE estimate was calculated for each survey period (i), the larval duration was derived for each taxon for all sampling periods. Although this averages any potential variation in age demographic that may occur in source water population from period to period, it generally provides a more accurate estimate of the duration of potential entrainment for the larva in the 2 Duration is calculated using published growth rate estimates applied to sampled larval length. The durations is the age range in the sampled population (oldest minus youngest). Further details are provided in Section 3.1 of this report. DeepWater Desal Preliminary Intake Impact Assessment Modeling 2-3

28 2.0: Modeling and Data Methods source water population, particularly for the less abundant taxa sampled. Although the estimated larval duration remains consistent throughout the year, the changes in ocean currents results in different source water estimates for each month. Different taxa of fishes are present during different months of the year and to differing degrees within those months (some months demonstrate consistently higher abundances than others), so the total annual estimate of proportional mortality (P M ) due to entrainment would only include the data from the months when those taxa are present and are weighted by the expected abundance of the taxa during those months. These weights were calculated using data from independent studies where sampling was done over at least a period of one year. The annual estimate of P M for a given taxa is calculated as follows: 12 d P 1 f (1 PE ), (3) M i i i 1 where f i = the fraction of the source water population from the year present during month or survey period i, and d = period of exposure in days that the larvae are exposed to entrainment mortality represented by the PE i, the period of exposure in days that the larvae are exposed to entrainment mortality (d) is taxon specific and is calculated based on the difference between the youngest and oldest larvae sampled at the entrainment location. Assumptions associated with the estimation of P M include the following: Each survey period represents a new and independent cohort of larvae; The estimates of larval abundance used for weighting the monthly estimates (f i ) are representative of long-term conditions within Monterey Bay; The conditional probability of entrainment, PE i, is constant within each monthly survey period (i); The conditional probability of entrainment, PE i, is constant within each of the size classes of larvae present during each monthly period (i); Lengths and applied growth rates of larvae accurately estimate taxon specific period of larval duration subject to entrainment (d). DeepWater Desal Preliminary Intake Impact Assessment Modeling 2-4

29 2.0: Modeling and Data Methods Kirby Park Ocean North Moss Landing Harbor and Area of Detail Elkhorn Slough Monterey Bay Ocean South Dairies 1 km Harbor Mouth Harbor Bridge Moss Landing Harbor Hwy 1 Bridge Retired Units 1-5 Discharge Combined-Cycle Units Intake (formerly Units 1-5 Intake) Units 6-7 Intake Moss Landing Power Plant Units 6-7 Discharge Sandholdt Pier km Source Water Sampling Entrainment Sampling Figure 2-1. Location of stations sampled during the MLPP 316b study. DeepWater Desal Preliminary Intake Impact Assessment Modeling 2-5

30 2.0: Modeling and Data Methods 2.2 Biological Data Used in Modeling The following section describes the biological data used in the ETM modeling assessment Sampling Methods Plankton sampling for the MLPP 316(b) study was conducted at a station in front of each intake and at six additional stations (two locations in Elkhorn Slough, one near the harbor bridge, one at the harbor mouth, and two outside of the harbor complex in the offshore area) (Figure 2-1). Of these six stations three have been used in this assessment due to their proximity to the proposed intake location. The stations used are the harbor mouth (HM), and stations north (N1) and south (S1) of the harbor (Figure 2-2). The sampling at theses stations was only done monthly from September 1999 through May The sampling was done using a bongo frame with two 0.71 m (2.3 ft) diameter openings that were each equipped with 335 µm mesh plankton nets and codends, and a calibrated flowmeter. The bongo nets were lowered as close to the bottom as possible, and once at the correct depth, the boat was moved forward and the nets retrieved at an oblique angle (winch cable at about a 45 angle). The winch retrieval speed was constant at approximately 1 ft/sec. Samples were collected at these stations once per month during daylight hours with one sample being collected near low tide and one near high tide. Table 2-1 presents a description, depth, and location of these three stations. The target volume for each sample was 40 m 3. Upon successful completion of a tow, the nets were retrieved from the water and all of the collected material was rinsed into the cod-end. The contents of both nets were combined into a single, labeled jar (constituting one sample) immediately after collection and were preserved in 70 percent ethanol. Each sample was tagged with an internal and external label containing the location, date, time, and station depth. In addition, that information was logged onto a sequentially numbered data sheet. The sample s unique identifier was used to track it through laboratory processing, data analyses, and reporting. In the laboratory all larval fishes were removed from each sample and placed in labeled vials containing 70 percent ethanol. Fish eggs were not removed from the samples. Although there are descriptions of many marine eggs, the taxonomy remains difficult and time consuming, with many of the eggs not being able to be identified to the species level and being placed in lump categories which could be made up of many different species from possibly different genera. The identity and life stage of each larval fish was recorded on a data sheet for each sample. A laboratory quality control (QC) program for all levels of laboratory sorting and taxonomic identification was applied to all samples. DeepWater Desal Preliminary Intake Impact Assessment Modeling 2-6

31 2.0: Modeling and Data Methods Table 2-1. Collection specifications for source water sampling at MLPP. Station Name Description Location (Lat. / Long.) Station Depth at MLLW (m / ft) Ocean North One mile north of ML harbor mouth, at the 20- meter depth contour. 36 o 48.84' N / 121 o 48.40' W 20 m / 66 ft Ocean South One mile south of ML harbor mouth, at the 20- meter depth contour. 36 o 47.44' N / 121 o 48.52' W 20 m / 66 ft Harbor Mouth Entrance to Moss Landing Harbor from Monterey Bay; between the north and south breakwaters. 36 o 48.38' N / 121 o 47.40' W 7 m / 23 ft Taxa Selected for Analysis The taxa that are analyzed in this assessment include white croaker, rockfishes, and northern anchovy which all occurred in the nearshore sampling conducted at MLPP and were all abundant in the samples collected at the three stations in the vicinity of the proposed intake location. Although CIQ goby complex 3 larvae were the most abundant larvae collected at the three stations (Table 2-2), the primary adult habitat for CIQ gobies is inside the Moss Landing harbor and Elkhorn Slough. Any impacts to the population of CIQ gobies would only occur to larvae transported out of these areas during low tides, which have a low likelihood of being returned to their native habitat inside the harbor/slough complex. Similarly, lanternfishes, which were the second most abundant larvae collected primarily occur as adults in deeper water and their larvae were potentially only collected due to transport into shallow, nearshore areas. On the assumption that these larvae have been advected outside of their natal habitat and therefore will not survive to recruit to the adult population these two groups of taxa were not included in this preliminary assessment Larval Durations The previous analysis of data for Moss Landing (Tenera 2000a) was focused on fishes associated with the harbor/slough complex so there were no data available on the lengths of the larvae for rockfishes, northern anchovy, and white croaker. The larval durations for these three taxa were derived from data collected off Diablo Canyon Power Plant (DCPP) during when high number of larvae of these two taxa were collected and measured (Tenera 2000b). The DCPP data was collected using similar methods to that used for the sample collections at the three stations used in the MLPP analysis. 3 CIQ goby complex refers to a taxonomic grouping of gobies that are extremely difficult to differentiate into separate species when the larvae are at a very young age. The acronym CIQ refers to the three species, Clevelandia ios, Ilypnus gilberti, and Quietula y-cauda. DeepWater Desal Preliminary Intake Impact Assessment Modeling 2-7

32 2.0: Modeling and Data Methods Table 2-2. Average concentrations and number collected of fish taxa at three stations (N1, S1 and Harbor Mouth) during daytime high and low tide sampling from September 1999 through May 2000 for Moss Landing Power Plant (Tenera 2000a). Average Concentration Sample Count Taxon Common Name (# per m 3 ) CIQ goby complex gobies ,405 Myctophidae lanternfishes Genyonemus lineatus white croaker Lepidogobius lepidus bay goby Sebastes spp. rockfishes Engraulis mordax northern anchovy Leptocottus armatus Pacific staghorn sculpin Sebastolobus spp. thornyheads Pleuronectidae unid. flounders Gillichthys mirabilis longjaw mudsucker Osmeridae unid. smelts Clupea pallasii Pacific herring Ammodytes hexapterus Pacific sand lance Hypsoblennius spp. blennies Atherinidae unid. silversides Coryphopterus nicholsi blackeye goby Cottidae unid. sculpins Pleuronectiformes unid. flatfishes Citharichthys spp. sanddab larval/post-larval fish, unid. unidentified larval fishes Parophrys vetulus English sole Cottus asper prickly sculpin Sardinops sagax Pacific sardine Artedius spp. sculpins Platichthys stellatus starry flounder Bathylagus ochotensis popeye blacksmelt Cebidichthys violaceus monkeyface eel Psettichthys melanostictus sand sole Paralichthyidae unid. lefteye flounders & sanddabs Clupeiformes herrings and anchovies Brosmophycis marginata red brotula Pleuronichthys verticalis honeyhead turbot Typhlogobius californiensis blind goby Zaniolepis spp. combfishes Bathymasteridae unid. ronquils Agonidae unid. poachers Cololabis saira Pacific saury Totals ,047 DeepWater Desal Preliminary Intake Impact Assessment Modeling 2-8

33 2.0: Modeling and Data Methods 2.3 MLPP Source Water Body Calculations The following section describes the data used, and assumptions applied, in determining the source water used in this preliminary impact assessment for an intake line which is at a depth of approximately 18 m (60 ft) about 1 km (0.6 mi) to the north of the Moss Landing Harbor mouth (Figure 2-2) Data Sources and Processing Data on currents in the vicinity of the intake location were collected from two sources: nearshore sub-surface currents were obtained from an acoustic Doppler current profiler (ADCP) deployed at the Monterey Bay Aquarium Research Institute (MBARI) M0 mooring (Figure 2-2) and surface currents were obtained from a network of CODAR Ocean Sensors, Ltd. SeaSonde high-frequency (HF) radars deployed by COCMP (Figure 2-3). All of the data were provided by CeNCOOS. A combination of these velocity measurements was used to project the extent of water that could be transported to the intake location over selected planktonic larval duration periods. a) b) Figure 2-2. Locations of a) M0 current meter in relation to plankton sampling locations (N1, S1 and HM) and the intake location, and b) close up of plankton sampling locations and the two proposed DWD intakes in relation to nearshore subtidal bathymetry. A potential location for a deepwater intake is also shown. DeepWater Desal Preliminary Intake Impact Assessment Modeling 2-9

34 2.0: Modeling and Data Methods Figure 2-3. Ocean surface current vectors measured on October 1, 2010 at 0000 UTC in the Monterey Bay, California region by the CeNCOOS CODAR SeaSonde stations (black triangles). Shown are vectors of both the 6 km (3.7 mile) resolution coverage offshore (left) and the higher 2 km (1.2 mile) resolution coverage closer to the coast, shaded according to their velocity per the color-bar (right). The M0 ADCP data were collected for 140 seconds every 10 minutes from June 14, 2010 to September 30, in 4 m (13 ft) bins, with the center of the first bin located at the 6 m (20 ft) depth. These ADCP data were averaged across the hour to compliment the hourly frequency of the CODAR measurements. Means were then calculated from the 4 20 m (13 66 ft) ADCP bins to derive averages that approximated the depth of the water at the proposed intake location. The progressive current vectors from the M0 ADCP for the 6 and 18 m (20 and 59 ft) depth bins both show similar seasonal changes with predominantly upcoast flow from late spring through fall and downcoast and onshore flow during winter and early spring. As would be expected, the greater current speeds at the shallower depth result in greater onshore flow during the winter and spring months. DeepWater Desal Preliminary Intake Impact Assessment Modeling 2-10

35 2.0: Modeling and Data Methods The velocity of ocean currents measured at the water s surface typically decays with increasing depth and this relationship was seen in the velocities measured. Due to their offshore and surface origin, CODAR speeds interpolated to the location of the M0 mooring were about twice the magnitude of the averages measured there at mid-depths by the ADCP. To better model the extent of waters potentially entrained at the intake location, respective of larvae living subsurface, the CODAR-derived surface currents were scaled to approximate sub-surface magnitudes. The proximity of the M0 mooring to the CODAR measurement field allowed the surface current values measured over the aforementioned time period to be linearly interpolated to the M0 location. The U (east-west) and V (north-south) components of the CODAR and ADCP velocities were considered separately in their relationship with depth. Further, as there are seasonal variations in the currents, each calendar month was assessed independently. The difference between the CODAR and ADCP, as a percentage of the magnitude of the CODAR measurement, was calculated. Absolute values of each component measured hourly in the same calendar month by CODAR were subtracted from the absolute values of the corresponding average ADCP component for the 4 20 m (13 66 ft) depth range. The mean of these differences for the month was then divided by the mean of the absolute value of the CODAR component measured that month. This produced a percentage by which to scale the CODAR data to the magnitudes of the sub-surface currents. Application of these scaling factors to adjust the CODAR data did not affect the directional component of velocity (Figure 2-4). a) b) Figure 2-4. The a) U and b) V components of velocity measured over a representative period (approximately two days) at the surface by CODAR and at depth by the M0 ADCP CODAR Back-Projections A computer model was developed in MATLAB with forcing from the combined CODAR and M0 ADCP measurements to reverse-track (back-projections) source water flowing to the intake location ( N, W) for durations of up through 46 days (maximum estimated d). There were 30 back projections calculated for each month from October 2010 to September using randomly selected hours within ± 1 day of the first day of each month as the starting DeepWater Desal Preliminary Intake Impact Assessment Modeling 2-11

36 2.0: Modeling and Data Methods time. The 46 day time period allowed assessment for a range of larval planktonic durations exhibited by the most prevalent larval fish taxa found during sampling conducted at the three stations sampled in (see Section 2.2). The data used in the back projections were the 6 km (offshore) and 2 km (nearshore) resolution surface currents from CODAR averaged using the method described above over the 4 20 m depth range and scaled to the hourly 12 m (39 ft) averages measured at M0. The arial extent of this adjusted CODAR data extended approximately 150+ km (93 mi) offshore and alongshore from the intake location. This arbitrary extent ensured the modeled area encompassed the maximal extent a particle was expected to be back-tracked to according to an estimation of current velocity and duration. The velocity components of the currents (U, positive to east and V, positive to north) were calculated for each of the 9,217 hours from August 15, 2010 [(October 1, day) 46 days] through September 2, [(September 1, ) + 1 day] and collated into files each representing an hour of measurements. For each survey date, the scaled U and V components of the ocean current velocity measured that hour were first linearly interpolated to the location of the given intake. The sign of the U and V components were then reversed to calculate the location a particle (or presumably planktonic individual) would have originated from the hour before and been carried by the ocean currents toward the intake. This process was repeated for each prior hour from the survey date, through 46 previous days, interpolating the U and V components of velocity at each hour to the location calculated in the prior time-step and reversing sign to back-project the location the particle would have been the hour before. If the back-projection of a particle caused its track to cross a land boundary, the distance the particle was projected to travel was applied first to the direction in U. If land was still encountered the distance was then applied to the V direction. If both attempts to move the particle alongshore failed, it was held in position for that time-step and the process repeated the next hour, until the current moved the particle past or away from the land mass. The result of the combined analysis of CODAR and the M0 ADCP, for 10, 20, and 30 days duration backprojections, are shown in Figures 2-5 to 2-7 based on each survey beginning on the first day of each of the months. Although the back-projections in Figures 2-5 to 2-7 are shown for periods of 10, 20, and 30 days the coastal distance corresponding to the maximum upcoast and downcoast extent of the 30 projections for the larval duration for each taxon will be used as the source water in the impact assessment based on that taxa s calculated larval duration. These figures show that the 30 day monthly back-projections from the intake location generally stay within Monterey Bay. But, each month is unique with wide variation in the distance that could be traveled in a 30 day period. Based on these back-projections, some months had little water movement (e.g., March 1, [Figure 2-6b]) while others had water traveling over longer distance (e.g., August 1, [Figure 2-7c]). For instance, for March, the excursion over the prior 30 days all stay very close to the proposed intake location, yet for April (Figure 2-6c), many of the projections for the previous 10 days (blue in Figure 2-6) show that water at the intake came either from near the City of Monterey or just close to the intake, and during an additional 10 previous days the water had come from either central Monterey Bay or just upcoast DeepWater Desal Preliminary Intake Impact Assessment Modeling 2-12

37 2.0: Modeling and Data Methods of the intake. The water from prior days had moved from either central Monterey Bay or along the coast line from north of the intake to about Santa Cruz. DeepWater Desal Preliminary Intake Impact Assessment Modeling 2-13

38 2.0: Modeling and Data Methods a) b) c) d) Figure 2-5. CODAR back-projections scaled to ADCP data from buoy M0 and averaged over the 4-20 m (13 60 ft) depth range for dates ending on a) October 1, b) November 1, c) December 1, 2010, and d) January 1,. The back projections use 30 randomly selected start times on the hour ± 1 day. Each back-projection changes color from blue to green to red to represent the time periods of 0 10 d, d, and d, respectively, for each projection. DeepWater Desal Preliminary Intake Impact Assessment Modeling 2-14

39 2.0: Modeling and Data Methods a) b) c) d) Figure 2-6. CODAR back-projections scaled to ADCP data from buoy M0 and averaged over the 4-20 m (13-60 ft) depth range for dates ending on a) February 1, b) March 1, c) April 1, and d) May 1,. The back projections use 30 randomly selected start times on the hour ± 1 day. Each backprojection changes color from blue to green to red to represent the time periods of 0 10 d, d, and d, respectively, for each projection. DeepWater Desal Preliminary Intake Impact Assessment Modeling 2-15

40 2.0: Modeling and Data Methods a) b) c) d) Figure 2-7. CODAR back-projections scaled to ADCP data from buoy M0 and averaged over the 4-20 m (13-60 ft) depth range for dates ending on a) June 1, b) July 1, c) August 1, and d) September 1,. The back projections use 30 randomly selected start times on the hour ± 1 day. Each backprojection changes color from blue to green to red to represent the time periods of 0 10 d, d, and d, respectively, for each projection. DeepWater Desal Preliminary Intake Impact Assessment Modeling 2-16