Research date: 2 September 2026. Illustrative Port Meridian; public sources only.
Targeted public-source synthesis; not a systematic review. Reported facts, calculations, assumptions, inferences, disputed evidence and unknowns are kept separate. Operator publications are treated as disclosures rather than independent performance audits.
World Bank · March 2019 · Official report
Geographic scope: International desalination project database.
Locator: Printed pp. 22-25, 40-48, 71-85; range at PDF p. 58, Table 4.3 at pp. 59-60
Evidence note: Historical SWRO project costs span $0.49-$2.86/m³ in the report’s 2016 USD basis. Table 4.3 combines reported and modeled water costs; missing costs use 7% capital cost and 25 years. Regional conditions, capacity and financial structures affect comparability.
Limits: A historical database, including planned plants, not a 2026 bid range or uniform delivered-water tariff.
Claims: C05, I01. Public retrieval: HTTP 200. SHA-256: 3f6741bd8095b1e4dd092629664fd81839cfa3f2949e2aa340f92b6749828ea1.
U.S. Department of Energy · October 2017 · Government
Geographic scope: United States reference systems.
Locator: Executive summary pp. viii-x; Table 3-1 p. 14; system boundary discussion
Evidence note: DOE separates intake, pretreatment, membrane separation, post-treatment and concentrate management. Its current-typical RO separation entry is 3.3 kWh/m³. The report explicitly distinguishes on-site electricity from primary energy and conveyance.
Limits: 2016 U.S. reference conditions; 3.3 is the RO step, not a whole-plant guarantee. Do not add primary-energy losses to an electricity bill.
Claims: C03, A05. Public retrieval: HTTP 200. SHA-256: aae88476377136b109db7216854dd9355da9d62b1632ad45365c991675d36496.
U.S. Environmental Protection Agency · 2017 · Government
Geographic scope: United States compilation; several local project settings.
Locator: §1.5 pp. 1-5 to 1-6; ch. 8-10; §11.2 pp. 11-1 to 11-6 (PDF pp. 122-127)
Evidence note: EPA discusses site-specific conservation, treatment barriers, source control and monitoring. Its cost chapter reports a broad $0.7-$1.6/m³ reuse range from a 2014 study, with conveyance and brine disposal in high-end cases. A complex planned reuse train is projected near 3 kWh/m³, partly reflecting conservative planning assumptions.
Limits: Historical compilation with varied cost boundaries and dollar vintages. It is not a current legal standard, a universal energy limit, or a design approval.
Claims: C04, C05, C08, I01. Public retrieval: HTTP 200. SHA-256: 04a9b993a30f71ff419f7d75c767aa3e23730d329d8ecdba75c23ec427d1afe6.
Orange County Water District · Undated page; 2023 expansion disclosed · Operator
Geographic scope: Orange County, California, United States.
Locator: “How much water does the GWRS produce?” and “When did the GWRS come online and how much did it cost?”
Evidence note: GWRS reports 130 million U.S. gallons/day of capacity after its 2023 final expansion. The FAQ gives $284 million for that expansion and describes microfiltration, RO, UV/peroxide and groundwater recharge.
Limits: Expansion cost on existing infrastructure, not the price of a new complete 130-MGD system. Operator account; local recharge conditions matter.
Claims: C02, I01. Public retrieval: HTTP 200. SHA-256: 81a1b31e58bf71583c39e6b91e187439acbc6a8df2d0343c8eafd8d2a5ad77ec.
San Diego County Water Authority · 29 June 2015 · Operator
Geographic scope: Carlsbad and San Diego County, California, United States.
Locator: Project scope and Water Purchase Agreement paragraphs
Evidence note: The 2015 release describes a $1 billion project including plant, 10-mile pipeline and distribution upgrades. The purchase agreement was for 48,000-56,000 acre-feet/year. The release projected average plant output of 50 million U.S. gallons/day.
Limits: 2015 construction-era disclosure; projected output and historical capital scope, not verified current annual deliveries or a present tariff.
Claims: C06. Public retrieval: HTTP 200. SHA-256: f99bfbafd097fa794736dcdf6e9c8d5ce74796edfded4fe91ea9642e946365bf.
California State Water Resources Control Board · 8 February 2017 · Government
Geographic scope: California, United States.
Locator: Finding 6, printed/PDF p. 2
Evidence note: The Board reported a 22.5% cumulative reduction in statewide urban potable water use for June 2015-December 2016 relative to 2013.
Limits: Drought-period aggregate demand change. It does not establish permanent savings, causal attribution, or the remaining efficiency potential of this fictional city.
Claims: C01, I01. Public retrieval: HTTP 200. SHA-256: 4f5030846ffd6c68b744133344cd93842ed838aa219b490d1f0411b859b306a7.
California State Water Resources Control Board · Current public overview; retrieved 2 September 2026 · Government
Geographic scope: California, United States; jurisdiction example.
Locator: “Ocean Plan Chapter III.M” and supporting reports
Evidence note: California’s framework addresses siting, design, intake and discharge measures to reduce harm to marine life. The overview links both technical reports and the governing plan.
Limits: An example of one jurisdiction’s framework. Applicable local rules, decisions and permits must be established separately.
Claims: C09. Public retrieval: HTTP 200. SHA-256: 9a9dee2f6e8ad0c8fd80e306127a0d54369ff725436ab5a50c6bd1300798725b.
City of Santa Barbara · Undated current page; historical 2015-2018 events · Operator
Geographic scope: Santa Barbara, California, United States.
Locator: History and “Costs” paragraphs
Evidence note: The city describes extended standby followed by reactivation, $72 million reactivation capital, and estimated operating costs of $4.1 million/year at full production versus $1.5 million in standby.
Limits: Historical disclosed figures with no uniform current-dollar basis. Reactivation is not a greenfield project; financing and grants change net payer cost.
Claims: C07, I01. Public retrieval: HTTP 200. SHA-256: 8db713b2b4e629bf3d5ba86943c989234d7ad5edf64dbb48a70b38c15532e3e8.
Giammar et al.; ACS ES&T Engineering; NREL/NLR institutional record · 2022 journal issue (copyright 2021) · Primary research
Geographic scope: United States municipal reuse case studies.
Locator: Institutional abstract; DOI 10.1021/acsestengg.1c00351; 2(3), 489-507
Evidence note: WaterTAP3 case modeling reports 0.84 kWh/m³ for an RO-based reuse train versus 0.30 for a carbon-based train. The abstract identifies utilization, capital cost and lifetime as important cost sensitivities.
Limits: Institutional abstract inspected; full-paper methods were not used to validate project costs. Case models are not guaranteed whole-city energy performance.
Claims: C04, A05. Public retrieval: HTTP 200. SHA-256: fd09c23eb64bcc29b4cc59e5e13ad92178d6ea4e31f760600ed64f841b474eb4.
International Energy Agency · 2016 analysis; released 20 March 2017 · Official report
Geographic scope: Global water and energy systems.
Locator: Energy for water, pp. 27-32; Figure 8 and Box 2 (PDF pp. 29-34)
Evidence note: The IEA separates abstraction, treatment, desalination, transport, distribution and wastewater processes. This supports a comparison boundary that includes both treatment and delivery energy.
Limits: Global ranges and modeled outlooks are not a site’s electricity bill. This dossier does not repeat its 2040 projections as observed facts.
Claims: C03, A05. Public retrieval: HTTP 200. SHA-256: da61c91c43412a97d03986c1148080fdfc03874807f0dac36f4f859900d2ddad.
U.S. Environmental Protection Agency · January 2025 file · Government
Geographic scope: United States electricity emissions accounting.
Locator: Step 3, PDF p. 3; scope and grid-loss explanation
Evidence note: EPA estimates electricity-use emissions by multiplying electricity consumption by an appropriate output emission rate. It distinguishes generation emissions from transmission and distribution losses.
Limits: The reader’s intensity is an assumed kg CO₂e/kWh scenario, not an extracted regional factor. It excludes embodied materials, chemicals, direct process emissions and a marginal-grid analysis.
Claims: C11. Public retrieval: HTTP 200. SHA-256: bc51d3c859d19d0a2b0a5a7ace5c77df96c7a1be3ef9d6d22733e1236403e202.
Subsurface Intake Expert Panel / California State Water Board · June 2024 report; 12 May 2025 response memo · Disputed evidence
Geographic scope: California, United States; intake-feasibility guidance.
Locator: Memo PDF pp. 1-4; panel report §4 and §6.2
Evidence note: The panel proposes an intake-feasibility framework. The regulator’s attached memo says it is a high-level guide, questions technical support for some generalizations, and warns that proposed procedural changes should not be confused with existing requirements.
Limits: Read the report together with the response. Neither justifies declaring an unstudied site feasible or infeasible.
Claims: C10. Public retrieval: HTTP 200. SHA-256: d1fe9c9cb488d82a6aa01cdb453440a035449a07dfbcdb1f5367815ab97fc849.
Science Advisory Panel for California Water Boards · March 2012 · Official report
Geographic scope: California coastal applications and wider scientific literature.
Locator: Executive summary; §6 pp. 23-28; §10.5 data gaps (PDF pp. 32-37, 54)
Evidence note: Dense brine can expose seabed organisms to elevated salinity. The panel discusses site-specific mixing, co-discharge and field monitoring, and identifies gaps in chronic/sublethal-effects evidence.
Limits: Historical scientific advice, not a current permit. Mixing performance and ecological effects require local evidence; a simple mass balance cannot predict a safe outfall.
Claims: C09, I02. Public retrieval: HTTP 200. SHA-256: 03b9b81cb29b6608649188cabf51096c5affe06c1117f9e8babfd0db87688e1c.
“Observed” means reported by the cited source, not independently measured by this demo. Assumptions and calculated results are not sourced observations.
California reported 22.5% lower cumulative urban potable use in June 2015-December 2016 than in 2013.
Evidence: S06.
Scope: Drought-period statewide result; no causal or permanent-savings claim.
OCWD reports 130 MGD capacity and a $284 million final expansion completed in 2023.
Evidence: S04.
Scope: Expansion capital only; capacity is not annual production.
DOE separates desalination unit operations; IEA includes transport and distribution as distinct loads.
Scope: Do not use the RO membrane step as total delivered-water energy.
Giammar et al. model 0.84 kWh/m³ for one RO-based reuse train. EPA describes a complex planned treatment train projected near 3.0 kWh/m³.
Scope: Examples from different case studies, not a statistically representative range.
World Bank reports SWRO costs spanning $0.49-$2.86/m³ in 2016 USD; EPA’s 2017 compilation gives a $0.7-$1.6/m³ reuse range from earlier research.
Scope: Different vintages, scopes and financing. These are not a current price ranking.
The 2015 Carlsbad disclosure puts the plant, pipeline and distribution work in a $1 billion project.
Evidence: S05.
Scope: Historical nominal project disclosure; not a 2026 unit tariff.
Santa Barbara discloses $4.1 million/year full-production operating cost and $1.5 million in standby, alongside reactivation capital.
Evidence: S08.
Scope: Historical estimates on an undated page; not a quote for Port Meridian.
EPA discusses source control, multiple treatment barriers, monitoring and operations for potable reuse.
Evidence: S03.
Scope: This dossier makes no finding about a local approval pathway or finished-water safety.
Intake impacts, brine mixing and organism exposure need local evaluation.
Scope: No generic recovery ratio or diffuser proves ecological acceptability.
The 2025 regulator memo challenges aspects of the 2024 intake panel report and distinguishes proposed procedures from existing requirements.
Evidence: S12.
Scope: Both positions are available in one linked PDF.
Electricity consumption multiplied by an appropriate emission rate gives electricity-use emissions.
Evidence: S11.
Scope: Select CO₂ or CO₂e consistently; a location-based inventory differs from marginal effects.
Port Meridian is a fictional coastal city of 300,000 residents. The utility serves port, tourism and industry; assumed current demand is 200,000 m³/day and dry-year existing supply is 100,000 m³/day.
Scope: A severe regional shortage; not a typical residential-use benchmark.
Replace a 100,000 m³/day annual-average service gap. New water is measured at the utility delivery interface; common downstream distribution is excluded.
Scope: If 100,000 is instead a peak-day requirement, this screen must be rebuilt.
Assume 20,000 m³/day verified demand reduction and 75,000 m³/day eligible effluent AFTER conservation and existing commitments; assume 80% net reuse recovery.
Scope: Eligible feed is measured after commitments and conservation; treatment and delivery losses are represented by the 80% net recovery. No gross sewer volume is counted twice.
Assume 2026 USD reference capital at 100,000 m³/day nameplate: $350 million SWRO and $200 million reuse; scale linearly with capacity. Assume 4% real finance, 30 years, annual fixed O&M 2% of capital and non-energy variable O&M $0.15/m³.
Scope: No project estimate. No land, major trunk upgrades, unusual outfalls, new secondary sewage plant, taxes, grants, financing during construction or contingency reserve beyond the assumed capital allowance.
SWRO uses 3.5 + 0.3 = 3.8 kWh/m³. Reuse uses 0.84 + 0.16 = 1.0 kWh/m³. Default power is $0.12/kWh and emissions intensity 0.35 kg CO₂e/kWh.
Scope: Evidence-informed assumptions, not measured performance. Reuse begins at available secondary effluent; downstream barriers may add energy.
Assume 35 g/L feed salinity and 45% recovery; neglect product salt, density differences, pretreatment losses and dilution water.
Scope: This is a mass-balance illustration, not a discharge or intake design.
100,000 m³/day is 36.5 million m³/year and about 26.42 million U.S. gallons/day.
Calculation: 100000 × 365; 100000 / 3785.411784.
Scope: 365-day year; U.S. liquid gallons.
At 90% utilization the arithmetic capacity is 111,111 m³/day. A 100,000 m³/day plant at 90% yields only 32.85 million m³/year.
Calculation: 100000 / 0.90; 100000 × 365 × 0.90.
Scope: Annual balance only; storage, redundancy and outage duration remain unmodeled.
20,000 m³/day savings + 60,000 reuse + 20,000 residual supply = 100,000.
Calculation: 75000 × 0.80 = 60000; 100000 - 20000 - 60000 = 20000.
Scope: Conditional on A03. The residual is a candidate for desalination or another firm source.
At 3.8 kWh/m³, full-target SWRO needs 138.7 GWh/year, averages 15.83 MW and costs $16.644 million/year for electricity at $0.12/kWh.
Calculation: 36500000 × 3.8 / 1e6; 138700000 / 8760 / 1000; 138700000 × 0.12.
Scope: Electricity only; excludes grid losses and embodied emissions.
At the defaults the SWRO screen is $1.44/m³ ($52.39 million/year) and a hypothetical full-target reuse screen is $0.74/m³ ($27.15 million/year).
Calculation: CRF = r(1+r)^n / ((1+r)^n - 1); cost = K(CRF+f)/(365q) + v + ep.
Scope: Reuse cannot deliver the full target under A03. Equal-volume economics are illustrative; do not interpret the cheaper column as available supply.
SWRO electricity emissions are 48,545 t CO₂e/year at 0.35 kg/kWh; they range from 6,935 to 97,090 t/year when the assumed factor moves from 0.05 to 0.70.
Calculation: 138700000 × g / 1000.
Scope: Electricity-use emissions only; neither lifecycle footprint nor a marginal-grid forecast.
At 100,000 m³/day average product and 45% recovery, intake is about 222,222 m³/day and concentrate 122,222 m³/day, at roughly 63.6 g/L before dilution.
Calculation: q/R; q/R - q; 35/(1-R).
Scope: A06 approximation. At 90% utilization on-stream flows are each divided by 0.90.
With 20,000 m³/day savings, 100,000 m³/day eligible effluent at 80% recovery would cover the remaining gap.
Calculation: (100000 - 20000) / .80 = 100000.
Scope: Same dry-year reliability, recovery, delivery and cost conditions must hold.
At the chosen intensities, 60,000 reuse plus 20,000 SWRO uses 49.64 GWh/year, 64.2% below full-target SWRO.
Calculation: (60000 × 1 + 20000 × 3.8) × 365 / 1e6.
Scope: No additional energy savings credit for conservation. Fixed energy and small-plant inefficiency are not modeled.
An assumed $3.65 million/year program saving 20,000 m³/day costs $0.50/m³ saved; at half the yield, $1.00/m³.
Calculation: 3650000 / (saving × 365).
Scope: Gross program spending per saved unit; not a ratepayer bill or a net benefit estimate.
An illustrative ceiling of 0.5 kg CO₂e/m³ requires a grid intensity of about 0.132 kg CO₂e/kWh or lower for the 3.8-kWh/m³ option.
Calculation: 0.5 / 3.8.
Scope: An analytical threshold, not a regulatory limit or user policy.
Lifting one m³ through 100 m at 80% efficiency takes about 0.341 kWh, before pipeline friction.
Calculation: 1000 kg/m³ × 9.81 m/s² × 100 m / (0.80 × 3600000 J/kWh).
Scope: Simplified hydraulic work; the actual alignment and pumps are unknown.
The evidence supports testing conservation and reuse first while preserving a seawater option for the remaining dependable gap.
Evidence: S01, S03, S04, S06, S08.
Scope: Conditional synthesis. The 20/60/20 split is illustrative, not optimized or approved.
Diverting treated effluent into reuse can reduce water available to dilute a colocated desalination discharge.
Evidence: S13.
Scope: Mass-balance inference from the panel’s co-discharge discussion; the fictional city has no designed outfall.
No local measurements establish permanent savings, eligible wastewater, seasonal load, product quality requirements, hydrogeology, marine mixing, grid connection, land, delivery alignment, costs or approvals.
Scope: These missing inputs prevent an engineering, legal or procurement recommendation.
Test 20,000 m³/day of sustained savings and 60,000 m³/day of reuse, then investigate a 20,000 m³/day residual supply. Preserve the option to expand desalination if the first two resources do not materialize.
Evidence claims: C01, C02, C04, C08. Assumptions: A01, A02, A03. Calculations: F03, F08, F09.
Supporting source union: S03, S04, S06, S09.
Additional background: S01.
Counterargument: A city with little remaining waste or scarce, highly committed effluent may gain very little from this sequence. An urgent shortage may require parallel project development rather than waiting for one option to finish.
What would change the conclusion: If eligible post-conservation effluent reaches 100,000 m³/day at 80% recovery, reuse plus savings could eliminate the residual. If only 37,500 m³/day is eligible, reuse yields 30,000 and the residual rises to 50,000.
High confidence in the need to test; low confidence in the illustrative split.
If seawater must supply the entire annual-average gap, 90% utilization implies about 111,000 m³/day of nameplate capacity. Storage, parallel trains and independent power still determine whether the city gets water during an outage.
Evidence claims: C03, C06, C07. Assumptions: A02, A05. Calculations: F01, F02, F04.
Supporting source union: S02, S05, S08, S09, S10.
Additional background: S03.
Counterargument: A larger nameplate does not protect against a shared intake failure, power outage or red tide. A plant used mainly in drought may have high insurance value even when its delivered-water cost is high.
What would change the conclusion: A peak-day rather than annual-average requirement changes the sizing problem. A three-day complete outage at this full target requires 300,000 m³ of stored or alternate water before any safety margin.
High confidence in the arithmetic; dependable yield remains unproven.
Full-target SWRO uses 138.7 GWh/year in this screen. A $0.10/kWh change moves its water cost by $0.38/m³. Cleaner power lowers electricity emissions, while capital and marine impacts remain.
Evidence claims: C03, C04, C11. Assumptions: A04, A05. Calculations: F04, F05, F06, F11.
Supporting source union: S02, S03, S09, S10, S11.
Counterargument: A low annual emissions factor does not prove low marginal emissions at the hours the plant operates. Renewable certificates alone do not establish physical hourly supply or eliminate lifecycle impacts.
What would change the conclusion: For an illustrative 0.5 kg CO₂e/m³ electricity-emissions ceiling, the factor must be about 0.132 kg CO₂e/kWh or lower. Expensive delivery or a complex reuse train can also narrow the energy advantage.
High confidence in sensitivity; grid, alignment and treatment choices are unknown.
Commission the intake, outfall and ecological evidence before treating seawater as an available supply. Read the intake panel’s recommendations with the regulator’s critique attached to them.
Evidence claims: C09, C10. Assumptions: A06. Calculations: F07.
Supporting source union: S07, S12, S13.
Counterargument: Subsurface intakes can reduce impacts, but geological yield, scale, land and construction conditions matter. Conversely, expense alone does not prove that an option is infeasible.
What would change the conclusion: A demonstrated intake yield, acceptable site-specific discharge performance, and an applicable approval pathway could make desalination viable. A protected habitat, poor mixing, or inadequate intake yield could rule out this site.
High confidence that the gate matters; no site feasibility finding.
# THE EVIDENCE ROOM — source and claim ledger Research date: 2 September 2026. Illustrative Port Meridian; public sources only. Targeted public-source synthesis; not a systematic review. Reported facts, calculations, assumptions, inferences, disputed evidence and unknowns are kept separate. Operator publications are treated as disclosures rather than independent performance audits. ## Source register ### S01 · The Role of Desalination in an Increasingly Water-Scarce World World Bank · March 2019 · Official report Geographic scope: International desalination project database. [Open source at evidence](https://documents1.worldbank.org/curated/en/476041552622967264/pdf/135312-WP-PUBLIC-14-3-2019-12-3-35-W.pdf#page=58) Locator: Printed pp. 22-25, 40-48, 71-85; range at PDF p. 58, Table 4.3 at pp. 59-60 Evidence note: Historical SWRO project costs span $0.49-$2.86/m³ in the report’s 2016 USD basis. Table 4.3 combines reported and modeled water costs; missing costs use 7% capital cost and 25 years. Regional conditions, capacity and financial structures affect comparability. Limits: A historical database, including planned plants, not a 2026 bid range or uniform delivered-water tariff. Claims: C05, I01. Public retrieval: HTTP 200. SHA-256: `3f6741bd8095b1e4dd092629664fd81839cfa3f2949e2aa340f92b6749828ea1`. ### S02 · Bandwidth Study on Energy Use and Potential Energy Savings Opportunities in U.S. Seawater Desalination Systems U.S. Department of Energy · October 2017 · Government Geographic scope: United States reference systems. [Open source at evidence](https://www.energy.gov/sites/default/files/2017/12/f46/Seawater_desalination_bandwidth_study_2017.pdf#page=33) Locator: Executive summary pp. viii-x; Table 3-1 p. 14; system boundary discussion Evidence note: DOE separates intake, pretreatment, membrane separation, post-treatment and concentrate management. Its current-typical RO separation entry is 3.3 kWh/m³. The report explicitly distinguishes on-site electricity from primary energy and conveyance. Limits: 2016 U.S. reference conditions; 3.3 is the RO step, not a whole-plant guarantee. Do not add primary-energy losses to an electricity bill. Claims: C03, A05. Public retrieval: HTTP 200. SHA-256: `aae88476377136b109db7216854dd9355da9d62b1632ad45365c991675d36496`. ### S03 · 2017 Potable Reuse Compendium U.S. Environmental Protection Agency · 2017 · Government Geographic scope: United States compilation; several local project settings. [Open source at evidence](https://www.epa.gov/sites/default/files/2018-01/documents/potablereusecompendium_3.pdf#page=124) Locator: §1.5 pp. 1-5 to 1-6; ch. 8-10; §11.2 pp. 11-1 to 11-6 (PDF pp. 122-127) Evidence note: EPA discusses site-specific conservation, treatment barriers, source control and monitoring. Its cost chapter reports a broad $0.7-$1.6/m³ reuse range from a 2014 study, with conveyance and brine disposal in high-end cases. A complex planned reuse train is projected near 3 kWh/m³, partly reflecting conservative planning assumptions. Limits: Historical compilation with varied cost boundaries and dollar vintages. It is not a current legal standard, a universal energy limit, or a design approval. Claims: C04, C05, C08, I01. Public retrieval: HTTP 200. SHA-256: `04a9b993a30f71ff419f7d75c767aa3e23730d329d8ecdba75c23ec427d1afe6`. ### S04 · Groundwater Replenishment System: frequently asked questions Orange County Water District · Undated page; 2023 expansion disclosed · Operator Geographic scope: Orange County, California, United States. [Open source at evidence](https://www.ocwd.com/gwrs/frequently-asked-questions/) Locator: “How much water does the GWRS produce?” and “When did the GWRS come online and how much did it cost?” Evidence note: GWRS reports 130 million U.S. gallons/day of capacity after its 2023 final expansion. The FAQ gives $284 million for that expansion and describes microfiltration, RO, UV/peroxide and groundwater recharge. Limits: Expansion cost on existing infrastructure, not the price of a new complete 130-MGD system. Operator account; local recharge conditions matter. Claims: C02, I01. Public retrieval: HTTP 200. SHA-256: `81a1b31e58bf71583c39e6b91e187439acbc6a8df2d0343c8eafd8d2a5ad77ec`. ### S05 · Carlsbad Desalination Project Crews Complete Construction of 10-Mile Pipeline San Diego County Water Authority · 29 June 2015 · Operator Geographic scope: Carlsbad and San Diego County, California, United States. [Open source at evidence](https://www.sdcwa.org/carlsbad-desalination-project-crews-complete-construction-of-10-mile-pipeline/) Locator: Project scope and Water Purchase Agreement paragraphs Evidence note: The 2015 release describes a $1 billion project including plant, 10-mile pipeline and distribution upgrades. The purchase agreement was for 48,000-56,000 acre-feet/year. The release projected average plant output of 50 million U.S. gallons/day. Limits: 2015 construction-era disclosure; projected output and historical capital scope, not verified current annual deliveries or a present tariff. Claims: C06. Public retrieval: HTTP 200. SHA-256: `f99bfbafd097fa794736dcdf6e9c8d5ce74796edfded4fe91ea9642e946365bf`. ### S06 · Resolution No. 2017-0004: Statewide Urban Water Conservation California State Water Resources Control Board · 8 February 2017 · Government Geographic scope: California, United States. [Open source at evidence](https://www.waterboards.ca.gov/board_decisions/adopted_orders/resolutions/2017/rs2017_0004.pdf#page=2) Locator: Finding 6, printed/PDF p. 2 Evidence note: The Board reported a 22.5% cumulative reduction in statewide urban potable water use for June 2015-December 2016 relative to 2013. Limits: Drought-period aggregate demand change. It does not establish permanent savings, causal attribution, or the remaining efficiency potential of this fictional city. Claims: C01, I01. Public retrieval: HTTP 200. SHA-256: `4f5030846ffd6c68b744133344cd93842ed838aa219b490d1f0411b859b306a7`. ### S07 · Ocean Plan Requirements for Seawater Desalination Facilities California State Water Resources Control Board · Current public overview; retrieved 2 September 2026 · Government Geographic scope: California, United States; jurisdiction example. [Open source at evidence](https://waterboards.ca.gov/water_issues/programs/ocean/desalination/) Locator: “Ocean Plan Chapter III.M” and supporting reports Evidence note: California’s framework addresses siting, design, intake and discharge measures to reduce harm to marine life. The overview links both technical reports and the governing plan. Limits: An example of one jurisdiction’s framework. Applicable local rules, decisions and permits must be established separately. Claims: C09. Public retrieval: HTTP 200. SHA-256: `9a9dee2f6e8ad0c8fd80e306127a0d54369ff725436ab5a50c6bd1300798725b`. ### S08 · Charles E. Meyer Desalination Plant City of Santa Barbara · Undated current page; historical 2015-2018 events · Operator Geographic scope: Santa Barbara, California, United States. [Open source at evidence](https://santabarbaraca.gov/government/departments/public-works/water-resources/water-system/water-sources/desalination) Locator: History and “Costs” paragraphs Evidence note: The city describes extended standby followed by reactivation, $72 million reactivation capital, and estimated operating costs of $4.1 million/year at full production versus $1.5 million in standby. Limits: Historical disclosed figures with no uniform current-dollar basis. Reactivation is not a greenfield project; financing and grants change net payer cost. Claims: C07, I01. Public retrieval: HTTP 200. SHA-256: `8db713b2b4e629bf3d5ba86943c989234d7ad5edf64dbb48a70b38c15532e3e8`. ### S09 · Cost and Energy Metrics for Municipal Water Reuse Giammar et al.; ACS ES&T Engineering; NREL/NLR institutional record · 2022 journal issue (copyright 2021) · Primary research Geographic scope: United States municipal reuse case studies. [Open source at evidence](https://research-hub.nlr.gov/en/publications/cost-and-energy-metrics-for-municipal-water-reuse-2/) Locator: Institutional abstract; DOI 10.1021/acsestengg.1c00351; 2(3), 489-507 Evidence note: WaterTAP3 case modeling reports 0.84 kWh/m³ for an RO-based reuse train versus 0.30 for a carbon-based train. The abstract identifies utilization, capital cost and lifetime as important cost sensitivities. Limits: Institutional abstract inspected; full-paper methods were not used to validate project costs. Case models are not guaranteed whole-city energy performance. Claims: C04, A05. Public retrieval: HTTP 200. SHA-256: `fd09c23eb64bcc29b4cc59e5e13ad92178d6ea4e31f760600ed64f841b474eb4`. ### S10 · Water-Energy Nexus: World Energy Outlook 2016 excerpt International Energy Agency · 2016 analysis; released 20 March 2017 · Official report Geographic scope: Global water and energy systems. [Open source at evidence](https://iea.blob.core.windows.net/assets/e4a7e1a5-b6ed-4f36-911f-b0111e49aab9/WorldEnergyOutlook2016ExcerptWaterEnergyNexus.pdf#page=30) Locator: Energy for water, pp. 27-32; Figure 8 and Box 2 (PDF pp. 29-34) Evidence note: The IEA separates abstraction, treatment, desalination, transport, distribution and wastewater processes. This supports a comparison boundary that includes both treatment and delivery energy. Limits: Global ranges and modeled outlooks are not a site’s electricity bill. This dossier does not repeat its 2040 projections as observed facts. Claims: C03, A05. Public retrieval: HTTP 200. SHA-256: `da61c91c43412a97d03986c1148080fdfc03874807f0dac36f4f859900d2ddad`. ### S11 · Using eGRID to Determine Emissions U.S. Environmental Protection Agency · January 2025 file · Government Geographic scope: United States electricity emissions accounting. [Open source at evidence](https://www.epa.gov/system/files/documents/2025-01/using-egrid-to-determine-emissions.pdf#page=3) Locator: Step 3, PDF p. 3; scope and grid-loss explanation Evidence note: EPA estimates electricity-use emissions by multiplying electricity consumption by an appropriate output emission rate. It distinguishes generation emissions from transmission and distribution losses. Limits: The reader’s intensity is an assumed kg CO₂e/kWh scenario, not an extracted regional factor. It excludes embodied materials, chemicals, direct process emissions and a marginal-grid analysis. Claims: C11. Public retrieval: HTTP 200. SHA-256: `bc51d3c859d19d0a2b0a5a7ace5c77df96c7a1be3ef9d6d22733e1236403e202`. ### S12 · Final Desalination Subsurface Intake Panel Report, with regulator response memo Subsurface Intake Expert Panel / California State Water Board · June 2024 report; 12 May 2025 response memo · Disputed evidence Geographic scope: California, United States; intake-feasibility guidance. [Open source at evidence](https://waterboards.ca.gov/water_issues/programs/ocean/desalination/docs/2025/final-ssi-panel-report-with-memo.pdf#page=1) Locator: Memo PDF pp. 1-4; panel report §4 and §6.2 Evidence note: The panel proposes an intake-feasibility framework. The regulator’s attached memo says it is a high-level guide, questions technical support for some generalizations, and warns that proposed procedural changes should not be confused with existing requirements. Limits: Read the report together with the response. Neither justifies declaring an unstudied site feasible or infeasible. Claims: C10. Public retrieval: HTTP 200. SHA-256: `d1fe9c9cb488d82a6aa01cdb453440a035449a07dfbcdb1f5367815ab97fc849`. ### S13 · Management of Brine Discharges to Coastal Waters: Recommendations of a Science Advisory Panel Science Advisory Panel for California Water Boards · March 2012 · Official report Geographic scope: California coastal applications and wider scientific literature. [Open source at evidence](https://waterboards.ca.gov/water_issues/programs/ocean/desalination/docs/dpr.pdf#page=34) Locator: Executive summary; §6 pp. 23-28; §10.5 data gaps (PDF pp. 32-37, 54) Evidence note: Dense brine can expose seabed organisms to elevated salinity. The panel discusses site-specific mixing, co-discharge and field monitoring, and identifies gaps in chronic/sublethal-effects evidence. Limits: Historical scientific advice, not a current permit. Mixing performance and ecological effects require local evidence; a simple mass balance cannot predict a safe outfall. Claims: C09, I02. Public retrieval: HTTP 200. SHA-256: `03b9b81cb29b6608649188cabf51096c5affe06c1117f9e8babfd0db87688e1c`. ## Claim ledger “Observed” means reported by the cited source, not independently measured by this demo. Assumptions and calculated results are not sourced observations. ### C01 · Observed · Savings can be material California reported 22.5% lower cumulative urban potable use in June 2015-December 2016 than in 2013. Evidence: [S06](https://www.waterboards.ca.gov/board_decisions/adopted_orders/resolutions/2017/rs2017_0004.pdf#page=2). Scope: Drought-period statewide result; no causal or permanent-savings claim. ### C02 · Observed · Reuse operates at municipal scale OCWD reports 130 MGD capacity and a $284 million final expansion completed in 2023. Evidence: [S04](https://www.ocwd.com/gwrs/frequently-asked-questions/). Scope: Expansion capital only; capacity is not annual production. ### C03 · Observed · Treatment and delivery are separate DOE separates desalination unit operations; IEA includes transport and distribution as distinct loads. Evidence: [S02](https://www.energy.gov/sites/default/files/2017/12/f46/Seawater_desalination_bandwidth_study_2017.pdf#page=33), [S10](https://iea.blob.core.windows.net/assets/e4a7e1a5-b6ed-4f36-911f-b0111e49aab9/WorldEnergyOutlook2016ExcerptWaterEnergyNexus.pdf#page=30). Scope: Do not use the RO membrane step as total delivered-water energy. ### C04 · Observed · Reuse energy depends on the train Giammar et al. model 0.84 kWh/m³ for one RO-based reuse train. EPA describes a complex planned treatment train projected near 3.0 kWh/m³. Evidence: [S09](https://research-hub.nlr.gov/en/publications/cost-and-energy-metrics-for-municipal-water-reuse-2/), [S03](https://www.epa.gov/sites/default/files/2018-01/documents/potablereusecompendium_3.pdf#page=124). Scope: Examples from different case studies, not a statistically representative range. ### C05 · Observed · Historical prices carry different scopes World Bank reports SWRO costs spanning $0.49-$2.86/m³ in 2016 USD; EPA’s 2017 compilation gives a $0.7-$1.6/m³ reuse range from earlier research. Evidence: [S01](https://documents1.worldbank.org/curated/en/476041552622967264/pdf/135312-WP-PUBLIC-14-3-2019-12-3-35-W.pdf#page=58), [S03](https://www.epa.gov/sites/default/files/2018-01/documents/potablereusecompendium_3.pdf#page=124). Scope: Different vintages, scopes and financing. These are not a current price ranking. ### C06 · Observed · Conveyance can be a major part of a project The 2015 Carlsbad disclosure puts the plant, pipeline and distribution work in a $1 billion project. Evidence: [S05](https://www.sdcwa.org/carlsbad-desalination-project-crews-complete-construction-of-10-mile-pipeline/). Scope: Historical nominal project disclosure; not a 2026 unit tariff. ### C07 · Observed · Standby still costs money Santa Barbara discloses $4.1 million/year full-production operating cost and $1.5 million in standby, alongside reactivation capital. Evidence: [S08](https://santabarbaraca.gov/government/departments/public-works/water-resources/water-system/water-sources/desalination). Scope: Historical estimates on an undated page; not a quote for Port Meridian. ### C08 · Observed · Reuse requires a treatment and monitoring system EPA discusses source control, multiple treatment barriers, monitoring and operations for potable reuse. Evidence: [S03](https://www.epa.gov/sites/default/files/2018-01/documents/potablereusecompendium_3.pdf#page=124). Scope: This dossier makes no finding about a local approval pathway or finished-water safety. ### C09 · Observed · Marine effects depend on the site Intake impacts, brine mixing and organism exposure need local evaluation. Evidence: [S07](https://waterboards.ca.gov/water_issues/programs/ocean/desalination/), [S13](https://waterboards.ca.gov/water_issues/programs/ocean/desalination/docs/dpr.pdf#page=34). Scope: No generic recovery ratio or diffuser proves ecological acceptability. ### C10 · Disputed · An expert report is not settled guidance The 2025 regulator memo challenges aspects of the 2024 intake panel report and distinguishes proposed procedures from existing requirements. Evidence: [S12](https://waterboards.ca.gov/water_issues/programs/ocean/desalination/docs/2025/final-ssi-panel-report-with-memo.pdf#page=1). Scope: Both positions are available in one linked PDF. ### C11 · Observed · Electricity emissions are a product, with a boundary Electricity consumption multiplied by an appropriate emission rate gives electricity-use emissions. Evidence: [S11](https://www.epa.gov/system/files/documents/2025-01/using-egrid-to-determine-emissions.pdf#page=3). Scope: Select CO₂ or CO₂e consistently; a location-based inventory differs from marginal effects. ### A01 · Assumed · An illustrative city, not a procurement Port Meridian is a fictional coastal city of 300,000 residents. The utility serves port, tourism and industry; assumed current demand is 200,000 m³/day and dry-year existing supply is 100,000 m³/day. Scope: A severe regional shortage; not a typical residential-use benchmark. ### A02 · Assumed · The service target is held fixed Replace a 100,000 m³/day annual-average service gap. New water is measured at the utility delivery interface; common downstream distribution is excluded. Scope: If 100,000 is instead a peak-day requirement, this screen must be rebuilt. ### A03 · Assumed · Only post-conservation effluent is eligible Assume 20,000 m³/day verified demand reduction and 75,000 m³/day eligible effluent AFTER conservation and existing commitments; assume 80% net reuse recovery. Scope: Eligible feed is measured after commitments and conservation; treatment and delivery losses are represented by the 80% net recovery. No gross sewer volume is counted twice. ### A04 · Assumed · A transparent financial screen Assume 2026 USD reference capital at 100,000 m³/day nameplate: $350 million SWRO and $200 million reuse; scale linearly with capacity. Assume 4% real finance, 30 years, annual fixed O&M 2% of capital and non-energy variable O&M $0.15/m³. Scope: No project estimate. No land, major trunk upgrades, unusual outfalls, new secondary sewage plant, taxes, grants, financing during construction or contingency reserve beyond the assumed capital allowance. ### A05 · Assumed · Energy defaults include an explicit delivery allowance SWRO uses 3.5 + 0.3 = 3.8 kWh/m³. Reuse uses 0.84 + 0.16 = 1.0 kWh/m³. Default power is $0.12/kWh and emissions intensity 0.35 kg CO₂e/kWh. Evidence: [S02](https://www.energy.gov/sites/default/files/2017/12/f46/Seawater_desalination_bandwidth_study_2017.pdf#page=33), [S09](https://research-hub.nlr.gov/en/publications/cost-and-energy-metrics-for-municipal-water-reuse-2/), [S10](https://iea.blob.core.windows.net/assets/e4a7e1a5-b6ed-4f36-911f-b0111e49aab9/WorldEnergyOutlook2016ExcerptWaterEnergyNexus.pdf#page=30). Scope: Evidence-informed assumptions, not measured performance. Reuse begins at available secondary effluent; downstream barriers may add energy. ### A06 · Assumed · Simple seawater balance Assume 35 g/L feed salinity and 45% recovery; neglect product salt, density differences, pretreatment losses and dilution water. Scope: This is a mass-balance illustration, not a discharge or intake design. ### F01 · Calculated · The annual water requirement 100,000 m³/day is 36.5 million m³/year and about 26.42 million U.S. gallons/day. Calculation: `100000 × 365; 100000 / 3785.411784`. Scope: 365-day year; U.S. liquid gallons. ### F02 · Calculated · Nameplate must exceed average need At 90% utilization the arithmetic capacity is 111,111 m³/day. A 100,000 m³/day plant at 90% yields only 32.85 million m³/year. Calculation: `100000 / 0.90; 100000 × 365 × 0.90`. Scope: Annual balance only; storage, redundancy and outage duration remain unmodeled. ### F03 · Calculated · A staged candidate closes the arithmetic gap 20,000 m³/day savings + 60,000 reuse + 20,000 residual supply = 100,000. Calculation: `75000 × 0.80 = 60000; 100000 - 20000 - 60000 = 20000`. Scope: Conditional on A03. The residual is a candidate for desalination or another firm source. ### F04 · Calculated · The seawater option adds a large electric load At 3.8 kWh/m³, full-target SWRO needs 138.7 GWh/year, averages 15.83 MW and costs $16.644 million/year for electricity at $0.12/kWh. Calculation: `36500000 × 3.8 / 1e6; 138700000 / 8760 / 1000; 138700000 × 0.12`. Scope: Electricity only; excludes grid losses and embodied emissions. ### F05 · Calculated · The screening cost is conditional At the defaults the SWRO screen is $1.44/m³ ($52.39 million/year) and a hypothetical full-target reuse screen is $0.74/m³ ($27.15 million/year). Calculation: `CRF = r(1+r)^n / ((1+r)^n - 1); cost = K(CRF+f)/(365q) + v + ep`. Scope: Reuse cannot deliver the full target under A03. Equal-volume economics are illustrative; do not interpret the cheaper column as available supply. ### F06 · Calculated · Carbon depends strongly on power SWRO electricity emissions are 48,545 t CO₂e/year at 0.35 kg/kWh; they range from 6,935 to 97,090 t/year when the assumed factor moves from 0.05 to 0.70. Calculation: `138700000 × g / 1000`. Scope: Electricity-use emissions only; neither lifecycle footprint nor a marginal-grid forecast. ### F07 · Calculated · Brine is a flow as well as a concentration At 100,000 m³/day average product and 45% recovery, intake is about 222,222 m³/day and concentrate 122,222 m³/day, at roughly 63.6 g/L before dilution. Calculation: `q/R; q/R - q; 35/(1-R)`. Scope: A06 approximation. At 90% utilization on-stream flows are each divided by 0.90. ### F08 · Calculated · More usable wastewater can remove the residual With 20,000 m³/day savings, 100,000 m³/day eligible effluent at 80% recovery would cover the remaining gap. Calculation: `(100000 - 20000) / .80 = 100000`. Scope: Same dry-year reliability, recovery, delivery and cost conditions must hold. ### F09 · Calculated · The candidate portfolio lowers incremental energy At the chosen intensities, 60,000 reuse plus 20,000 SWRO uses 49.64 GWh/year, 64.2% below full-target SWRO. Calculation: `(60000 × 1 + 20000 × 3.8) × 365 / 1e6`. Scope: No additional energy savings credit for conservation. Fixed energy and small-plant inefficiency are not modeled. ### F10 · Calculated · Conservation economics depend on sustained yield An assumed $3.65 million/year program saving 20,000 m³/day costs $0.50/m³ saved; at half the yield, $1.00/m³. Calculation: `3650000 / (saving × 365)`. Scope: Gross program spending per saved unit; not a ratepayer bill or a net benefit estimate. ### F11 · Calculated · An explicit carbon threshold An illustrative ceiling of 0.5 kg CO₂e/m³ requires a grid intensity of about 0.132 kg CO₂e/kWh or lower for the 3.8-kWh/m³ option. Calculation: `0.5 / 3.8`. Scope: An analytical threshold, not a regulatory limit or user policy. ### F12 · Calculated · A modest lift is not free Lifting one m³ through 100 m at 80% efficiency takes about 0.341 kWh, before pipeline friction. Calculation: `1000 kg/m³ × 9.81 m/s² × 100 m / (0.80 × 3600000 J/kWh)`. Scope: Simplified hydraulic work; the actual alignment and pumps are unknown. ### I01 · Inference · Test a portfolio before committing to all-desal The evidence supports testing conservation and reuse first while preserving a seawater option for the remaining dependable gap. Evidence: [S01](https://documents1.worldbank.org/curated/en/476041552622967264/pdf/135312-WP-PUBLIC-14-3-2019-12-3-35-W.pdf#page=58), [S03](https://www.epa.gov/sites/default/files/2018-01/documents/potablereusecompendium_3.pdf#page=124), [S04](https://www.ocwd.com/gwrs/frequently-asked-questions/), [S06](https://www.waterboards.ca.gov/board_decisions/adopted_orders/resolutions/2017/rs2017_0004.pdf#page=2), [S08](https://santabarbaraca.gov/government/departments/public-works/water-resources/water-system/water-sources/desalination). Scope: Conditional synthesis. The 20/60/20 split is illustrative, not optimized or approved. ### I02 · Inference · Reuse and brine dilution can compete Diverting treated effluent into reuse can reduce water available to dilute a colocated desalination discharge. Evidence: [S13](https://waterboards.ca.gov/water_issues/programs/ocean/desalination/docs/dpr.pdf#page=34). Scope: Mass-balance inference from the panel’s co-discharge discussion; the fictional city has no designed outfall. ### U01 · Unknown · The inputs that can reverse the ranking No local measurements establish permanent savings, eligible wastewater, seasonal load, product quality requirements, hydrogeology, marine mixing, grid connection, land, delivery alignment, costs or approvals. Scope: These missing inputs prevent an engineering, legal or procurement recommendation. ## Recommendation trails ### R1 · Build the portfolio before the plant. Test 20,000 m³/day of sustained savings and 60,000 m³/day of reuse, then investigate a 20,000 m³/day residual supply. Preserve the option to expand desalination if the first two resources do not materialize. Evidence claims: C01, C02, C04, C08. Assumptions: A01, A02, A03. Calculations: F03, F08, F09. Supporting source union: [S03](https://www.epa.gov/sites/default/files/2018-01/documents/potablereusecompendium_3.pdf#page=124), [S04](https://www.ocwd.com/gwrs/frequently-asked-questions/), [S06](https://www.waterboards.ca.gov/board_decisions/adopted_orders/resolutions/2017/rs2017_0004.pdf#page=2), [S09](https://research-hub.nlr.gov/en/publications/cost-and-energy-metrics-for-municipal-water-reuse-2/). Additional background: [S01](https://documents1.worldbank.org/curated/en/476041552622967264/pdf/135312-WP-PUBLIC-14-3-2019-12-3-35-W.pdf#page=58). Counterargument: A city with little remaining waste or scarce, highly committed effluent may gain very little from this sequence. An urgent shortage may require parallel project development rather than waiting for one option to finish. What would change the conclusion: If eligible post-conservation effluent reaches 100,000 m³/day at 80% recovery, reuse plus savings could eliminate the residual. If only 37,500 m³/day is eligible, reuse yields 30,000 and the residual rises to 50,000. High confidence in the need to test; low confidence in the illustrative split. ### R2 · Buy dependable water, with an outage plan. If seawater must supply the entire annual-average gap, 90% utilization implies about 111,000 m³/day of nameplate capacity. Storage, parallel trains and independent power still determine whether the city gets water during an outage. Evidence claims: C03, C06, C07. Assumptions: A02, A05. Calculations: F01, F02, F04. Supporting source union: [S02](https://www.energy.gov/sites/default/files/2017/12/f46/Seawater_desalination_bandwidth_study_2017.pdf#page=33), [S05](https://www.sdcwa.org/carlsbad-desalination-project-crews-complete-construction-of-10-mile-pipeline/), [S08](https://santabarbaraca.gov/government/departments/public-works/water-resources/water-system/water-sources/desalination), [S09](https://research-hub.nlr.gov/en/publications/cost-and-energy-metrics-for-municipal-water-reuse-2/), [S10](https://iea.blob.core.windows.net/assets/e4a7e1a5-b6ed-4f36-911f-b0111e49aab9/WorldEnergyOutlook2016ExcerptWaterEnergyNexus.pdf#page=30). Additional background: [S03](https://www.epa.gov/sites/default/files/2018-01/documents/potablereusecompendium_3.pdf#page=124). Counterargument: A larger nameplate does not protect against a shared intake failure, power outage or red tide. A plant used mainly in drought may have high insurance value even when its delivered-water cost is high. What would change the conclusion: A peak-day rather than annual-average requirement changes the sizing problem. A three-day complete outage at this full target requires 300,000 m³ of stored or alternate water before any safety margin. High confidence in the arithmetic; dependable yield remains unproven. ### R3 · Make the power contract part of the water case. Full-target SWRO uses 138.7 GWh/year in this screen. A $0.10/kWh change moves its water cost by $0.38/m³. Cleaner power lowers electricity emissions, while capital and marine impacts remain. Evidence claims: C03, C04, C11. Assumptions: A04, A05. Calculations: F04, F05, F06, F11. Supporting source union: [S02](https://www.energy.gov/sites/default/files/2017/12/f46/Seawater_desalination_bandwidth_study_2017.pdf#page=33), [S03](https://www.epa.gov/sites/default/files/2018-01/documents/potablereusecompendium_3.pdf#page=124), [S09](https://research-hub.nlr.gov/en/publications/cost-and-energy-metrics-for-municipal-water-reuse-2/), [S10](https://iea.blob.core.windows.net/assets/e4a7e1a5-b6ed-4f36-911f-b0111e49aab9/WorldEnergyOutlook2016ExcerptWaterEnergyNexus.pdf#page=30), [S11](https://www.epa.gov/system/files/documents/2025-01/using-egrid-to-determine-emissions.pdf#page=3). Counterargument: A low annual emissions factor does not prove low marginal emissions at the hours the plant operates. Renewable certificates alone do not establish physical hourly supply or eliminate lifecycle impacts. What would change the conclusion: For an illustrative 0.5 kg CO₂e/m³ electricity-emissions ceiling, the factor must be about 0.132 kg CO₂e/kWh or lower. Expensive delivery or a complex reuse train can also narrow the energy advantage. High confidence in sensitivity; grid, alignment and treatment choices are unknown. ### R4 · Treat marine feasibility as a decision gate. Commission the intake, outfall and ecological evidence before treating seawater as an available supply. Read the intake panel’s recommendations with the regulator’s critique attached to them. Evidence claims: C09, C10. Assumptions: A06. Calculations: F07. Supporting source union: [S07](https://waterboards.ca.gov/water_issues/programs/ocean/desalination/), [S12](https://waterboards.ca.gov/water_issues/programs/ocean/desalination/docs/2025/final-ssi-panel-report-with-memo.pdf#page=1), [S13](https://waterboards.ca.gov/water_issues/programs/ocean/desalination/docs/dpr.pdf#page=34). Counterargument: Subsurface intakes can reduce impacts, but geological yield, scale, land and construction conditions matter. Conversely, expense alone does not prove that an option is infeasible. What would change the conclusion: A demonstrated intake yield, acceptable site-specific discharge performance, and an applicable approval pathway could make desalination viable. A protected habitat, poor mixing, or inadequate intake yield could rule out this site. High confidence that the gate matters; no site feasibility finding. ## Retrieval limitations - EPA’s large compendium exceeded the web viewer limit; the complete public PDF was downloaded and relevant pages inspected locally. - The SDCWA web viewer returned 403; a public HTTP retrieval succeeded and its body text was inspected. - An attempted USGS terminology source could not be retrieved and is not included or relied on. - S09 is limited to the institutional abstract; no claim is made to have audited the paper’s full methods.