Northern California natural gas capacity: the utility's 2026 report shows a thin reserve on the 1-in-10 winter peak day for 2026-27, with a wider reserve in later years

By Sam Strong, Vice President of Business Development, Discovery Energy. Technical review by Tara Dugger, Chief Operating Officer. Updated October 2026.

Key takeaways

Which parts of the record fall inside the five metros?

System context: PG&E's section of the 2026 California Gas Report describes one gas system in 37 counties, "with high concentrations" of customers in the San Francisco Bay Area and the Sacramento Valley, and gives no county list or customer count by county.¹ The design day, resource and demand figures are therefore the most local the record has for all five metros, and each metro's section below says what the record adds locally.

PG&E's system-wide figures and local items, by whether they fall inside the five metros (OMB delineation). Source: 2026 California Gas Report; PG&E storage page; Census Bureau place-by-county file.¹³⁶⁷

San Francisco-Oakland-Fremont, CA

Counties: Alameda, Contra Costa, Marin, San Francisco and San Mateo. PG&E said it has high concentrations of customers in the San Francisco Bay Area; the report states no share of PG&E's customers for this metro, so the system-wide figures apply.¹ PG&E's page on its storage fields says the Los Medanos field is located in Contra Costa County, and the report says the CPUC approved PG&E's proposal to retain it in D.23-11-069.³⁶

For existing gas-fired generation (not new load), EIA's September 2026 inventory lists these generator records that list natural gas: Alameda County 19 records with 888.3 MW of total net summer capacity; Contra Costa County 26 records with 3,341.9 MW; Marin County none; San Francisco County 9 records with 16.4 MW; and San Mateo County 3 records with 7.6 MW.⁷ The California ISO queue lists no active gas generation project in the five counties, EIA lists no planned gas-fired generator there, and no Federal Energy Regulatory Commission pipeline notice since January 1, 2025 names them.⁷

System context: the report says Valero announced in April 2025 that it would decommission its Benicia refinery by the end of April 2026; Benicia is in Solano County, outside all five metros.⁴⁷

San Jose-Sunnyvale-Santa Clara, CA

Counties: San Benito and Santa Clara. The report gives no customer share or county list for PG&E here, so the system-wide figures apply.¹ The report lists the municipality of Palo Alto, in Santa Clara County, among the wholesale customers that receive gas transportation services from PG&E; its own gas system is not analysed in the record read and is a stated gap.¹⁷

EIA's September 2026 inventory lists 57 generator records that list natural gas in Santa Clara County with 1,395.6 MW of total net summer capacity and none in San Benito County (existing generation, not new load).⁷ The California ISO queue lists one active natural gas project in the two counties: Los Esteros Critical Energy Facility Expansion in Santa Clara County, 120 MW, with a current on-line date of September 2023, a date that has already passed and that is not a filing-confirmed service date.⁷ EIA lists no planned gas-fired generator in the two counties and no FERC pipeline notice names them.⁷

Sacramento-Roseville-Folsom, CA

Counties: El Dorado, Placer, Sacramento and Yolo. The report gives no customer share or county list for PG&E here, so the system-wide figures apply; it does say PG&E's customers are concentrated in part in the Sacramento Valley.¹ SMUD owns and operates a pipeline connecting the Cosumnes combined-cycle plant and three cogeneration plants to PG&E's backbone system near Winters, California, which the Census Bureau places in Yolo County; the report says the peak gas load of SMUD's units is approximately 171 MMcf per day, and the average load about 96 MMcf per day (calculated from PG&E's 2026-27 total demand, the peak is 4.3% of that day's demand).⁴⁷ PG&E said its Pleasant Creek storage field is in Yolo County and that the sale to another owner was completed on April 24, 2026.³

EIA's September 2026 inventory lists these generator records that list natural gas (existing generation, not new load): Sacramento County 14 records with 1,088.5 MW of total net summer capacity; Placer County 7 records with 254.6 MW; El Dorado County 2 records with 4.2 MW; and Yolo County none.⁷ The California ISO queue lists no active gas generation project in the four counties (SMUD's own interconnection queue was not located and is not established), EIA lists no planned gas-fired generator there, and no FERC pipeline notice names them.⁷

A note to PG&E's supply tables says its figures include Southwest Gas Corporation and Tuscarora deliveries in the Lake Tahoe and Susanville areas; the report does not say which counties, and South Lake Tahoe is in El Dorado County, so Southwest Gas's service in the metro is a stated gap.¹⁷

Modesto, CA

Counties: Stanislaus (population 557,719 in 2025¹⁴). PG&E's gas tariff title sheet lists Stanislaus County among the counties in which PG&E operates, and its Preliminary Statement lists the county in its table of counties served.¹³¹⁴ The report gives no customer share or county list for PG&E here, so the system-wide figures apply.¹ The tariff says PG&E serves gas in all or portions of 39 counties and the report says 37; the record does not reconcile the two counts, and neither document says whether another gas utility serves part of Stanislaus County.¹¹³

EIA's September 2026 inventory lists 24 generator records that list natural gas in Stanislaus County with 841.0 MW of total net summer capacity (existing generation, not new load).⁷ The California ISO queue lists no active gas generation project in the county, EIA lists no planned gas-fired generator there, and no FERC pipeline notice since January 1, 2025 names it.⁷

Stockton-Lodi, CA

Counties: San Joaquin (population 823,815 in 2025¹⁴). PG&E's gas tariff title sheet lists San Joaquin County among the counties in which PG&E operates, and its Preliminary Statement lists the county in its table of counties served.¹³¹⁴ The report gives no customer share or county list for PG&E here, so the system-wide figures apply.¹ The tariff says PG&E serves gas in all or portions of 39 counties and the report says 37; the record does not reconcile the two counts, and neither document says whether another gas utility serves part of San Joaquin County.¹¹³

EIA's September 2026 inventory lists 12 generator records that list natural gas in San Joaquin County with 864.3 MW of total net summer capacity (existing generation, not new load).⁷ The California ISO queue lists two active gas generation projects in the county: Tracy Combined-Cycle Power Plant (145.0 MW, current on-line date April 2027) and Tracy - Additional Capacity (20.0 MW, current on-line date May 2012, a date that has passed).⁷ The April 2027 date is a queue date and not a filing-confirmed service date, no filing in the record read confirms a service date or a gas supply arrangement for the project, and it is not counted as new gas load. EIA lists no planned gas-fired generator in the county, and no FERC pipeline notice since January 1, 2025 names it.⁷

How much spare gas capacity does Northern California have on the coldest day?

PG&E said its design day standard is based on the 1-in-10 year design day scenario, and that the supply values in its Table 25 are calculated under a 1-in-10 year design day but are still used as supply projections for a 1-in-90 year abnormal peak day (APD) scenario.² Its Table 25 lists these lines for the whole PG&E system.²

PG&E's Table 25, whole system, MMcf per day, per PG&E. Source: 2026 California Gas Report, Northern California section.²

PG&E said projected resources are less than the sum of storage withdrawal and firm flowing supply because its system cannot simultaneously accommodate all flowing supplies and all storage withdrawals.² Its Table 26 lists total demand on a 1-in-10-year peak winter day.²

PG&E's Table 26, whole system, MMcf per day, per PG&E; EG is at the 90th percentile for December through February under 1-in-10 cold and dry hydro conditions. Source: 2026 California Gas Report.²

The report does not state a reserve margin. Discovery Energy compares the two tables, both PG&E's whole-system figures for a 1-in-10 winter peak day, as an illustration:

Illustrative reserve on a 1-in-10 winter peak day, calculated from PG&E's Table 25 line 6 and Table 26 (total demand; without EG means core plus noncore non-EG). Formula: (resources minus demand) divided by demand. Whole PG&E system, not allocated to any metro. Discovery Energy calculation, not a PG&E figure.²

The 2026-27 reserve over total demand is 3.7%, below the 5% threshold that Discovery Energy's outlook scale treats as a thin margin; PG&E's EG demand is 1,194 MMcf per day in 2026-27 and 882 in 2027-28, which is why the calculated reserve widens. PG&E's abnormal peak day core demand with the climate change modifier, 2,809 MMcf per day for 2026-27, is 67.9% of the same year's projected resources.²

What is driving new natural gas demand?

PG&E forecasts that Northern California electric generation gas demand will decrease by 18% in 2030, 32% in 2035 and 71% in 2040 compared with 2026 forecasted throughput.⁴ PG&E also said that if more data center capacity comes online than is forecasted, it could result in even higher gas demand; the report cites the California Energy Commission as reporting almost 23.3 GW of data center capacity requests in California or within the California ISO, with almost 15.9 GW in Northern California. Those are electric capacity requests, not by county, and they are not a documented gas load.⁴

The record searched shows no documented new gas load with a filing-confirmed service date in the 13 metro counties. The California ISO's public queue report lists three active gas projects in the counties: Los Esteros Critical Energy Facility Expansion (Santa Clara County, 120 MW, current on-line date September 2023, a date that has passed), Tracy Combined-Cycle Power Plant (San Joaquin County, 145 MW, current on-line date April 2027, a queue date with no filing-confirmed service date, so not counted) and Tracy - Additional Capacity (San Joaquin County, 20 MW, May 2012, a date that has passed); EIA's September 2026 inventory lists no planned gas-fired generator in them; and Federal Register notices of the Federal Energy Regulatory Commission since January 1, 2025 name none of them.⁷ SMUD's and PG&E's own interconnection queues, state air permit records and California Energy Commission siting records were not located by script and are not established.

Are upgrades arriving in time?

The sections of the report read describe no new pipeline or storage capacity project for the 2026-27 winter. PG&E said the CPUC approved in D.23-11-069 its proposal to retain the Los Medanos storage field, and that the sale of the Pleasant Creek field in Yolo County was completed on April 24, 2026.³ PG&E said the 2027-28 and 2028-29 resource values in Table 25 are those in its 2027 General Rate Case and are subject to change pending the CPUC's approval.² The proceeding on PG&E's peak day supply standard (A.24-07-020) could not be retrieved by script and is listed as a manual download.

Who gets gas first in a shortage?

PG&E said its tariffs contain Emergency Flow Order noncompliance charges designed to cause noncore market customers to either reduce or cease their use of gas.² PG&E's Gas Rule 14 (the sheet saved is dated October 2020) says PG&E may interrupt or reduce delivery of gas in the event of projected or actual capacity constraints, and that when supply is insufficient and deliveries to core customers are threatened it may divert gas supply from noncore end-use customers to core end-use customers, with Emergency Flow Order provisions deemed to apply.⁵ On the backbone transmission paths, the rule says all firm service at all receipt points on a defined path is treated equally, with pro rata allocation of nominations if necessary.⁵ Tariff exposure to Emergency Flow Order charges is not an assessed penalty; the record shows none assessed.

Winter and market context

Context only, as of October 2026. It does not set the outlook level and makes no prediction of outages. Its sources are listed separately under Market and weather sources and are refreshed on the publication date.

National layer: NOAA's Climate Prediction Center said on October 15, 2026 that its November 2026 to January 2027 outlook gives an elevated likelihood of above-normal seasonal precipitation amounts for much of California and the Southwest, in a discussion that names regions and not counties, and that the probability of at least a strong El Nino continuing through January to March 2027 is 80%.^B1 The U.S. Energy Information Administration (EIA) said on October 6, 2026 that it expects U.S. natural gas inventories to enter the winter heating season 2% above the previous five-year average, that prolonged periods of cold weather could increase withdrawals beyond its forecast, and it lists U.S. liquefied natural gas gross exports of 15 billion cubic feet per day in 2025, 18 in 2026 and 19 in 2027.^A1A2

Regional layer: EIA's Pacific storage region (California, Oregon and Washington) held 297 billion cubic feet of working gas in the week of October 16, 2026, according to EIA's weekly table, which gives no five-year comparison.^C1 The nearest regional price EIA publishes is its California citygate series: $2.98 per thousand cubic feet for July 2026, the latest month on its table, and $5.79 for February 2026, a price context that is never evidence of a capacity constraint.^C2 Winter notices from the pipelines on the map are not established: PG&E's Operational Flow Order notice archive and the postings of GTN and Ruby, the interstate pipelines connecting to PG&E's Redwood Path at Malin, Oregon, were not located by script.³

Policy context

Context only, as of October 2026; it does not set the outlook level, a factor or a trigger. Items are stated as their sources state them. Sources are listed separately under Policy sources.

The Bay Area Air Quality Management District (the Air District) page for its building appliance rules (Regulation 9, Rules 4 and 6) says the rules include zero NOx emissions standards with future implementation dates beginning in 2027, 2029 and 2031, depending on size and equipment type, and apply upon burn out of current equipment; the district covers nine Bay Area counties, which include the San Francisco-Oakland-Fremont metro counties and Santa Clara County. The page says the Air District's Board of Directors will consider changes to Rule 6 for water heaters on November 4, 2026; the changes, if approved, provide for some exemptions to the zero-nitrogen oxides standard (proposed, not adopted).⁹

In Rulemaking 24-09-012 on long-term gas system planning (filed September 26, 2024), the CPUC Decision 25-12-042 of December 18, 2025 designated initial priority neighborhood decarbonization zones, selecting census tracts in these metro counties: Alameda 25, Contra Costa 14, San Francisco 3, San Mateo 17, Santa Clara 9, San Benito 2 and Sacramento 13.⁸ A ruling of August 31, 2026 in the proceeding says the CPUC issued Decision 26-07-030 on July 10, 2026, establishing the application process for the neighborhood decarbonization pilot program created by Senate Bill 1221; the proceeding remains open.¹⁰

What is the outlook for Northern California gas capacity through 2029?

Discovery Energy rates the outlook for Northern California (San Francisco-Oakland-Fremont, San Jose-Sunnyvale-Santa Clara, Sacramento-Roseville-Folsom, Modesto and Stockton-Lodi) natural gas capacity through 2029 as Elevated (confidence: Medium): PG&E's own tables, compared by Discovery Energy, show a 3.7% reserve over total demand on the 1-in-10 winter peak day in 2026-27, below the 5% thin-margin threshold, with no fix approved or scheduled for that year and with PG&E's figures covering its whole system. Documented risk factors: none beyond the base level. Three developments would change the assessment: the CPUC's decision on PG&E's 2027 General Rate Case and on its peak day supply standard, which fix the resource values behind Table 25; PG&E's winter 2026-27 operating notices and the 2027 California Gas Report update, with new Tables 25 and 26; a California ISO queue entry or filing that ties a Northern California data center or gas-fired project to gas service with a service date.

Outlook levels, from least to most concern: Stable, Watch, Elevated, High, Severe. Levels describe the public record of capacity and supply risk; confidence is reported separately. They are qualitative assessments, not forecasts of outages.

What should Northern California facilities check now?

• Tariffs and charges, through a utility audit. Confirm each account is on the right rate class and tariff, and that riders, demand charges and capacity-related charges are billed correctly. Over 70% of the clients Discovery Energy has audited were billed incorrectly. An audit verifies tariffs and charges and recovers overcharges before winter costs rise.
• Which service. Confirm whether each site is a core or noncore customer of PG&E, or served by another gas utility such as Palo Alto or Southwest Gas, and read the interruption and Emergency Flow Order terms in the current approved tariff.
• Backup plans and fuel. Check that alternate-fuel and curtailment plans are current and feasible, and that fuel inventories and resupply arrangements are in place before December.
• Upcoming proceedings. Track the CPUC's decisions on PG&E's 2027 General Rate Case and peak day supply standard, and PG&E's 2027 California Gas Report update.

Frequently asked questions

Related case studies

Discovery Energy publishes gas capacity case studies for other metros, using the same method and outlook scale.

• Southern California natural gas capacity case study (outlook: Elevated)
• Las Vegas natural gas capacity case study (outlook: Elevated)
• Portland area natural gas capacity case study (outlook: Elevated)
• Salt Lake City area natural gas capacity case study (outlook: High)

All gas capacity ratings by U.S. metro

Notes

1. PG&E, Northern California section of the 2026 California Gas Report (joint report of the California gas and electric utilities), PDF 44 (Introduction), PDF 30 and PDF 18 (supply table notes and wholesale list); metro counties from metro_counties.csv; classification in northern_california_metro_classification.csv. Utility statements. [NCA-01, NCA-02, NCA-36, NCA-37] ↩
2. Same report, PDF 68 to PDF 70 (design day standard; Tables 25 and 26 and notes; curtailment text). Utility statements. The reserve shares are run by code from PG&E's two tables and are in northern_california_calculations.csv (illustrative, a Discovery Energy calculation and not a PG&E figure): 146 MMcf per day, 3.7%, of 2026-27 total demand; 3.5% of 2026-27 resources. [NCA-03 to NCA-18] ↩
3. Same report, PDF 94 to PDF 96 (interstate pipelines, Baja and Redwood Path capacity, storage); PG&E's Redwood Path is 66.9% of Redwood plus Baja firm capacity and 47.6% of 2026-27 total demand by code (illustrative; two pipelines feed the path). [NCA-22 to NCA-29] ↩
4. Same report, PDF 51 to PDF 53 and PDF 63 (demand, SMUD, data centers). Utility statements. [NCA-30 to NCA-35] ↩
5. PG&E, Gas Rule No. 14, Capacity Allocation and Constraint of Gas Service, Cal. P.U.C. Sheet 36448-G (effective October 28, 2020; PDF 4, 6 and 20). A utility tariff approved by the CPUC; the sheet may have been superseded. [NCA-19 to NCA-21] ↩
6. PG&E, natural gas storage page (Los Medanos entry). Utility statement. [NCA-26] ↩
7. California ISO Public Queue Report (report run October 26, 2026), EIA-860M inventory for September 2026 (Planned and Operating sheets, operator-reported), a Federal Register search of FERC notices since January 1, 2025 by county phrase and the Census Bureau 2020 place-by-county file, all filtered by code. A notice that spells a place differently would be missed. [NCA-38 to NCA-63] ↩
8. CPUC, Decision 25-12-042 (Rulemaking 24-09-012), December 18, 2025, PDF 38 and PDF 39. Commission order. [NCA-74 to NCA-76] ↩
9. Air District, Building Appliances rule development page (Regulation 9, Rules 4 and 6). Regional air district. [NCA-72, NCA-73] ↩
10. CPUC, ALJ ruling of August 31, 2026 (Rulemaking 24-09-012), PDF 1. Commission ruling. [NCA-77, NCA-78] ↩
11. Not established, and left out of the page: supply events since January 1, 2020 affecting PG&E (PG&E's Operational Flow Order archive was not located); delivery-point utilization from pipeline postings (not captured; next capture about March 2027); PG&E's cost allocation among customer classes and the current curtailment priorities beyond Gas Rule 14 (the 2027 General Rate Case and A.24-05-004 are manual downloads); the CPUC proceeding on PG&E's peak day supply standard (A.24-07-020); the customer share and county list of PG&E service for each metro; the gas systems of the City of Palo Alto and Southwest Gas; SMUD's and PG&E's interconnection queues, state air permit records and California Energy Commission siting records; and winter notices of GTN and Ruby.
12. Counties of named places are from the Census Bureau 2020 place-by-county file (Winters, Yolo County; Palo Alto, Santa Clara County; South Lake Tahoe, El Dorado County; Benicia, Solano County). [NCA-59 to NCA-63]
13. PG&E, Gas Tariff Book Title Page (Cal. P.U.C. Sheet No. 38510-G) and Gas Preliminary Statement Part A (territory served and county table), downloaded by script from pge.com in October 2026. Utility tariffs approved by the CPUC; the title sheet prints counties in columns. [VA1-ADD-25, VA1-ADD-26, VA1-ADD-27, VA1-ADD-33, VA1-ADD-34] ↩
14. EIA-860M inventory for September 2026, the California ISO Public Queue Report (run October 2026), a Federal Register search of FERC notices since January 1, 2025, run by code for Stanislaus and San Joaquin counties (derived_additions.txt); Census Bureau Vintage 2025 population estimates for the Modesto and Stockton-Lodi metros. [VA1-ADD-28 to VA1-ADD-32, VA1-ADD-35 to VA1-ADD-41] ↩

Market and weather sources

Public web sources saved and hashed on October 25 and October 26, 2026. They are context, separate from the regulatory record cited in the Notes. The Climate Prediction Center issues its seasonal outlook once each month near mid-month; this section is refreshed on the publication date.

1. A1. U.S. Energy Information Administration, press release, "EIA expects a mixed picture for winter fuel costs this year," October 6, 2026. Link ↩
2. A2. U.S. Energy Information Administration, Short-Term Energy Outlook, October 2026 (natural gas storage). Link ↩
3. B1. NOAA Climate Prediction Center, Prognostic Discussion for Long-Lead Seasonal Outlooks, issued October 15, 2026. Link ↩
4. C1. U.S. Energy Information Administration, Weekly Working Gas in Underground Storage, table through October 16, 2026 (Pacific region). Link ↩
5. C2. U.S. Energy Information Administration, Natural Gas Citygate Price in California, monthly. Link ↩

Policy sources

Official sources saved and hashed on October 26, 2026.

1. P1. Air District, Building Appliances rule development page (Regulation 9, Rules 4 and 6). Link
2. P2. CPUC, Decision 25-12-042, Designating Initial Priority Neighborhood Decarbonization Zones (Rulemaking 24-09-012), December 18, 2025. Link
3. P3. CPUC, ALJ ruling of August 31, 2026 (Rulemaking 24-09-012). Link

Sources

1. California gas and electric utilities, 2026 California Gas Report (PG&E Northern California section). Link
2. PG&E, Gas Rule No. 14. Link
3. PG&E, natural gas storage. Link
4. PG&E, Gas Tariff Book Title Page. Link
5. PG&E, Gas Preliminary Statement Part A. Link
6. California ISO, Public Queue Report. Link
7. Office of Management and Budget, OMB Bulletin No. 23-01, Revised Delineations of Metropolitan Statistical Areas, Micropolitan Statistical Areas, and Combined Statistical Areas, July 21, 2023.
8. U.S. Energy Information Administration, EIA-860M Preliminary Monthly Electric Generator Inventory, September 2026. Link
9. U.S. Census Bureau, 2020 Place by County relationship file. Link
10. Federal Register, API search of Federal Energy Regulatory Commission notices by county. Link