Detroit-area natural gas capacity: no spare supply shown on the main utility's coldest day

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

Metro used: the Detroit-Warren-Dearborn, MI metropolitan statistical area and the Grand Rapids-Wyoming-Kentwood, MI metropolitan statistical area, as the federal government defined them on July 21, 2023. The tariffs of DTE Gas Company (DTE Gas) and Consumers Energy Company (Consumers Energy) each name places in these counties, and SEMCO Energy Gas Company (SEMCO) names Port Huron.¹ Only DTE Gas's tariff names the principal cities of the Grand Rapids metro, so that metro is added on the DTE Gas record.¹¹

Key takeaways

Who serves the Detroit and Grand Rapids areas?

The record names places in both metros, but it does not show which utility serves which place, and most of the supply figures cover a whole utility system.

DTE Gas's tariff territory sheets (issued in 2013) name many Wayne County cities and townships and some townships in Oakland, Macomb and Livingston counties, and name no locality in Lapeer or St. Clair counties. Consumers Energy's tariff territory sheets (issued in 2019) list places in all six metro counties, including Warren, Sterling Heights, Southfield, Troy and Pontiac. SEMCO says it delivers gas in and around Port Huron, among other places.¹

Inside the Detroit metro are DTE Gas's Belle River, Columbus and West Columbus storage fields in St. Clair County, and the places named in the two tariffs in the six counties.³ Inside the Grand Rapids metro are the places named in the two tariffs in its five counties, plus DTE Gas's Grand Rapids load area and design day temperature.¹¹ The federal definition decides which items fall inside each metro.²²

Other items are company-wide figures: DTE Gas's statewide design day, supply and contracts, its Alpena, Upper Peninsula and Traverse City load areas and Six Lakes storage field, and Consumers Energy's system-wide peak day design. DTE Gas assigns no supply or storage figure to the metro, so this page uses the statewide statements for those.

Four points are unclear: which utility serves each place that both tariffs name (the DTE Gas sheets do not list Warren, Troy or Southfield; the Consumers Energy sheets do), which county SEMCO's territory is in, how the Detroit/Ann Arbor load area relates to the metro, and which counties DTE Gas's Grand Rapids load area covers.

Grand Rapids-Wyoming-Kentwood

Counties and utilities. Both DTE Gas and Consumers Energy name places in the Grand Rapids metro, and the record does not show which serves which. DTE Gas lists no locality in Barry County, while Consumers Energy's tariff lists places in all five counties but not Grand Rapids, Kentwood or Wyoming, so the figures below are DTE Gas's.¹¹

Figures for Grand Rapids. The record has a few figures specific to Grand Rapids, but none for supply or storage. DTE Gas's design day load for its Grand Rapids area is 613 MMcf per day in January 2027, 24.5% of the system-wide total by our calculation.²⁵ The record does not say which counties the area covers.

DTE Gas's mean design day temperature for Grand Rapids is -7 degrees F at the end of January (Detroit: -6). DTE Gas said continued population growth in specific areas such as Kent County (major city Grand Rapids) will continue to change its peak-day load.¹¹

What applies from the rest of the page. The record names no station or storage field in the five counties and gives no figure for the metro's share of DTE Gas's customers, so the system-wide figures on this page apply, and the outlook rests on them for both metros.¹¹ The generator-inventory and Federal Register searches under the demand heading were run for the six Detroit counties only and were not run for the Grand Rapids counties.⁹

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

DTE Gas's own plan for its coldest day shows no spare supply.

DTE Gas's design day plan matches supply to requirements. For January it shows 2,507 MMcf per day of flowing and storage supply against 2,507 MMcf per day of requirements including fuel, with unallocated supply of 0.0,. The filing prints no margin line, so the 0% margin is our calculation: 2,507 minus 2,507 is 0 MMcf per day. That is below the 5% reserve that Discovery Energy's outlook scale treats as thin, and the base level of the outlook below rests on it.³

The plan leans on storage. DTE Gas said approximately 63% of its January 2027 peak day supply comes from storage, that a single storage field can account for up to 35% of total system demand on a design day, and that processing equipment at critical storage fields is forecasted to be operating at its maximum capacity, without redundant units at all fields. It did not name the fields. Three of its four storage fields are in St. Clair County.³

DTE Gas also said that it periodically assesses risks to the system and has contingencies in place to address operational challenges on a design day, and that there is no imminent risk to the system. It said its design day assumptions are conservative, with the coldest temperature in each of sixteen regions presumed to occur on the same day.²⁸

For the 2026-2027 plan year it plans to hold approximately 379 MMcf per day (400 MDth per day) of firm transportation for the winter. MDth means thousands of dekatherms, a unit of gas energy. These are company statements.³

The Commission's order approving the settlement, and Staff's testimony, make no finding on design day or capacity.⁵

For the Detroit/Ann Arbor area, DTE Gas's January design day load is 1,497 MMcf per day of 2,498 MMcf per day system-wide, 59.9% of the system total by our calculation.²⁶ The record assigns no supply or storage to the area.²

Consumers Energy's figures are for its whole gas system, and the outlook rests on DTE Gas's figures. Consumers Energy said its winter peak day design is about 3,600 MMcf per day, with at least 49% of its peak day design requirements estimated to come from storage. MPSC Staff said Consumers Energy presented a reasonable and prudent peak day plan, in testimony that is partly confidential.

Its Exhibit A-33, which is in the public copy, shows a total load requirement and total supply of 3,596 MMcf each in the 1/31/2027, 80-degree-day column, with storage and linepack (gas held in the pipelines) at 61% of supply on page 1. This page does not use Consumers Energy's confidential passages or any redacted figures.⁶

What is driving new natural gas demand?

The records searched document no new gas load in the six metro counties.

DTE Gas projects its customer count to grow and expects its energy waste reduction program to offset the higher volumes, with a slight reduction in overall gas demand by the end of its five-year forecast. It names no new load.²

Consumers Energy said its forecast includes new natural gas-fueled electric generation in its service territory, and names no plant, county or service date.⁶

EIA's September 2026 generator inventory lists no planned natural gas-fired generator in Wayne, Oakland, Macomb, St. Clair, Lapeer or Livingston county. A search of Federal Register notices of the Federal Energy Regulatory Commission since January 1, 2025 finds none naming a metro county and a pipeline docket.⁹

The Midcontinent Independent System Operator's interconnection queue (its list of power projects waiting to connect) lists a 1,452 MW natural gas combined cycle project in Livingston County with a requested in-service date of April 1, 2030, and a 616 MW project in Ottawa County (Grand Rapids metro) with a requested in-service date of June 30, 2028. The entries name no gas supplier, so they do not show a gas load.¹³

A FERC notice of August 28, 2026 lists a filing of an interconnection agreement between the Michigan Electric Transmission Company and Consumers Energy for queue project J4160, a 55 MW gas combustion turbine in Ottawa County. The record we read does not show whether Consumers Energy's gas system serves it.¹⁴

Data centers: As of October 28, 2026, we found no gas special contract or pipeline lateral for a data center on the DTE Gas, Consumers Energy or SEMCO systems in the records reviewed.¹² On October 1, 2026 the Commission approved special contracts under which DTE Electric will supply electricity to a Google data center in Van Buren Township, Wayne County, with service expected from December 2027 and maximum load by December 2028. These are electric contracts, and the record we read does not show gas use.¹⁵

Nearby: DTE Electric contracts for a 1,383 MW data center in Saline Township, Washtenaw County, were conditionally approved on December 18, 2025. That is an electric item in a county that is not in either metro.¹⁶

Are upgrades arriving in time?

The public record we read shows no capacity addition with a date and a budget for the metro. In its September 10, 2026 rate case order the Commission adopted the recommendation to approve $2.4 million for DTE Gas's Belle River dehydration unit project, which no party opposed, and to disallow $6 million for the Belle River Unit #8 turbine exchange, because DTE Gas had not shown the project advanced enough to include in rate base at this time. The judge said the dispute was about timing, not necessity, and DTE Gas said completion was planned for March 2027.

DTE Gas said the turbine is needed to move gas in and out of its Belle River, Columbus and West Columbus fields and will exceed the recommended 30,000 hours of run-time during the test year.⁷

DTE Gas renewed 50 MDth per day of ANR Southwest capacity and 17.5 MDth per day of winter Vector Alliance capacity through October 31, 2028, with rights of first refusal that it said apply in the future. By our calculation, that 67.5 MDth per day is 64.0 MMcf per day at the filing's 1.054 MMBtu per Mcf, 2.55% of the January design day and 16.9% of the 400 MDth per day of firm transportation DTE Gas plans to hold for winter 2026-27.⁴

What does this mean for business gas costs?

The record gives no cost figure for capacity by customer class, so none is given here. These are the positions and decisions on file:

• The Commission's October 1, 2026 order says its September 10, 2026 final decision authorized DTE Gas to increase its annual revenues by $149.318 million for service on and after October 1, 2026, against a request of $237.5 million.⁷
• A group of large industrial customers argued for a design day demand capacity allocator aligned with DTE Gas's planning criteria, in place of the average and peak allocator. This is a party's position.⁷
• The approved gas cost recovery settlement bills a supplier of last resort reservation charge to gas cost recovery customers. MPSC Staff noted DTE Gas's firm pipeline reservation charges of $74 million for 2026-2027 are approximately 36% higher than the $54 million of the previous plan year.⁵

Who bears the cost of any future storage capacity work is not decided in the record we read.

Who gets gas first in a shortage?

In a shortage, both utilities' tariffs set an order for cutting back gas to customers, called curtailment.

DTE Gas's tariff (Rule C3.2) sets five curtailment priorities. Priority One includes residential service, plant protection, essential public health and safety uses, and commercial and industrial requirements of 1,250 Mcf (thousand cubic feet) or less per base period month.⁸ Priorities Two, Three and Four cover commercial and industrial requirements above 1,250, 8,334 and 41,667 Mcf, each up to the next threshold. Priority Five is non-residential customers above 41,667 Mcf with alternate fuel capability, for the alternate fuel load only.

Consumers Energy's tariff (Rule C3) treats firm sales and transportation customers equally under five priority categories, with Priority Five curtailed first and Priority One last.⁸

Winter and market context

NOAA's Climate Prediction Center said on October 15, 2026 that its November 2026 to January 2027 outlook gives the highest odds of warmer than normal conditions to the Great Lakes, a discussion that names regions and not counties.^B1 National gas inventory figures say nothing about either utility's system and are not used to set the outlook on this page.²⁷

Winter weather and NOAA's outlook

The table shows heating degree days, a measure of how cold the weather was, from November to March in winters 2023-24, 2024-25 and 2025-26, with each winter's share of the 1991-2020 normal.¹⁷

Heating degree days, November to March, with the share of the 1991-2020 normal in brackets. Source: NOAA ACIS.²³

Detroit. On October 15, 2026, NOAA's Climate Prediction Center gave Detroit, for November 2026 to January 2027 and December 2026 to February 2027, at least a 50% chance of above-normal temperatures, about 33% near-normal and no more than 17% below-normal.¹⁸ The above-normal figure is a floor and the below-normal figure a ceiling.²⁴ These are probabilities for a three-month average, not a forecast of specific days, and a lean toward warmer weather does not rule out cold days.

Grand Rapids. NOAA's outlook for Grand Rapids gives the same probabilities for both periods, and the same limits apply.

What is the outlook for Detroit gas capacity through 2029?

Discovery Energy rates the outlook for Detroit-area and Grand Rapids natural gas capacity through 2029 as High (confidence: Medium): the base level is Elevated, since DTE Gas's own design day plan shows the 0% margin above on its January 2027 peak day, against the 5% that the scale treats as thin, and the record read shows no approved or scheduled fix; two documented risk factors raise it by one step. DTE Gas said there is no imminent risk to its system, and the Commission's order and Staff made no finding on capacity. Documented risk factors: concentration (F1), since DTE Gas said a single storage field can account for up to 35% of total system demand on a design day and that processing equipment at critical storage fields is forecast to run at maximum capacity without redundant units at all fields; the field is not named and the 35% is an upper bound. Expiring supply (F2): DTE Gas renewed 50 MDth per day of ANR Southwest capacity and 17.5 MDth per day of winter Vector Alliance capacity only through October 31, 2028, which is 16.9% of its planned winter firm transportation, by our calculation, against the 10% test for a key contract. No replacement is decided in the record read. The storage share and the St. Clair County storage fields described above are not scored as a separate risk factor. Three developments would change the assessment: DTE Gas's next gas cost recovery plan and its updated design day plan, including any change to the statement that storage processing equipment is at maximum capacity; any DTE Gas project to add redundant processing or storage deliverability and the Commission's action on it, and the end of the renewed pipeline capacity; Consumers Energy's next peak day design exhibits, or a utility figure that allocates supply and storage to the metro.

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's new (as of October 28, 2026)

On September 10, 2026 the Commission denied DTE Gas's $284.1 million request to replace its aging Taggart compressor station, proposed for service in September 2027 to address equipment obsolescence and outages.¹⁹ On October 15, 2026 the Commission disallowed costs in Consumers Energy's gas rate case for storage pipeline replacement projects, finding the plans premature and the timelines uncertain.²⁰ DTE Gas announced on September 10, 2026 that it intends to file another gas rate case in November, according to the Michigan Attorney General's September 11, 2026 release.²¹

What should Detroit-area 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 utility, and which supply arrangement. Confirm whether each site is served by DTE Gas, Consumers Energy, SEMCO or another gas utility, and whether gas is bought from the utility or from a third-party supplier.
• Your curtailment priority. Check each account's monthly requirement against the priority thresholds in DTE Gas's tariff (Rule C3.2) and whether alternate fuel capability is registered.
• 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 DTE Gas's next gas cost recovery plan and any project at its Belle River storage complex.

Frequently asked questions

Related case studies

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

• Milwaukee natural gas capacity case study (outlook: Watch)
• Chicago natural gas capacity case study (outlook: High)
• Lansing natural gas capacity case study (outlook: Elevated)
• Cincinnati area natural gas capacity case study (outlook: Elevated)
• Pittsburgh natural gas capacity case study (outlook: High)

All gas capacity ratings by U.S. metro

Notes

1. DTE Gas Company Rate Book, M.P.S.C. No. 1 - Gas, Territory Served sheets A-16.00 and A-17.00 (issued February 6, 2013), PDF 17 and 18; Consumers Energy Company Rate Book, M.P.S.C. No. 3 - Gas, Territory Served sheets A-12.00 to A-23.00 (issued December 13, 2019), PDF 17 to 23; SEMCO Energy Gas Company, Company Description web page. Tariff territory lists, not customer counts. The federal definition is Office of Management and Budget Bulletin No. 23-01 (July 21, 2023). The Detroit metro counties are Lapeer, Livingston, Macomb, Oakland, St. Clair and Wayne; the Grand Rapids metro counties are Barry, Ionia, Kent, Montcalm and Ottawa. The DTE Gas sheets name townships in Oakland County (Commerce, Highland, Lyon and Milford), Macomb County (Chesterfield and Macomb, and part of St. Clair Shores) and Livingston County (Brighton, Deerfield and Unadilla). The tariffs list territory, not customers, so they do not show which utility serves which place; most figures on the page are company-wide, so they also cover areas beyond the two metros. ↩
2. DTE Gas, revised application in Case U-21889, filed February 17, 2026, witness Chapel, PDF 11, 23 and 45 (customer and volume forecast, peaker load, Exhibit A-5). Utility statements. DTE Gas projects its customer count to grow from about 1.35 million rate schedule customers in 2025-2026 to about 1.39 million by 2029-2030. It said recent changes in the Detroit area reflect changes in peaker load, and that gas-fired generators are modeled using their most recent three years of activity. ↩
3. Same filing, witness Bratu, PDF 124, 130 to 134 and 156 (design day plan, storage, contracts, Exhibit A-15). Utility statements, company-wide. DTE Gas's design day plan shows the same equality of supply and requirements in February and March. Earlier, after the 2013-2014 winter, DTE Gas purchased parking services and improved the Columbus and Belle River storage fields; these are older measures. The margin is our calculation. ↩
4. Same filing, witness Madigan, PDF 54 and PDF 82 (renewed pipeline capacity; the Vector contract). ↩
5. Michigan Public Service Commission, order approving settlement in Case U-21889 (August 6, 2026), PDF 2 and 5; MPSC Staff testimony of Laura Maio (May 7, 2026), PDF 14 and 16. A Commission order and a Staff analysis; neither makes a capacity finding. In the settlement, the supplier of last resort reservation charge is an additional $0.50 per Mcf billed to GCR customers and $0.34 per Mcf billed to GCC customers. ↩
6. Consumers Energy, application in Case U-21887 (public redacted copy, filed December 22, 2025), witness McDonnell, PDF 42, 70, 82 and 84; MPSC Staff testimony of Nyrhe U. Royal (July 15, 2026, public redacted), PDF 17; Commission order of October 1, 2026, PDF 1. Utility statements, system-wide; Exhibits A-17 (PDF 139) and A-33 (PDF 216 and 217) are in the saved public copy, and confidential passages are not. Consumers Energy also said it relies heavily on storage with limited reliance on flowing pipeline supply and limited firm contract capacity on interstate pipelines. Its Exhibit A-33 shows storage and linepack at 57% of supply on page 2 of the exhibit, and its Exhibit A-17 lists a forecast total system peak day load of 3,596 MMcf for winter 2026/27. ↩
7. Michigan Public Service Commission, final decision in Case U-21973 (DTE Gas rate case, September 10, 2026), PDF 61, 62, 99, 274 and 301; order approving tariffs (October 1, 2026), PDF 1. The $237.5 million request included a $74.8 million infrastructure recovery mechanism roll-in. The September 2026 rate case order summarizes parties' arguments about the ten-year Gas Delivery Plan. The Commission's earlier order asked DTE Gas for a ten-year Gas Delivery Plan that considers declining natural gas demand. ↩
8. DTE Gas tariff, Rule C3.2 (PDF 53); Consumers Energy tariff, Rule C3 (PDF 48). ↩
9. EIA-860M inventory for September 2026 (Planned sheet), filtered to the six metro counties, and a Federal Register search of FERC notices since January 1, 2025 by county phrase, computed (``). A notice that spells a place differently would be missed. ↩
10. Not established, and left out of the page: dated supply events since 2020 (none in the filings read; the Staff testimony names only the 2019 polar vortex); which storage fields are at their processing limit; Consumers Energy's confidential passages and any redacted figures; any peak day or capacity figure for SEMCO; which utility serves which place; EGLE air permits, MISO interconnection queue entries and county economic development filings (not scriptable; a news report of a SEMCO data center gas infrastructure plan in 2025 names no county and is a lead only); delivery-point utilization from pipeline postings (not captured; next capture about March 2027); the cost allocation outcome in the DTE Gas rate case beyond the positions above.
11. DTE Gas Rate Book, M.P.S.C. No. 1 - Gas, Territory Served sheets A-18.00 to A-23.00 (PDF 19 to 24); Consumers Energy Rate Book, M.P.S.C. No. 3 - Gas, Territory Served sheets A-12.00 to A-21.00 (PDF 12, 16, 17, 20 and 21); DTE Gas, revised application in Case U-21889, witness Chapel, PDF 23, and Exhibit A-5, PDF 44 and 45; Grand Rapids metro counties from the OMB delineation file (). Tariff territory lists, not customer counts; the sheets are in columns, and the match of cities to counties is general geography, not a quotation. The township counts, the absence of Barry County from the DTE Gas sheets and of Grand Rapids, Kentwood and Wyoming from the Consumers Energy sheets, and the 24.5% share are computed (). Not established, and left out: which utility serves each place; supply or storage for the Grand Rapids area; searches for new gas load in the Grand Rapids counties. DTE Gas's Territory Served sheets list the cities of Grand Rapids, East Grand Rapids, Kentwood, Walker, Wyoming, Grandville, Rockford and Cedar Springs, and township entries in four of the five counties: 16 in Kent, 10 in Montcalm, five in Ottawa and one in Ionia (Otisco). Consumers Energy's tariff (issued in 2019) lists the City of Lowell and eight townships in Kent County. The system-wide figures that apply to both metros are the January 2027 peak day plan with no spare supply, the dependence on storage and the pipeline capacity renewed only to October 31, 2028. ↩
12. Searches of October 28, 2026: EIA-860M September 2026 (11 Detroit and Grand Rapids counties); MISO public interconnection queue; Federal Register FERC notices since July 30, 2026 for the county names; Michigan Public Service Commission order U-21973 and Attorney General releases. Not reviewed: Michigan Public Service Commission e-dockets, EGLE air permits, FERC eLibrary, pipeline portals. ↩
13. Midcontinent Independent System Operator, Generator interconnection queue, public project list (API), dated 2026-09-30, saved 2026-10-28; MISO queue entry J3799: fuelType Gas, facilityType Combined Cycle, summerNetMW 1452.0, poiName BLACKFOOT - MADRID 345.0kV, applicationStatus Pending Revision Approval, studyCycle DPP-2025. Midcontinent Independent System Operator, Generator interconnection queue, public project list (API), dated 2026-09-30, saved 2026-10-28; MISO queue entry J4159: fuelType Gas, facilityType Combined Cycle, summerNetMW 616.0, poiName ROOSEVELT, applicationStatus Active, studyCycle DPP-2026. The Ottawa County project was queued August 13, 2025 and the Livingston County project April 18, 2024. ↩
14. Federal Register / Federal Energy Regulatory Commission, Combined Notice of Filings, Federal Register 2026-17635 (August 28, 2026), ER26-3608-000, dated 2026-08-28, saved 2026-10-28; Federal Register 2026-17635, Combined Notice of Filings, ER26-3608-000. ↩
15. Michigan Public Service Commission, News release, DTE Electric and Google data center contracts, Case U-22058, dated 2026-10-01, saved 2026-10-28; News release, first paragraph. Michigan Public Service Commission, News release, DTE Electric and Google data center contracts, Case U-22058, dated 2026-10-01, saved 2026-10-28; News release, in-service paragraph. ↩
16. Michigan Public Service Commission, News release, DTE Electric contracts for Saline Township data center, Case U-21990, dated 2025-12-18, saved 2026-10-28; News release, first paragraph. ↩
17. NOAA Regional Climate Centers, Applied Climate Information System (ACIS) StnData web service, monthly heating degree days (base 65F) and 1991-2020 normals, November to March of winters 2023-24 to 2025-26, retrieved October 26 to 28, 2026: DETROIT METRO AIRPORT; GRAND RAPIDS GERALD R FORD INTL AP. Sums computed. ↩
18. NOAA Climate Prediction Center, seasonal temperature outlook issued October 15, 2026, shapefiles lead1 (November to January) and lead2 (December to February) from ftp.cpc.ncep.noaa.gov/GIS/us_tempprcpfcst/seastemp_202610.zip, read at each metro's coordinates. The map gives the favored category and the lower edge of its probability band; NOAA's own explanation (Link) keeps near-normal at 33.3% and gives the opposite category the rest, so the above-normal figure is a floor and the below-normal figure a ceiling. At the two metros, for both periods, NOAA gives the chance of above-normal temperatures as at least 50%, near-normal as about 33% and below-normal as no more than 17%. ↩
19. Michigan Public Service Commission, Final order, Case U-21973 (DTE Gas rate case), September 10, 2026, dated 2026-09-10, saved 2026-10-28; PDF page 99. Michigan Public Service Commission, Final order, Case U-21973 (DTE Gas rate case), September 10, 2026, dated 2026-09-10, saved 2026-10-28; PDF page 94. Michigan Public Service Commission, News release, DTE Gas rate case order, Case U-21973, dated 2026-09-10, saved 2026-10-28; News release, Taggart bullet. ↩
20. Michigan Public Service Commission, News release, Consumers Energy gas rate case order, Case U-21981, dated 2026-10-15, saved 2026-10-28; News release, disallowed costs paragraph. ↩
21. Michigan Department of Attorney General, Press release, DTE announces another new rate case, dated 2026-09-11, saved 2026-10-28; Press release, first paragraph. ↩
22. Metro boundaries are the federal government's definition of each metro area, OMB Bulletin No. 23-01 (July 21, 2023). Record items on this page are sorted by whether they fall inside the Detroit or Grand Rapids metro using that definition. Sources: DTE Gas and Consumers Energy tariffs; DTE Gas revised application, February 2026. ↩
23. Heating degree day sums and shares of the 1991-2020 normal were computed from NOAA ACIS monthly data (see note 17). ↩
24. NOAA's Climate Prediction Center outlook was read at each metro's coordinates; the map gives the lower edge of the favored category's probability band, so the above-normal figure is a floor and the below-normal figure a ceiling (see note 18). ↩
25. Grand Rapids area share of DTE Gas's system-wide January 2027 design day load, supporting the 24.5% figure: 613 divided by 2,498 MMcf per day, our illustrative calculation. ↩
26. Detroit/Ann Arbor area share of DTE Gas's system-wide January design day load, supporting the 59.9% figure: 1,497 divided by 2,498 MMcf per day, our illustrative calculation. ↩
27. NOAA's Climate Prediction Center discussion of October 15, 2026 also gives the highest odds of warmer than normal conditions to Southeast Alaska and the upper Mississippi Valley. The U.S. Energy Information Administration 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 (source A1). ↩
28. DTE Gas said its design day assumptions are conservative: minimum storage balances, statewide coldest record temperatures, maximum midstream withdrawal rates and high end-use transportation withdrawal rates occur simultaneously, and the coldest temperature in each of sixteen regions is presumed to occur on the same day. ↩

Market and weather sources

Public web sources saved and hashed on October 25, 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. B1. NOAA Climate Prediction Center, Prognostic Discussion for Long-Lead Seasonal Outlooks, issued October 15, 2026. Link ↩

Sources

1. Michigan Public Service Commission, Case U-21889, DTE Gas Company revised application (February 17, 2026), Staff testimony of Laura Maio (May 7, 2026) and order approving settlement (August 6, 2026). Link
2. Michigan Public Service Commission, Case U-21887, Consumers Energy Company application (public redacted), Staff testimony of Nyrhe U. Royal, and order (October 1, 2026). Link
3. Michigan Public Service Commission, Case U-21973, final decision of September 10, 2026 and order approving tariffs of October 1, 2026. Link
4. DTE Gas Company, Rate Book, M.P.S.C. No. 1 - Gas. Link
5. Consumers Energy Company, Rate Book for Natural Gas Service, M.P.S.C. No. 3 - Gas. Link
6. SEMCO Energy Gas Company, Company Description. 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. Federal Register, API search of Federal Energy Regulatory Commission notices by county. Link