Schedule Page: 102 Line No.: 2 Column: a

Overthrust is indirectly owned by the MountainWest Pipelines Holding Company which is in turn 100% owned by The WIlliams Companies, Inc

Schedule Page: 114 Line No.: 2 Column: c

In 2025, Total Reported Revenues of 76.7 million includes $29.065 MM attributable to Leased Transportation capacity that is not part of Overthrust’s system pursuant to 119 FERC ¶ 61,069, at P 40 (2007). In addition, approximately 21% of Overthrust’s overall costs are allocable to the Leased Transportation capacity.

Schedule Page: 114 Line No.: 2 Column: d

In 2024, Total Reported Revenues of 75.4 million includes $29.065 MM attributable to Leased Transportation capacity that is not part of Overthrust’s system pursuant to 119 FERC ¶ 61,069, at P 40 (2007). In addition, approximately 21% of Overthrust’s overall costs are allocable to the Leased Transportation capacity.

Schedule Page: 220 Line No.: 6 Column: f

Inventory in account 164.1 represents the balance of pipeline owned gas which the pipeline intends to sell or transport. Pipeline owned gas is reported under the inventory method.

Schedule Page: 234 Line No.: 7 Column: k

CTD DESCRIPTION			DEFERRED TAX ACCOUNT			12/31/2025 Balance
PROPERTY, PLANT, & EQUIPMENT			190			$	62,294
REGULATORY LIABILITIES			190			3,130,732
OTHER ACCRUED LIABILITIES			190			1,303,288
190 TOTAL						$	4,496,314

Schedule Page: 262 Line No.: 6 Column: s

Use tax is distributed to various accounts based on the accounts coded on the originating invoice.

Schedule Page: 274 Line No.: 3 Column: k

CTD DESCRIPTION			DEFERRED TAX ACCOUNT			12/31/2025 Balance
PROPERTY, PLANT, & EQUIPMENT			282			$	7,996,002
282 TOTAL						$	7,996,002

Schedule Page: 276 Line No.: 3 Column: k

CTD DESCRIPTION			DEFERRED TAX ACCOUNT			12/31/2025 Balance
REGULATORY ASSETS			283			$	511,534
DEFERRED CHARGES & OTHER ASSETS			283			198,506
283 TOTAL						$	710,040

Schedule Page: 278 Line No.: 1 Column: a

FERC GAS TARIFF SECTION 33

Schedule Page: 278 Line No.: 2 Column: a

FERC GAS TARIFF SECTION 33

Schedule Page: 278 Line No.: 3 Column: a

FERC GAS TARIFF SECTION 14.6

Schedule Page: 278 Line No.: 4 Column: a

Balance reflects Overthrust’s excess deferred income taxes (EDIT) resulting in the reduction in the federal corporate income tax rate under Tax Cuts and Jobs Act of 2017 (TCJA)

Schedule Page: 300 Line No.: 10 Column: h

In 2025, Total Reported Operating Revenues of $76.7 million includes $29.065 MM attributable to Leased Transportation capacity that is not part of Overthrust’s system pursuant to 119 FERC ¶ 61,069, at P 40 (2007). In addition, approximately 21% of Overthrust’s overall costs are allocable to the Leased Transportation capacity.

Schedule Page: 300 Line No.: 10 Column: i

In 2024, Total Reported Operating Revenues of $75.4 million includes $29.065 MM attributable to Leased Transportation capacity that is not part of Overthrust’s system pursuant to 119 FERC ¶ 61,069, at P 40 (2007). In addition, approximately 21% of Overthrust’s overall costs are allocable to the Leased Transportation capacity.

Schedule Page: 300 Line No.: 10 Column: j

Of the total reported volumes, 16,859,730 is attributable to Leased Capacity

Schedule Page: 300 Line No.: 10 Column: k

Of the total reported volumes, 3,617,730 Dth is attributable to Leased Capacity

Schedule Page: 304 Line No.: 3 Column: a

Capacity leased to Rockies Express Pipeline as noted on page 213

Schedule Page: 332 Line No.: 1 Column: a

Delivery Points:

MAP 281 - Kanda/Col

Schedule Page: 358 Line No.: 6 Column: (d)

Enterprise shared service costs are allocated to franchises via specific or general methods. Specific allocations are based on metrics that bear a reasonable correlation to the delivery of services, for instance some human resource services costs are allocated based on employee headcount. General allocations are based on "Modified Massachusetts" formula (MMF) which is determined by the proportion of three components: net revenues; gross property, plant and equipment; and gross payroll.

Schedule Page: 358 Line No.: 12 Column: (d)

Payroll and non-payroll charges for the benefit of the operating area that are not specific to a franchise are allocated to franchises in the operating area via specific or general methods. Specific allocations are based on metrics that bear a reasonable correlation to the delivery of services, for instance some human resource services costs are allocated based on employee headcount. General allocations are based on "Modified Massachusetts" formula (MMF) which is determined by the proportion of three components: net revenues; gross property, plant and equipment; and gross payroll.

Schedule Page: 358 Line No.: 13 Column: (d)

Employees' direct assignment payroll and non-payroll charges recorded to a specific work order for the benefit of the Transmission, Power & Gulf Operating Area that are not specific to a franchise are allocated to franchises included in the operating area via general allocations based on "Modified Massachusetts" formula (MMF).

Schedule Page: 358 Line No.: 18 Column: (d)

Salt Lake City, Utah building rent is allocated based on employee labor hours.

Schedule Page: 358 Line No.: 23 Column: (d)

Houston, Texas Williams tower building rent is allocated based on employee labor hours.

Schedule Page: 358 Line No.: 24 Column: (d)

Common systems hardware and software costs are allocated via general allocations using "Modified Massachusetts" formula (MMF).

Schedule Page: 358 Line No.: 16 Column: d

MountainWest shared services costs are allocated to MountainWest Pipeline, LLC, MountainWest Overthrust Pipeline, LLC, White River Hub, LLC, and nonregulated companies via specific allocations for pipeline companies based on miles of pipe and general allocations for the other companies based on "Modified Massachusetts" formula (MMF).

Schedule Page 518 Line : 6 Column a

Operator Balancing Agreement allocations

Schedule Page: 518 Line No.: 25 Column: a

Operator Balancing Agreement allocations

Schedule Page: 520 Line No.: 20 Column: c

This amount includes 16,859,730 Dth of Leased Capacity volumes which are not subject to the Annual Charge Adjustment (ACA). The total volume subject to the ACA is 374,300,675 Dth.

Schedule Page: 520 Line No.: 20 Column: d

This amount includes 10,301,146 Dth of Leased Capacity volumes which are not subject to the ACA. The total volume subject to the ACA is 94,869,203 Dth.

Schedule Page: 520 Line No.: 2 Column: b

Footnote to Instruction 5:

Overthrust does not bundle sales and transportation services.

Footnote to Instruction 7:

All quantities of gas were subject to Commission regulation.

Footnote to Instruction 9:

Overthrust does not have gas storage.

Schedule Page: 520 Line No.: 29 Column: c

Other Deliveries Includes						Dth
Change in Storage Inventory						3,659
M&R, Mains, &Misc. Fuel						13,035
Total						16,694

Schedule Page: 520 Line No.: 29 Column: d

Other Deliveries Includes						Dth
Change in Storage Inventory						3,659
M&R, Mains, &Misc. Fuel						3,566
Total						7,225

Schedule Page: 521 Line No.: 4 Column: e

Gas used for M&R Fuel. Applies to all other columns on this line.

Schedule Page: 521 Line No.: 34 Column: e

“Net excess or (deficiency)” balances are refunded or collected in-kind through Overthrust's “Gas Use, Lost or Gained and Unaccounted-for Gas-Reimbursement and Tracking” provision (§33) of the General Terms and Conditions of Overthrust's FERC Gas Tariff. Applies to months 2 & 3 also.