NORTHWEST PIPELINE LLC

Transco - Results of Operations

Variances due to the changes in natural gas prices and transportation volumes have little impact on revenues because, under our rate design methodology, the majority of overall cost of service is recovered through firm capacity reservation charges in Transco’s transportation rates.

Transco has cash out sales, which settle gas imbalances with shippers. In the course of providing transportation services to customers, Transco may receive different quantities of gas from shippers than the quantities delivered on behalf of those shippers. Additionally, Transco transports gas on various pipeline systems, which may deliver different quantities of gas on Transco’s behalf than the quantities of gas received from Transco. These transactions result in gas transportation and exchange imbalance receivables and payables. Transco’s tariff includes a method whereby the majority of transportation imbalances are settled on a monthly basis through cash out sales or purchases. The net cash out activity has no impact on Transco’s operating income.

Revenues increased primarily due to:

•An increase in Natural gas transportation service revenues primarily due to placing the following projects into service:

◦The Commonwealth Energy Connector in November 2025;

◦The Alabama Georgia Connector in October 2025;

◦The Texas Louisiana Energy Pathway in April 2025;

◦The Southeast Energy Connector in April 2025.

The increase in Natural gas transportation service revenues is also due to higher electric power revenue, partially offset by decreases in commodity revenues, short-term firm transportation, and a cash out surcharge (offset in Other operating (income) expense – net resulting in no net impact on results of operations). Electric power costs are recovered from Transco’s customers through transportation rates and are offset in Operating and maintenance expenses resulting in no net impact on Transco’s results of operations.

•An increase in Natural gas storage service revenues primarily due to an increase in rates.

•An increase in Natural gas product sales due to higher cash-out pricing and volumes, which directly offsets in Natural gas product costs resulting in no net impact on our results of operations.

•An increase in Other service revenues due to higher park and loan services.

Operating and maintenance expenses increased primarily due to higher electric power costs and an increase in labor-related costs. Electric power costs are recovered from customers through transportation rates and are offset in Natural gas transportation service revenues resulting in no net impact on results of operations. This was partially offset by lower natural gas fuel expense due to favorable pricing.

Depreciation and amortization expenses increased primarily due to the 2025 depreciation rate change and new assets placed into service.

General and administrative expenses increased primarily due to higher labor-related costs.

Taxes, other than income taxes increased primarily due to higher property taxes related to new assets placed into service.

Other operating (income) expense – netchanged favorably primarily due to lower project feasibility costs and a cash out surcharge (offset in Natural gas transportation service revenues resulting in no net impact on results of operations).

Interest expense was primarily impacted by 2025 debt issuances and a retirement.

Interest income increased due to higher interest income on advances to Williams during 2026.

Allowance for equity and borrowed funds used during construction (AFUDC)increased as a result of higher eligible capital expenditures.