Pursuant to Docket No. RP12-490

This amount represents the EDIT created by the reduction in the federal corporate income tax rate under TCJA, the decrease in the weighted marginal state income tax rate, and a state income tax adjustment associated with changes in ownership. The timing of the refund of the regulatory liability to rate payers is stated in the Docket No. RP22-1155 rate case settlement. Additionally, as of December 31, 2025, Northwest has $6 million of rate based deferred taxes established as a result of a decrease to the effective state income tax rate. This item will be subject to future discussions and negotiation with our customers in our next rate case.

This amount represents the EDIT created by the reduction in the federal corporate income tax rate under TCJA, the decrease in the weighted marginal state income tax rate, and a state income tax adjustment associated with changes in ownership. The timing of the refund of the regulatory liability to rate payers is stated in the Docket No. RP22-1155 rate case settlement.

Pursuant to Section 14.12 of General Terms and Conditions of Northwest’s Tariff.

Pursuant to Section 14.12 of General Terms and Conditions of Northwest’s Tariff

The 25-year Evergreen incremental revenues and volumes are shown as separate line items although they fall under the TF-1 rate schedule.

Gas of Others Received for Transmission represents scheduled receipt nominations net of in-kind fuel. The volumes shown do not impact the overall page 520 system gas balance because the differences between scheduled receipt nominations and actual physical receipts are captured in the 806 imbalances and are included in the numbers shown on lines 10 and 25 of page 520. The in-kind reimbursements are shown on lines 13 and 14.

Gas of Others Received for Contract Storage represents scheduled withdrawal nominations by others. The volumes shown do not impact the overall page 520 system gas balance because the differences between scheduled storage withdrawal nominations and actual physical storage receipts onto the mainline are captured in the 806 imbalances shown on lines 10 and 25.

Northwest had the following storage quantities at 3/31/2026:

Jackson Prairie Storage			Dth
Contract Storage			2,981,061
System Balancing Gas			1,862,932
Plymouth Storage
Contract Storage			2,217,896
System Balancing Gas			343,032
Customer Boil-off Balance			84,727
Clay Basin Storage
System Balancing Gas			1,724,783

Gas Received as Imbalances reflects the gas recorded (Northwest’s imbalances are cleared through in-kind exchanges and reflects the net change) in account 806 that relates to OBA, Receiving Party, Shipper and Park and Loan imbalances.

Other Gas Withdrawn from Storage relates to system balancing.

Deliveries of Gas Transported by Others represents scheduled delivery nominations. The volumes shown do not impact the overall page 520 system gas balance because the differences between scheduled delivery nominations and actual physical deliveries are captured in the 806 imbalances and are included in the numbers shown on lines 10 and 25 of page 520.

Deliveries of Contract Storage Gas represents scheduled injection nominations by others. The volumes shown do not impact the overall page 520 system gas balance because the difference between scheduled storage injections nominations and actual physical volumes delivered into storage are captured in the 806 imbalances shown on lines 10 and 25 .

Gas Delivered as Imbalances reflects the gas recorded in account 806 that relates to OBA, Receiving Party, Shipper and Park and Loan imbalances and is shown as Gas Delivered to Others.

Other Gas Delivered to Storage relates to system balancing.

The Other Deliveries reflects gas used for purposes other than operating compressor stations plus working gas, change in line pack and gas used in other non-mainline projects.

Any monthly excess or deficiency of gas is refunded or collected in-kind through Northwest’s semi-annual fuel filing process.

The numbers shown on this page include any fuel usage and in-kind reimbursements associated with transmission and storage rate schedules.

The numbers shown on this page are derived by taking the total volume of throughput and allocating it among the three contract categories (i.e. contracts with discounted rates, contracts with negotiated rates, and contracts with recourse rates) based on the percentage of gas transported for each contract type.