(1) Total program baseline and subtotal baselines. Ecology must use the following methods for establishing a total program baseline for this chapter.

(a) Subtotal baselines are calculated individually for each reporter or sector on an annual basis as described in subsection (2) of this section. The total program baseline is the sum of the subtotal baselines. The total program baseline is given in Table 200-1. Ecology may only adjust the total program baseline through rule making as described in subsections (3) and (4) of this section.

(b) Ecology may combine information from multiple sources and use professional judgment to adjust data sets and conform to this chapter when calculating subtotal baselines. Ecology may use the following data sources when calculating subtotal baselines depending on data availability, quality, applicability, and the agency's best professional judgment.

(i) Data reported to ecology under chapter 173-441 WAC;

(ii) Data provided or described in subsections (2) through (4) of this section;

(iii) Data voluntarily provided by covered parties; or

(iv) Data or estimates obtained or made by ecology.

(2) Subtotal baselines for sectors entering the program in the first compliance period. Ecology must use the following methods for establishing subtotal baselines for facilities, suppliers, or first jurisdictional deliverers described under WAC 173-446-030(1) that would meet applicability requirements based on covered emissions from 2015 through 2019. Subtotal baselines are the annual average of covered emissions for each reporter or sector on a mass basis as established in WAC 173-446-040 from emissions years 2015 through 2019. All emissions years are included in the average, including years with periods of closure or curtailment, and years when covered emissions from a covered entity were under the thresholds in WAC 173-446-030(1) as long as at least one emissions year from 2015 through 2019 would have exceeded the applicability requirements described under WAC 173-446-030(1) for the given facility, supplier, or first jurisdictional deliverer. Ecology may elect not to apply all methods in WAC 173-446-040(3) when calculating subtotal baselines since the total program baseline is the sum of the subtotal baselines. For example, when calculating subtotal baselines, ecology may attribute fuel product combustion described in WAC 173-446-040 (3)(a)(ii)(A) to facilities instead of reallocating those emissions to fuel suppliers. Ecology must apply WAC 173-446-040(3) to make sure that each metric ton of emissions is included in the total program baseline and avoid double counting. Ecology must fully apply WAC 173-446-040(3) any time emissions calculations are specific to a given covered party, such as calculating compliance obligations or allocation baselines.

(a) Facilities that are not EITEs. Ecology must calculate subtotal baselines for facilities that are not EITEs, including electric generating facilities reporting under WAC 173-441-120, based on the facility's covered emissions as established in WAC 173-446-040.

(b) EITE facilities. Ecology must calculate subtotal baselines for EITE facilities based on the facility's covered emissions as established in WAC 173-446-040.

(c) Suppliers of natural gas. Ecology must calculate subtotal baselines for suppliers of natural gas based on the supplier's covered emissions as established in WAC 173-446-040. Ecology must use the supplementary reports defined in WAC 173-446-240 for calculations whenever available and adjust covered emissions to account for large customers as described in WAC 173-446-040 (3)(b)(ii).

(d) Suppliers of fossil fuel other than natural gas. Ecology must calculate subtotal baselines for suppliers of fossil fuel other than natural gas based on the supplier's covered emissions as established in WAC 173-446-040. Ecology must use the existing department of licensing based transportation fuel supplier reports previously submitted to ecology for calculations. Ecology may adjust covered emissions from the transportation fuel supplier reports to subtract GHG emissions estimated to be associated with aviation and add emissions associated with fuel products combusted at facilities as described in WAC 173-446-040 (3)(c).

(e) Carbon dioxide suppliers. Ecology must calculate subtotal baselines for carbon dioxide suppliers based on the supplier's covered emissions as established in WAC 173-446-040.

(f) Electric power entities. Ecology must calculate subtotal baselines for electricity importers based on their covered emissions as established in WAC 173-446-040. Ecology will use fuel mix disclosure reports generated by the department of commerce in accordance with RCW 19.29A.060 to identify and catalog all contracted and unclaimed power and methods from WAC 173-444-040 to estimate GHG emissions. Subtotal baselines for electric generating facilities reporting under WAC 173-441-120 will be calculated as specified under (a) of this subsection and are not part of the electric power entity subtotal baseline.

(3) Subtotal baselines for sectors entering the program in the second compliance period. Subtotal baselines for facilities in sectors described under WAC 173-446-030(2) must be calculated based on the facilities' covered emissions as established in WAC 173-446-040 averaged from emissions years 2023 through 2025. Ecology must adjust the total program baseline in Table 200-1 of this section by adding the subtotal baseline for facilities under WAC 173-446-030(2) in a future rule making by October 1, 2026.

(4) Subtotal baselines for sectors entering the program after the second compliance period. Subtotal baselines for facilities in sectors described under WAC 173-446-030(3) must be calculated based on the facilities' covered emissions as established in WAC 173-446-040 averaged from emissions years 2027 through 2029. Ecology must adjust the total program baseline in Table 200-1 of this section by adding the subtotal baseline for facilities under WAC 173-446-030(3) in a future rule making by October 1, 2028.

(5) Subtotal baseline adjustments for new or modified covered reporters. Ecology will not adjust the total program baseline in Table 200-1 of this section for any new covered reporter joining the program under WAC 173-446-060.