(1) A utility must report metrics of energy and emissions intensity to the commission on or before June 1st of each year. The report must include annual values for each metric for the preceding ten calendar years. Each value reported must be based on the annual energy or emissions from all generating resources providing service to customers of that utility in Washington state, regardless of the location of the generating resources. When the metrics are calculated from generators that serve out-of-state and in-state customers, the annual energy and emissions outputs must be prorated to represent the proportion of the resource used by Washington customers.

(2) The energy and emissions intensity report shall include the following metrics:

(a) Average megawatt-hours per residential customer;

(b) Average megawatt-hours per commercial customer;

(c) Megawatt-hours per capita;

(d) Million short tons of CO2 emissions; and

(e) Comparison of annual million short tons of CO2 emissions to 1990 emissions.

(3) Unknown generation sources. For resources where the utility purchases energy from unknown generation sources, often called "spot market" purchases, from which the emission rates are unknown, the utility shall report emission metrics using the average electric power CO2 emissions rate described as the net system mix (spot market) in the Washington state electric utility fuel mix disclosure reports compiled by the department pursuant to RCW 19.29A.080. For the resources described in this subsection, a utility must show in the report required in subsection (1) of this section the following:

(a) Short tons of CO2 from unknown generation sources;

(b) Megawatt-hours delivered to its retail customers from unknown generation sources; and

(c) Percentage of total load represented by unknown generation sources.

(4) The energy and emissions intensity report must include narrative text and graphics describing trends and an analysis of the likely causes of changes, or lack of changes, in the metrics.