(1) Each retail supplier must report to the department each year, based on actual and verified activity in the prior year, the following information on its sources and uses of electricity in Washington:

(a) Electricity delivered to retail electric customers;

(b) Purchases or receipts of electricity from declared resources used to serve retail electric customers, by generating facility and fuel type; and

(c) Purchases or receipts of electricity from unspecified sources used to serve retail electric customers.

(2)The following requirements and limitations apply to the reporting of declared resources:

(a) A retail supplier must report an electricity purchase or receipt as a declared resource if the retail supplier was the direct or indirect owner of the generating facility or acquired the electricity in a transaction, supported by an auditable contract trail, in which the buyer and seller specified the source or set of sources of the electricity.

(b) A retail supplier may assign declared resources and unspecified resources to its retail service for purposes of this section using reasonable methods consistent with its business practices. A retail supplier must identify any change in method from the prior year in its report to the department.

(c) A retail supplier may not report a declared resource as a renewable resource if there exists a renewable energy certificate or other instrument representing the nonpower attributes of the electricity and the retail supplier does not own the renewable energy certificate or instrument.

(d) For an electricity product that is an optional product complying with RCW 19.29A.090, a retail supplier may report as a declared resource any combination of renewable energy certificates and electricity that meets the requirements of RCW 19.29A.090.

(3) Each retail supplier must report as an unspecified source any electricity source that was acquired in a transaction where the fuel attribute was not specified by the seller or provider or was not included in the transaction.

(4) A retail supplier that offers more than one electricity product must report the required source information separately for each product. Individual retail customer rate schedules do not constitute separate electricity products unless electricity sources are different.

(5) Each retail supplier must report the information required by this section as annual totals in megawatt-hours.

(6) The department must determine fuel mix percentages for each retail supplier based on the information provided in source and disposition reports. Each retail supplier's fuel mix percentages must reflect, to the extent possible, the declared resources reported by that retail supplier.