Seattle City Light 2016 ANNUAL REPORT | Audited Financial Statements 36 THE CITY OF SEATTLE—CITY LIGHT DEPARTMENT NOTES TO FINANCIAL STATEMENTS AS OF AND FOR THE YEARS ENDED DECEMBER 31, 2016 AND 2015 - 36 - In 2015, actual net wholesale revenue was $24.7 million less than budgeted due to an unusually warm and dry winter which yielded lower-than-normal hydro generation volumes, coupled with low wholesale energy market prices. Hence, net transfers of $24.7 million were made to the operating cash account during the year. Interest income of $1.3 million was earned on the RSA. The RSA ending balance was $91.0 million at December 31, 2015, and no surcharges were in effect during 2015. The RSA at December 31, 2016, and 2015, consisted of cash from the following sources: ($ in millions) 2016 2015 Rate Stabilization Account Beginning balance 91.0 $ 114.4 $ Surcharge revenue 4.4 - RSA interest income 1.2 1.3 Operating revenue (5.5) (24.7) Ending balance 91.1 $ 91.0 $ RSA transactions are recorded in accordance with GASB Statement No. 62 Codification of Accounting and Financial Reporting Guidance Contained in Pre-November 30, 1989 FASB and AICPA Pronouncements. The regulatory deferred inflow of resources rate stabilization unearned revenue account at December 31, 2016, and 2015, consisted of the following: ($ in millions) 2016 2015 Unearned revenue - Rate Stabilization Account Beginning balance 66.0 $ 89.4 $ Surcharge revenue 4.4 - RSA interest income 1.2 1.3 Operating revenue (5.5) (24.7) Ending balance 66.1 $ 66.0 $ The initial $25.0 million transfer from the Contingency Reserve Account to the RSA in May 2010 is not included in the Rate stabilization unearned revenue balance, and is not available to be transferred to current revenue in the event that net wholesale revenues are less than the budgeted amount. The Contingency Reserve Account was established in 2005 with proceeds that had been deposited in the Bond Reserve Fund, which was replaced with a surety bond.