A warm winter and a dry spring and summer combined to produce a big jump in BC Hydro power exports this year.

Electricity exports to the U.S. jumped by 73 per cent in the first eight months of 2015 compared to the same period last year, according to export data from Statistics Canada.

BC Hydro says the warmer winter decreased residential customer demand for electricity in B.C., leaving enough water in the Columbia and Peace River reservoirs that their combined volume reached record highs by the end of March 2015. That allowed for more generation from Mica dam on the Columbia River, which recently had a fifth and sixth turbine added to bring it up to maximum design capacity.

"These exports also supported the management of the obligations under the Columbia River Treaty, which provide for increased releases of water from the Canadian Columbia basin when the U.S. basin finds itself in severe drought conditions, as it did in the spring and summer of 2015," said BC Hydro spokesperson Simi Heer. "Ultimately, the increased release meant additional generation at Mica, which resulted in more energy available for export."

The Columbia River Treaty was signed by Canada and the U.S. in 1964, and its flood control mandate is set to expire in 2024. Energy Minister Bill Bennett has argued that the treaty should be renewed with an increased annual payment from the U.S., to reflect the value of controlling the river on the Canadian side for flood control and irrigation for agriculture in Washington state.

The increase in electricity sales was a bright spot for B.C. exports, the value of which fell 22.2 per cent from January to August, due mainly to falling natural gas prices.

Electricity prices also fell during that period, so the 73 per cent increase in exports resulted in only a 32.2 per cent increase in value. Decreases in gas and electricity prices are related to greatly increased shale gas production in the U.S., which is used for power production as well as heating fuel.