PORTLAND — The Pacific Northwest’s abundant, low-cost hydropower has for decades been the envy of other regions, powering local economies by attracting lucrative industries — from the aluminum smelters that produced the skins of World War II fighter jets to the server farms sprouting for the likes of Google, Apple and Facebook. But a recent scandal over hiring practices at the Bonneville Power Administration has exposed long-standing tensions over control of the agency and its economic benefits. The federal utility is self-financed, so it enjoys autonomy unusual among federal agencies. The independence comes from its control of three-quarters of the Pacific Northwest’s electric grid and power sales amounting to more than a third of the electricity used in the region. The power from 31 dams in the Columbia River Basin flows to 140-plus utilities in Washington, Oregon, Idaho and Montana. Some local stakeholders fear the U.S. Department of Energy could use the agency’s hiring scandal as an excuse to centralize decision-making in Washington, D.C., raising Northwest energy rates and hampering the region’s economy. “The risk is that regional ratepayers might be asked to fund things that are not a benefit to the region, or fund things that should be federal obligations,” said Scott Corwin, executive director of the Public Power Council, which represents BPA’s public utility customers.