PORTLAND, Ore. (AP) - Wind power companies facing a springtime shutdown to accommodate a surge of hydropower in the Northwest say the region's main power manager has a conflict of interest, using authority over transmission lines to protect its business interests.

Tuesday's charge from the American Wind Energy Association follows the Bonneville Power Administration's announcement last week that it plans to curtail wind power because of a surplus of energy from hydroelectric dams.

Such a shutdown could cost Northwest wind developers millions of dollars in tax credits.

The Bonneville Power Administration manages much of the region's transmission. It also sells power from dams, much of it to public power districts. A spokesman says the BPA is required to keep those operations separate, and wind power will be curtailed only as a last resort.