This action finalizes the residual risk and technology review (RTR) conducted for the Stationary Combustion Turbines source category regulated under national emission standards for hazardous air pollutants (NESHAP). In addition, we are taking final action addressing requirements during periods of startup, shutdown, and malfunction (SSM) and to add electronic reporting requirements. The EPA is finalizing our proposed determination that the risks from this source category due to emissions of air toxics are acceptable and that the existing NESHAP provides an ample margin of safety to protect public health. The EPA is also finalizing our proposed determination that we identified no new cost-effective controls under the technology review that would achieve further emissions reductions from the source category.