EPA initiating consultation with federally recognized Indian Tribes to obtain input on the agency’s proposed amendments to the Standards of Performance for new, modified, and reconstructed stationary combustion turbines and stationary gas turbines, also known as the New Source Performance Standards (NSPS) for stationary gas and combustion turbines. In this rulemaking, EPA is proposing that combustion controls combined with selective catalytic reduction post-combustion control technology is the best system of emission reduction to reduce nitrogen oxides (NOx), with limited exceptions.