Water Quality Certification Improvement Act of 2023

This bill clarifies and streamlines the process for states and agencies to certify that federally permitted projects (like dams or pipelines) won't harm water quality. It requires certifying authorities to publish clear certification requirements upfront, make written decisions within 90 days based only on specific water quality standards (sections 301, 302, 303, 306, and 307), and explain their reasoning. The changes directly affect project applicants seeking federal permits and state agencies handling water quality certifications. Key mechanisms include setting a strict 90-day timeline for decisions, banning arbitrary delays, and ensuring certifications are strictly tied to established water quality rules.