RALEIGH, N.C. An Alcoa Inc. subsidiary is appealing a decision by North Carolina regulators who revoked a key certification amid allegations the company intentionally withheld information. Alcoa's appeal attempts to remove a big obstacle to the company's effort to renew its license to operate dams along the Yadkin River for up to 50 years. Alcoa Power Generating Inc. said Friday it didn't withhold material information. A North Carolina Department of Environment and Natural Resources spokesman said the agency received notice of Alcoa's appeal. The state agency's Division of Water Quality last month revoked the certification, saying internal company e-mails showed Alcoa officials expressing concern that downstream waters may not meet state standards.