AUSTIN — A plan to allow billboards up to 65 feet tall along some Texas highways raised environmental concerns during a public hearing on updating sign regulations enacted in the 1980s.The Texas Department of Transportation has proposed the change, supported by advertising companies, as part of an overhaul of billboard rules, the Austin American-Statesman reported. The Texas Transportation Commission heard public testimony Tuesday, with written comments accepted through July 14. The panel is expected to decide by August on whether to adjust the current 42.5-foot height restriction. “People who agree on little else are unanimous that we don’t need more billboards or taller billboards,” said Katherine Romans, who manages landowner outreach for the Hill Country Alliance, a group devoted to protecting natural resources. The higher limit is necessary because the speed of travel has increased and highways have expanded, said Billy Reagan, president of Reagan Outdoor Advertising, which controls hundreds of billboards in Texas. “We’re a going concern that supports businesses in the state of Texas that generate sales tax in the state of Texas,” Reagan said. Billboard advertising is critical to those businesses making themselves known to the public, he said. Some advertisers have constructed billboards low to the ground to maximize the amount of signage space under the current restriction. The proposal calls for a 25-foot minimum height for billboards, amid concerns about public safety when signs are close to the ground and easily reachable.