HOUSTON (Reuters) – Texas authorities on Friday charged 31 people involved in a protest that shut a key Houston oil artery under a state law that makes it a felony to disrupt energy pipelines and ports. The Harris County Sheriff’s Office charged Greenpeace climate change protesters who dangled on ropes from a bridge for most of Thursday, and others who supported them. The group shut a portion of the Houston Ship Channel, the largest U.S. energy-export port, for a day. Those charged include six people not in custody, a spokesman for the sheriff’s office said. All face up to two years in prison under a Texas “critical infrastructure” law that took effect last month. A Greenpeace spokesman declined immediate comment. The Houston Ship Channel on Friday reopened for vessel traffic, the U.S. Coast Guard said, after the last of 11 protesters who had disrupted traffic by dangling on ropes above the key energy-export waterway was removed by police earlier in the morning. A large portion of the channel was closed when protesters attached themselves and banners to a bridge over the waterway to bring attention to climate change during Thursday’s debate of Democratic presidential hopefuls in Houston. Police early on Friday arrested 23 Greenpeace members involved in the protest, with the last removed about 1 a.m. local time by Harris County Sheriff’s officers, said Travis Nichols, a Greenpeace spokesman. The 23 were taken to the Harris County jail in Houston. Briscoe Cain, a Texas state lawmaker whose district includes part of the ship channel, had said the group would be the first to be charged under a recently enacted state law that makes disrupting critical infrastructure a crime. Related CoverageHouston climate protesters charged with violating ‘infrastructure law’: sheriffThe protests had halted movement on a large portion of the Houston Ship Channel, which stretches 53 miles (85 km) from its entrance in the Gulf of Mexico to the Port of Houston. The area affected is home to five major oil refineries as well as chemical and oil-export terminals. Day-long shutdowns caused by fog are typically cleared within a day, a Coast Guard official said on Thursday.