The plan to dredge the Matagorda Ship Channel is causing concern among environmental groups. The channel is located in a mercury-contaminated Superfund site in Lavaca Bay, near Port Lavaca and Port O’Connor. The public has a chance to express their opinions and suggest what should be included in the upcoming environmental impact study. However, the deadline for submitting comments to the Corps of Engineers was Monday. Environmental groups are requesting a 60-day extension to allow more time for people to spread the word.