The Coast Guard created the Coast Guard Marine Safety Inspection Office (MIO) Port Arthur in 1942. It arose from the Coast Guard absorption of the Department of Commerce's Bureau of Marine Inspection and Navigation. In 1976, the MIO combined with the Captain of the Port (COTP) Sabine Pass, forming the Marine Safety Office (MSO) Port Arthur. As a part of the Coast Guard's reorganization into Sectors, MSO Port Arthur became Marine Safety Unit (MSU) Port Arthur in November 2005 under the command of Sector Houston-Galveston. Coast Guard Marine Safety Detachment (MSD) Lake Charles was established in 1976 as a sub-unit of then Marine Safety Office Port Arthur. In February 2001, the MSD was reorganized and established as Marine Safety Unit (MSU) Lake Charles. Under the new Sector organization, MSU Lake Charles continues its longstanding and mutually beneficial relationship as a sub-unit of MSU Port Arthur.
The Commanding Officer of MSU Port Arthur is responsible for carrying out the Coast Guard's homeland security, marine safety, and marine environmental protection missions in a zone of responsibility that includes Southwest Louisiana and Southeast and East Texas. Included in this zone are the Ports of Lake Charles, Louisiana; Sabine, Port Arthur, Orange and Beaumont, Texas; 141 miles of the Gulf Intra coastal Waterway; and 4 Outer Continental Shelf Lease Zones.
Unit personnel inspect U.S. and foreign deep draft commercial vessels, offshore platforms, mobile offshore drilling units, and designated waterfront facilities. They monitor transfer operations involving hazardous materials, detect and respond to waterborne oil and chemical spills, and monitor clean-up operations. They also investigate vessel and personnel casualties and incidents of negligence attributable to licensed or documented Merchant Mariners.
Following the tragic events of 9/11, MSU Port Arthur rapidly transitioned to meet its new amplified homeland security mission.