The Bureau of Reclamation may on and after September 29, 1989, accept the services of volunteers and, from any funds available to it, provide for their incidental expenses to carry out any activity of the Bureau of Reclamation except policymaking or law or regulatory enforcement. Such volunteers shall not be deemed employees of the United States Government, except for the purposes of chapter 81 of title 5 relating to compensation for work injuries, and shall not be deemed employees of the Bureau of Reclamation except for the purposes of tort claims to the same extent as a regular employee of the Bureau of Reclamation would be under identical circumstances.