I've come upon a reference to another brother (Robert Watt) of our gggfather (Andrew) who emigrated from Ireland about 1850 and was reported to have been "lockmaster at the Soo", most likely before 1900. I've Googled all I can think of and checked the Sault St. Marie library...who might I contact to see if this is true and if they have information on him?

Was he lockmaster at Sault Ste Marie, Ontario or Sault Ste Marie, Michigan? Have you tried contacting the current lockmaster and asking where employment records would be kept? If he was lockmaster in Ontario go to: Sault Ste. Marie Canal National Historic Site of Canada, if Michigan go to: Soo Locks. Also check out Downward Bound, a website for those seeking persons who worked in the shipping industry on the Great Lakes.