First, look at the Lake St. Clair Lake Level at Current Lake St. Clair Lake Level
Second, measure the clearance from the water to the connected high ground on your property.
Now keep in mind the Army Corps of Engineers forecast indicates the lake could go as high as 578.1 ft.
The Army Corps of Engineers recommends property owners on the canals provide adequate protection 18 inches above the current lake level. If your property is on the lake subject to wave action, then the recommendation is to provide 36 inches above the current lake level.
If the lake level rises to 578.1, determine the high ground on your property that should be connected to achieve the recommended barrier.
If the rising waters and waves are going to potentially breach your seawall, berm, or any other waterfront barrier, "yes," you must sandbag your property. If not, then "no," you do not have to sandbag your property.
The City strongly advises residents to take into account the forecast levels and build an adequate sandbag barrier before high water occurs. It is much easier to install the barrier on dry ground.