This becomes more risky if the owner is not there to check on one of these or to replace the other. The last category is the money bomb. 

They can put in a series of stakes near the water's edge and zig zag fishing line between them at different heights.  Wrap it around the stakes.  But, if a goose gets tangled, it will be injured or die.  Even if Client hates geese, a neighbor could call police or an animal protection group and Client could end up in court.

The repellent uses grape Kool Aid  with no sugar and water and is sprayed on the lawn to discourage the geese.  It is important to mix  enough Kool Aid in a gallon of water to make it strong.  But as soon as it rains, the smell is gone.

 In the Big Buck category,  put up a fence. Or redesign the shore line with a buffer strip 20 ft. wide with tall native plants.  Geese will not push through them.  Leave an opening to the beach or dock and put up a gate that is closed to keep the geese out.