Geese tend to walk to their feeding site from water, and rarely fly up over a fence, especially during the "molting" period (mid-June through mid-July) when they cannot fly. A 3-foot chicken wire fence is an effective barrier. Geese like to be able to see around them, which is why you don't see them in the woods or in tall grass fields. Therefore, planting a hedge or leaving a wide swatch of uncut weeds between water and mowed grass creates a natural, low maintenance barrier.
Putting out flags, tying aluminum pie plates along strings, using scarecrows all may help keep geese away from an area until they learn these objects pose no threat. Full bodied swan or coyote decoys sometimes work because geese perceive the decoys as threats. It's important to move decoys periodically or the geese will realize the decoys aren't real.
For an active approach, try walking up to the birds then flapping a tablecloth. Trained dogs are especially effective but need to be used on a long term basis. Costs are a consideration when "hiring" a dog and handler. Loud noises may also work, but geese can adapt to noise. If geese have to spend too much energy avoiding harassment to eat and rest properly, they will go elsewhere.
Geese concentrate wherever people feed them. Feeding encourages birds to stay in areas where they normally wouldn't and build up flock sizes the habitat can't support. The food you feed ducks and geese is not their proper diet. Feeding makes geese less wary of people and lowers natural winter mortality. You may enjoy feeding ducks and geese, but it is in the birds' best interest if you don't.
Some parks have erected signs with "friendly" messages to discourage feeding of geese (and ducks) and have seen a significant drop in feeding. One example of possible text to use: "Keep Wild Things Wild! Please don't feed the ducks and geese. This can cause the birds to lose their natural fear of people and impact their natural ability to survive on their own."
Some people inquire about destroying or taking eggs from goose nests--this only results in the geese to continue to lay eggs, replacing the broken or missing eggs. It is also illegal to destroy eggs of most bird species, including Canada geese.
In some cases, egg addling (shaking) or oiling can stabilize flock size, but these efforts are time consuming and mostly appropriate only for urban areas with concentrated nesting sites. Nests can be difficult to find, even in the most urban areas. Studies show that a flock would fall to only 75% of it's original size in 10 years if 95% of eggs were addled or oiled annually.
Permits are needed to engage in this activity.
Prevention Methods Requiring a Permit
In some areas of Massachusetts, numbers of resident Canada geese and their droppings have overwhelmed homeowners, municipal parks, golf courses, and other property owners and tenants.
Putting up barriers, feeding prohibitions and other such tactics should be tried first in preventing further problems.
If you are still having goose grief, you can pursue hunting and egg addling, both of which though, require permits in Massachusetts. Read.