There has been a very serious issue with Ontario’s lakes shrinking year over year. I was at a friend’s cottage last month and she was pointing out the rock they used to jump off into the lake as kids; it is now at least 10 metres away from the edge of the lake. When this is on a public beach, it just means more beach area. When it is in front of your cottage, however, it is a stickier issue.
The main question is: does your deed give you ownership to the high water mark or to the water’s edge? If you own to the water’s edge, and there is no shore road allowance, then you likely get the new (accreted) land. Otherwise, you may be out of luck – and with a dock on dry land.
If you are thinking of buying a cottage, there are many more considerations than the number of bedrooms and bathrooms. You should see a lawyer who has experience with cottage properties – ideally before you even put in your offer.