If all of the houses on your street have a view to the lake and you pay a higher property tax, due to access to the lake, there may be legal options for you. First you need to get the land surveyor records for that property and make sure the trees are in fact on the neighbors property and not on a common public area. Then you would go to the appropriate agency in your township to see what can be done. Take pictures with you. Only if this has no result then I would seek legal advice, if you want to push it that far. Also you may want to try inviting your neighbors over for coffee and sit with them where you usually enjoy your view. Then nicely point out that you use to enjoy such a beautiful lake view until they put the trees there. Then see what they say.
If they own the property and planted the trees on their property, I'm sorry, but there isn't anything you can (legally) do. Perhaps you could talk with them about their trees obscuring your view of the lake and ask if they would be willing to relocate them to another part of their yard, but they don't actually have to say yes and move the trees.