The best way you can personally impact your local bee population is by cutting off all uses of herbicides, fertilizers, and insecticides. Even if these are sprayed far away from the hive, after the first rainfall the bees will visit the sprayed plants and drink the poisoned water, bringing it back to their hive and killing it in the process. Start at a local level and educate your neighbors and friends and then start expanding the circle. If your space and time permit it, become a backyard beekeeper. Believe me, it is a very rewarding hobby!