Yes, as others have said, Alameda is a very friendly place. You mentioned that you have a dog so walking your dog along the beach front will certainly bring you new acquaintences as will a visit to the dog park.
If you like to get out on the water (Alameda is an island after all) there are rowing and paddling clubs such as the Alameda Dragonflyers, a paddling group with members of all ages and ethnicities. In fact, they refer to themselves as a social club with a paddling problem~
If you like gardening there is a group called the Alameda Backyard Growers who meet up to share information and produce from their backyard gardens and their motto is "grow some, eat some, and give some away -- to the food bank. They donate their excess produce to the food bank for those in need. You don't even have to have a garden to be part of the group. If you like to garden, but don't have a plot of your own, there is always someone who would appreciate your help in their garden.
So there you have it. All kinds of possibilities for you to make new friends. I'm sure it won't take long. Feel free to be in touch if you would like to know more about any of these groups.