Creek water is not going to start algae in might bring something to your tank you don't want in there. It actually took several months for algae to grow in the container. Most people don't want algae in their tank. The tank that I have some algae on the walls is two years old. In some ways I'd love to scrape it all off but I need to leave enough food for my nerite. You will have to be patient and you might request an algae donation from someone as a starter. Here is how one person suggested growing algae. You can use small rocks like a couple of bag of rocks from Petsmart for your small setup:
"Include a rock or plant from another tank that has even a tiny amount of algae on it. Add a few drops of HOUSE PLANT fertilizer to the container., and give it plenty of light. Without plants to compete with it, the algae will soon cover the rocks. Then you can place one at a time in with your obligate algae eating fish/snail for them to clean off. Rotate them in and out of your algae farm, and remember to feed the algae, but sparingly, or you'll make a mess!"