Carolyn and Lin - Glad you found the article of interest and has given you some ideas to add one or more to your own yard. Really, once the container is created, it's a breeze to maintain.
Holly - I had my husband cut out two round circular covers out of plywood. I painted them blue (photo of one can be seen in the article). Then I added some chicken wire to the top of the small round pond containers and then just lay the blue top on it at night. During the day, I just roll them over to an area where they are standing on end. I thought about using them for round table tops during the day. And might still do that. The chicken wire... I just remove and roll up and put behind the round ponds during the day. I don't do anything to the smaller water containers as I have no fish in them. I use mosquito dunks instead. Raccoons only bother the containers with fish.
Jill - I had my ponds with fish uncovered for many years, but once the raccoons find the water gardens and the fish .... they return faithfully to check to see if there are more to eat. Even with the covers, I can see little dirty paw prints on the covers the next morning. They know the fish are in there, but they can't move the top off. Too heavy!
If you have a smaller water container, you can cover with just a piece of wood. I'd put a paver or cinder block on top so the raccoons can't move the cover off. They are smart little devils!