Salmon Street Springs is the most famous fountain in Portland, Oregon. It is located in Tom McCall Waterfront Park at the end of, aptly enough, Salmon Street.
The fountain is regulated by an underground computer, which toggles between the three phases of the fountain. In the first setting, a tiny spray covers the central area. This setting is popular with little kids, because they can run through the water without fear of getting hurt. In the second, three circles of water jets in the middle shoot straight up. The closer the jets are to the outside, the lower they go. This creates an image resembling a wedding cake. This arrangment is a bit more dangerous; the central jet shoots with the force of a fire hose. Finally, in the third setting, water jets around the perimeter of the fountain arc inwards, creating a huge downfall of water in the middle. Although it is fun to stand in the middle and be bombarded by all of jets, this is not recommended for little kids.
It is rumored that the three phases represent morning, noon, and night, but I can't find any symbolism. If you know what it is, please let me know.