In addition to what Michael Nielsen posted, keep in mind that the blue is probably a whole lot brighter than you think it is.

Most things in the natural world get their apparent colour by selectively reflecting a part of the visible light spectrum, and that almost always includes "contamination" (for want of a better word) by colours other than the predominant one. Green vegetation always has a red component; red flowers usually have some amount of green in them as well.

The lights you are asking about are created by direct emission of a very specific wavelength of light. There is no contamination. No matter how bright that blue light gets, it will always be blue, and since it is "only blue", it will appear less bright than lights that are less intense at the blue wavelength, but has intensity contributions at other points on the spectrum as well. A "white" light that appears to be as bright as the blue will have one-third (or thereabouts) of its intensity in colours you could call "blue", another third in green and yet another third in red.

Now let's say that that white light records as an RGB value of just barely (255, 255, 255). The blue will register as (0, 0, 255)—but if it were possible to record more blue without clipping, it would likely have recorded as something quite a bit higher in the (clipped) blue channel. Let's say (0, 0, 767) just for fun, shall we? (768 is three times 256, so I've lumped triple intensity into one channel.) When that white reflection in the water has trailed away to 127, 127, 127 due to subobtimal reflection angles, dispersion and so on, the neighbouring blue reflection is still motoring along at a captured value of 0, 0, 255 (and would be 0, 0, 383 if your camera could record it).

It's the fact that you have a single colour channel driven into clipping that's the fundamental problem. It records as a maximum value for that channel, but you have no way of knowing what the actual value is (other than to say it's too much). If the light has been designed to register as bright as a white light would have, it needs to be an awful lot brighter in that channel than the white light would have been. And since your eyes don't clip digitally (or knit together the changing patterns of reflections on the water over time), you won't see with the naked eye the same thing the camera sees.