They may need to be touched up thereafter, depending on how they're maintained. It's called a caststone component building system, which can create waterfalls and rock outcroppings on pools, spas and ponds. Customers want the looks and the sounds. Sometimes they want a lot of water sound to help drown out traffic noise. You can create white noise to drown out your neighbor's air conditioner or road noise.
White noise can be a very inexpensive thing to accomplish.