I have tested a LIDAR to detect the surface of water. It turned out the water needs to be dirty; i.e, there needs to be particles in the water which can reflect the laser beam of the LIDAR. For clear water, the laser beam went straight through.
If you want to test if your water will work with a LIDAR, you can guess it by using a small laser pointer. If you can see the laser dot on the surface of the water, there is a very good chance LIDAR will work too.