To my understanding, that license allows you to apply Restricted use pesticides, however there are none with an aquatic label. So theoretically you can do work in aquatics now if you like. Dont quote me on that. I hire an aquatics co for one of my properties and IMO its much easier than L&O. They do some hand hand pulling, and selectively spray with backpacks. I believe they charge quite abit more than they need to because they are a niche. Seems like a business with a high profit margin.
In horse country, the town requires the owners to maintain a littoral shelf as a buffer. So a lot of the farms have an aquatics company maintaining the ponds.