It has been growing in Beluga Lake here in Homer since the late 1960s. We had to take samples from the lake as school projects. For a few years they poisoned it and that worked. And they also let high tides fill the lake with sea water. ( It was originally a tidal slough anyway) and a few years ago they had a cool boat with paddle-wheel gizmos that ripped the weeds out of the lake by the dump truck load. BUT they have not done anything in the last couple of years and it is very hard to taxi in some areas without loading up your rudder. And of course more weeds on rudders increases the chances of the weeds being spread.