I've seen them between Horseneck and Two Bridges. The river is fairly wide and unobstructed so they can boogie on up and down all they want. Above there is too shallow for them with too many blockages. Thank goodness for that.
Although the river borders the preserve, the river itself is NOT part of the preserve so what they are doing is - unfortunatley - perfectly legal. However if you want to report them for disturbing natural resources, below are contact emails.
