This shows the amount of water chestnut infestation at Route 48 in Ox Creek a couple of years ago.
Oswego Daily News

Herbicides To Be Used Against Invading Water Chestnuts

Starting next week, herbicide will be used to help eradicate water chestnut growth in parts of the Oswego River. Water chestnuts are an invasive weed that grows on the surface of the water on several CNY rivers. These plants create an obstacle to boaters and prevent swimming in many areas along local rivers.

[…]