Deep summer signals the time to be on the water. Whether you're boating or swimming, the lakes and ponds of the Adirondacks have few aquatic equivalents in the country for freshwater enthusiasts. In recent years Adirondack waters have been under a growing siege by aquatic invasive species. Headlines about this summer's AIS included news of didymo, spiny waterflea and milfoil. Another species is leading a quiet march into the region: water chestnut. A single plant may not seem threatening, starting as a small, floating rosette of leaves; but, over time, a multitude of plants numbering in the thousands will result in acres of plants that create a virtual carpet on the water's surface, halting access to boating, swimming, and fishing.