DESCRIPTION: Eurasian watermilfoil is a submersed perennial. It has a long underwater stem that branches profusely when it reaches the surface of the water. Leaves are whorled on the stem at each node, and there are generally four leaves per whorl. Milfoil can winter over in frozen lakes, thrive in warm pond waters, and live in acidic and calcium rich waters, slow moving waters of lakes and ponds and some rivers. Milfoil is found in a variety of sediments, light levels, temperatures, and depths up to 20 feet. Q: What chemical should I use to treat water milfoil? Douglas – Goddard, KS. A: Before we dive into how to treat this aquatic invader, let’s get to know it a little better first. Water milfoil, also known as Eurasian Water Milfoil (Myriophyllum spicatum), is a submersed aquatic plant that’s native to Europe, Asia and northern Africa.