Aquatic weed identification is the first step in treating your problem

 Eurasian watermilfoil

Eurasian watermilfoil

     What’s below the surface of your lake or pond certainly plays a part in how everything looks above the surface. Aquatic weeds are a natural part of your pond’s ecosystem. At the same time, when growing excessively, they can block sunlight for other plants, increase sedimentation, reduce fish habitat quality, and promote harmful algae blooms under certain conditions. Aquatic weed identification doesn’t take long – and doing it early can help you choose the right management option and keep your pond or lake healthy and beautiful.

Aquatic weed identification tips

     There are a number of aquatic weeds to be aware of. When you visit our aquatic weed identification tool, your first step is to determine where the weeds are growing – on the surface (floating), fully below the surface (submersed), or growing in water but most growth is protruding above the water (emersed or emergent).

     From there, you can determine the type of weed you have. By looking at photos, you can identify whether you have a common problem aquatic weed such as these submersed plants:

  • Curly leaf pondweed – Common in the north, this pondweed has leaves roughly 1½-2 inches long and about ¼ inch wide with a characteristic undulating leaf margin (edge). It tends to die back in the early summer but grows excessively and creates nuisance conditions in the spring.
  • Hydrilla – This multi-branched invasive weed can also grow with floating fragments. Its dark green, serrated leaves look like small blades arranged in whorls of four or more around the stem.
  • Milfoil – The Eurasian non-native species is a common northern invasive weed. The weed forms of surface canopies of generally reddish stems with multiple branches having gray/green feather-like leaves arranged in whorls of four.

To use the aquatic weed identification tool, go to

The impact of what’s growing in your pond

     Remember, your pond is an ecosystem that changes based on many factors including temperature, oxygen levels, rainfall, and what’s growing below the surface. When the density of aquatic weeds and/or algae gets too high, the pond’s ecology can change dramatically. The fish population could be stunted and in extreme cases, fish population levels may decline, as oxygen levels get too low. Be familiar with the different types of weeds common to your area so you can identify what species are common and how to manage them effectively.

Mark Heilman is Senior Aquatics Technology Leader for SePRO Corporation. As a blogger for, he shares his knowledge and passion about aquatic ecology and protecting our water from aquatic invasive species.