Aquatic Macrophytes

Some people refer to aquatic macrophytes as "weeds" because in many Massachusetts lakes and ponds the plants have grown extremely successfully over the years and have become a hindrance to human recreation. Before adopting a plant management regime, it is a good idea to survey those plants to learn which ones are there and in what density.

Plant Mapping

Instructions on Mapping Aquatic Plants in Lakes and Ponds is available in a Manual by DEP's Rick McVoy.

This method teaches how to map the areal cover of plants, by density, and also how to produce a map of identified plants, using transects and a weed weasel (see photo above) to collect plant samples.

Bathymetric Maps

Before mapping the plants, you may need a bathymetric map of your pond: These maps, showing depth contours, are great as a base map for an aquatic plant survey. Many bathymetric maps are now available for Massachusetts water bodies from Mass Wildlife.

Aquatic Plant Identification

There are several useful guides and keys to identify the plants you may find in your water body:

Aquatic and Wetland plants of northeastern North America (2000)
by Garrett Crow and C. Barre Hellquist.

Through the Looking Glass: A Field Guide to Aquatic Plants
published by Wisconsin Lakes Partnership and the University of Wisconsin-Extension/Stevens Point, is now available through the NALMS Bookstore. Price: $19.96 Members / $24.95 Non-Members + shipping and handling.

How to make a Weed Weasel

For people familiar with the plant survey technique, here are instructions on how to build a "weed weasel", the tool used to sample aquatic vegetation:

weed weasel photoMaterials Needed:

  • 2 garden rakes
  • 2 regular bolts
  • 1 eyebolt
  • 3 nuts
  • several tie-wraps
  • 20-30 feet of line (clothesline is OK)
  • duct tape

Tools needed:

  • drill
  • saw
  1. Saw off the rake handles at 3 feet.
  2. Place the rakes back to back (tape them together with duct tape to hold them tight).
  3. Drill a hole through both handles near the top of the handles, at the middle, and near the bottom.
  4. Place bolts through two lower holes and secure with nuts. Use the eyebolt in the top hole.
  5. Tie the rakes together with tie-wraps between tines.
  6. Tie the line to the yoke part of the weasel and thread through the eyebolt.


The MA Department of Conservation and Recreation offers a Weed Watchers Program where they train local lake groups to monitor their ponds for the presence of exotic invasive species and to develop a removal plan if an infestation is found. You can learn more and sign up for a class on the Weed Watchers web page.