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  • Writer's picturemariagross

WW Patrolling Techniques or How to Hunt for Aquatic Invaders

Updated: Jul 15, 2020

TIMING of the Patrol

  • Calm surface of the water

  • Minimal glare and reflection

  • Water clarity

  • Going out early AM often offers the best day light


  • Check the weather forecast, including wind and wave activity, cloud cover, angle of the sun, and possible change in water clarity

  • Amount of time you have available

  • Take stock of the challenge before you

o How large is the zone to be patrolled?

o How much of it is littoral? (depth maps are helpful)

  • State of your equipment

  • Are you familiar with the procedures? How well can you recognize the native plants? (The better you can do that: the faster the new or invasive plants will be recognized.)

  • Build safety in your outing

o Best not to go out alone

o Wear a PFD

o Be prepared for sudden changes of weather

  • Many eyes make light work!

o Go out with a buddy and divide the labor

o Observations will be more thorough

o Both team members can watch for hazards


Mid July through September is generally the best time of the year to survey. That said, climate warming seems to be shifting that timing to earlier than July and holding later into October.

Prior to July, many aquatic plants are not fully developed. Emergent flowering structures are sometimes needed for plant ID but the flowers do not typically start to develop until July.

Understand that one invasive aquatic plant, Curly Leaf Pondweed is an exception to this rule, usually reaching maturity by late spring to early summer.

Surveys are to be done within the width of the shore’s littoral area. It extends from the shoreline to the depth at which it is no longer possible to see the lake bottom. Very clear sections may support rooted plants at depths of 15-20 ft. Shallow coves may support rooted plants from shore to shore. On the blog you can find a map that illustrates the extent of the littoral areas along Conway Lake’s entire shoreline. Please check your zone on this map and understand where it would be best to patrol.


(Hit Conway Lake Assn ➣ go to “Blog” ➣ go to “All Posts” ➣ choose Maps)

The course your survey takes must take into consideration how wide or narrow the littoral section is. You may be required to go parallel to the shoreline where it is really shallow, then make a perpendicular or bubble like zigzag to cover the change in the lake’s floor. Sometimes the pattern might be a cross-weave from shore to shore inside a narrow inlet.

In areas where the lake bottom drops relatively steeply from the shore a good strategy would be to plot a straight course that is roughly parallel to the shore, with the deep drop on one side of the boat. Then scan towards the shore. It might be necessary to double back for a better viewing of that area closest to the shore.


Collect specimens when a closer look is needed to distinguish a native plant from an invasive one or if you suspect a Look Alike. All you need is a small segment from the top of the plant in question: reach down into the water and snip it off with your fingernail with a clean cut.

  • REMEMBER that many aquatic plants (native and invasive) can spread through fragmentation. Avoid disturbing plants unless a specimen is required. NEVER yank at the entire stalk to break off a piece of it. Avoid disturbing its roots at all costs (should the plant be an invasive!)

  • If you can’t reach the plant in question with your hand then use a small lawn rake (even an extendable back scratcher can work) to gently get at it. Please be sure to follow up and use a small net to scoop up the fragments or seeds in case you have just found an invasive plant (!)

  • Place your specimen in the white tray with water or even a recycled tennis ball container will work to see how the plant floats out its leaves/branches.

  • This is when you can decide whether you want to know what your plant is. Study it right in the boat or take it home and study it there.

  • If you leave the site then be sure to mark your location in several ways to assure its location: GPS image + flagged noodle + grid location found in your Zone map.


Snip off a cross-section of the stem. And study the leaf formation, its edges, and how the leaves/branches are configured.

  • TAKE A SHARP and DETAILED PHOTO of the specimen - This will help what the naked eye can’t see and it will help others when you post your find on the blog.

  • Or use a magnifying lens to see the finer details of the plant

  • Use your laminated plant ID sheets

  • And/or both the DES book for plant identification and the Maine Field Guide to Invasive Plants. Each of these references complement each other.

  • However, if you need further confirmation, please reach out to a patrol leader, or another member of the patrol.


If all of the above does not seem to help to reach a final ID then send a digital photo to Amy Smagula of NH DES. She is their limnologist/exotic species program coordinator and makes herself immediately available to use as a reference and educator when you have exhausted your own resources.


  • The plant’s stem + branches/ leaves that illustrates their formation on the stem

  • Add fruit or flower, if available

  • A cross section of the stem showing number of leaves/branches

  • Include a coin for size contrast.


Cell: 603-419-9325

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