Snorkeling presents a cheap approach, with minimal logistics needed and requires minimal skills as well as offering an enjoyable activity in the water.
I describe the methods I have used in removing Variable Leaf Milfoil from the shallows of Lake Arrowhead (York County, Maine) while snorkeling. The lake has a lot of silt, so some of the information includes techniques to avoid stirring up the silt. (Note: I only do this on our shorefront as the entire lake is heavily infested without any chance of being eradicated.)
Equipment needed
Required
Optional
Aqua shoes example
Dive flag example
Small dive flag that attaches to snorkel example
Spare bathing suit and shirt
Wet suit (if very late in season)
Small 'barge' to carry markers, hand nets, trash, and place to place removed plants.
Not required
Fins
Skills required
Ability to swim (in case you get out of depth).
Snorkeling - this is easily learned. If you are new to snorkeling here is how to start:
Obtain a face mask and a snorkel with a purge valve. The purge valve allows you to blow water out of the snorkel, with a small puff of breath.
Get into the water.
Put the mask on, making sure to keep your hair out of the way.
Take a breath and hold it.
Put your face into the water. If water comes in, tighten the strap until you have a decent seal.
Attach the snorkel so that the mouthpiece reaches your mouth nicely.
Put the mouthpiece into your mouth, close your teeth onto it and your lips over the rim.
Put your face back into the water and breathe normally though the snorkel.
Your mask will likely mist up, but there is a simple solution. Let a little bit of water into the mask - it acts like a windshield wiper, by tilting your head about, the water clears the mask.
Some people do not realize that you can take the snorkel below the water surface. Take a breath, and dive down deep enough for the snorkel to go below the surface. You may hear water running into the snorkel. Come back to the surface and then give a short blow, out your mouth - into the snorkel. It blows the water out and you can then take air in again through the cleared snorkel. Practice floating face down and clearing water out the snorkel with puffs of air.
Once you have mastered clearing the water, you can take relaxed deep breaths and swim about with your face in the water indefinitely. You now have access to the best way of viewing aquatic plants!
Equipment explanation
The old T-shirt is to prevent your back from getting sunburnt. Don’t skip this.
Small dive flag attached to snorkel is very good for increasing your visibility.
The dive bag has a handle and an opening and is for collecting the weeds you will be harvesting.
No fins: Fins stir up too much silt, and they really are not needed anyway puttering along in the shallows.
Towel and spare bathing suit: once you leave the water change into dry clothing ASAP. If you intend going back in the water, get into the dry spare swimsuit, and hang the wet one to dry.
Temporary plant maker: I carry a small weight attached to a small float on a belt that I wear while I snorkel. If I find something important (such as a new suspicious plant) I can drop the marker at the location. I can then obtain a better marker and replace the temporary one without losing the location.
Aqua shoes: if the water body is rocky, or has abundant clam shells, or you just don't like touching things with your feet, get some aqua shoes.
The small 'barge' is something that floats and can hold things, it could be a kayak, an inflatable tube, I use something that may have been a car trunk liner. Attach a cord to it for pulling it along with you, and have a small anchor attached to another cord so you can leave it near where you are working.
Rules
Get a boat ride or kayak to the location if it is more than 500m (⅓ of a mile) from your starting point.
Do not tie things (cords to attach tools, pull a barge, etc.) to yourself. Always hold anything tethered by a cord/rope in a hand so that you can let it go when you get tangled up in it.
If the location has boat traffic, have a boat/kayaker loiter on the lakeside of where you are snorkeling or place a dive flag out, but do not rely on it to keep boaters away.
When you hear a boat motor lift your head and find it. If it is nearby, stand up so they can see you.
Never try to swim under docks, logs or other items. A belt or a bit of clothing can easily get snagged and prevent you from surfacing.
If you approach a shadow, find out what is casting the shadow. It could be a dock, boat or stump.
Pop your head out and look about every few minutes. One can easily lose direction and sense of position when underwater.
Watch out for fishing lures, hooks and line. If you have a suitable container, collect lures very carefully as there may be fish hooks embedded in them.
Wash your gear well to remove any fragments or seeds.
Stop if you are cold or tired.
Technique
I usually hold the dive bag (open) with my left hand and my right hand grabs plants and pushes them into the dive bag.
If there is a lot of silt:
Move slowly, the murky water behind you will catch up if you stop.
When you pull a plant out, pull it out to the side or back under you so that the disturbed silt goes away from you.
If the dive bag is full, lift it from the water slowly so the water can drain, or else you risk breaking the mesh.
Milfoil specific tips
Follow the plant down to the roots and grab the roots. You will hear them tearing out.
Be prepared, the plants will often break. When that happens try for the roots.
Expect to also collect some other species of plants that get tangled with the milfoil.
Expectations
Clearing aquatic plants by hand is iterative. You have to cover the area a bunch of times before you get it all.
Do the math, estimate the area you can cover, multiply that by the number of people snorkeling and compare that to the area that is infested. If you can’t cover the area in one season you may not be achieving anything.