Other Technologies

Why the ABV des 7 chose the burlap as a method of Eurasian Water Milfoil control

The ABV des 7 has reviewed all known methods for the control of water milfoil and concluded the following:

 1. Bubblers

•  Using air bubblers to oxygenate the water has produced inconsistent results    It seems to be only marginally effective in small areas like a pond, but is not realistic or cost- effective for larger areas like a lake    Equipment is expensive.  It also doesn't kill off 100% of the milfoil in an area.  This can leave plants in high boat traffic areas where they can get chopped up by boat propellers.  This leads to the plan continuing to spread by stem fragmentation.

 2. Cutting and harvesting

• Milfoil can be hand cut and removed.  However, it is next to impossible to get all the clippings left over from the process.  Although, this process is cheap and produces immediate results, it tends to increase the rate at which the milfoil will spread. o One lake in particular, had its milfoil infestation increase in size by over 3-fold in a 3-year period.  Part of this increase in milfoil was attributed to a cutting program implemented on the lake.    Running a harvester (a mechanized industrial cutting machine) only trims the milfoil, similar to cutting the grass on a lawn.  It doesn’t actually kill off the plant or remove the roots, so the milfoil will only continue to grow.  Worst of all, although it collects a high percentage of the cut plants, it also leaves a significant number of cuttings behind.    Those cuttings can produce a disastrous effect on increasing the spread of the milfoil.

 3. Rototilling

• Rototilling digs down into the benthic layer and removes the milfoil at its roots.  

However, it causes significant damage to the benthic layer, releases chemicals and sediments from the benthic layer into the lake and still leaves behind a significant number of uncollected cuttings, similar to a harvester.  This process is impractical around rocky lake bottoms

 4. Using SCUBA divers to manually pull or harvest the milfoil

• The use of SCUBA divers (or divers with suction systems) to manually remove milfoil, including its roots can be effective, but is one of the most expensive solutions.  There are companies in the United States that offer this service and many lakes have spent hundreds of thousands of dollars each year per lake, for this service.
  
  
• This service could be more expensive in Canada given that technically any work underwater should be done by commercial divers, which are considerably more expensive. Realistically, this process should be done by experienced personnel to ensure that it is done properly, to limit the spread of clippings This can be a challenging process, given that some bottom conditions can turn up a significant amount of bottom silts during the process, leaving the divers working in zero visibility conditions.

• Weevils are expensive (about $1 US per weevil) and produce inconsistent results.
• A number of lakes in the Sudbury area spent $175,000 on weevils and the process did not work in the end.

http://www.cbc.ca/news/canada/sudbury/weevils-milfoil-sudbury1.368522

• If you only wanted to clear a path from a boat launch to the open lake, we cannot use weevils.

 6. Chemicals

• The use chemicals are illegal in Canada

 7. Non-biodegradable benthic mats

• Non-biodegradable benthic mats are placed on top of milfoil infestations and will kill off the milfoil.
• Permanent benthic mats are not environmentally safe and not a healthy solution for the benthic layer of a lake or river
• There is no advantage to a non-biodegradable benthic mat over a biodegradable one as the non-biodegradable mat need to be removed.

The burlap solution will kill off the milfoil in the first season and the burlap cloth will biodegrade in 1 to 3 years after installation.   However, milfoil can spread back into the area if the fragmentation within the area has not been stopped.  To properly manage the spread of milfoil in a given lake, the milfoil must be removed from the high traffic areas.   This includes both public passage ways and around private docks.  For this reason, Block aid has developed both an automated industrial solution to reduce the cost of installation as well as do-it-yourself dock kits for private docks. The ultimate goal is to be able to repair milfoil damaged fish habitats on a large scale