Hydrilla verticillata (lakeweed)

Background – The Lake House

My wife’s parents live on the Tennessee river. We have for years gone there and played on the water. Swimming, boating, fishing enjoying the view and whatever else people might do at the lake.

Hydrilla verticillata, lakeweed
This is an image of the lake weed in the winter when it is less prevalent. If I remember I will get some summer photos next summer out on the water. It can be seen that it captures trash as well creating an ugly viewshed. Even the Canadian geese have avoided swimming where this plant is present.

The Problem – Lakeweed (Hydrilla verticillata)

I’ve previously mentioned that I am an environmental guy. This last summer I became aware of a lake problem in my in-laws backyard. Lakeweed is an aquatic plant from Asia (why do the bad invasives all seem to be from Asia?). It grows under the water unseen until it reaches the surface and the rapidly spreads to cover the surface. This dense growth inhibits water recreation, can increase water pH, blocks sunlight to native plants and can even disrupt fish and plant species diversity within an ecosystem.

Lakeweed is able to grow at depths of 45′ and reach the surface. It can tolerate some salinity and it is incredibly difficult to eliminate in eastern North American freshwater systems. Biocontrol has been attempted though it is still too early to determine if the biocontrol will be successful. Chemical control is available but involves filling the entire water system with chemicals and treating for a decade.

If you read my post about Hemlock Wooly Adelgid then you understand I am not the biggest fan of biocontrol. In the instance of lakeweed I am for anything that works. This plant threatens the entire freshwater aquatic ecosystem of the region and a significant portion of the economy around water recreation and the barge transportation industry.

The Solution – Farming Biomass

While I am really unhappy with this particular invasive plant everything I found in the literature (a short search on google scholar) was focused on eliminating the plant. The methods of eradication are both expensive and longterm and may have drawbacks. I would like to propose an alternate solution to the lakeweed problem, farming.

Hydrilla was introduced in the 1950s to Florida and initially it was farmed. Then it got out of control and became a pest. Since that time the government has made it illegal to sell the plant because of how invasive it is considered. Fast forward to modern times it seems that we are using an outdated approach to address the problem. We are still doing the man can control nature system. This approach while doable is not the best approach. Consider the levy system in New Orleans …nature won. What about Fukushima? Nature won again. Kudzu? Nature. There are many examples where man tries to tame nature only to great disaster when nature wins or man wins too well.

The shift in thought is a new way of looking at the problem. Instead of focusing on eliminating the problem perhaps it is better to accept that we have a problem. Accept that it is a huge problem and will be very costly (if it is even possible) to correct. Move a step forward and ask a new question “How can we benefit from a lakeweed problem?”. ¬†Currently aquatic harvesting machinery can cut and collect the plant matter. One of these aquatic harvesters can be purchased for as cheap as $50,000. The next logical step is that the plant matter needs to be collected and removed from the waterbody to prevent clogs etc..

My solution would be to collect this biomass and figure out a way to turn it into biodiesel or burn it to produce electricity. I have not examined the profitability of this proposal but homeowners spending $300-400 three times a year to cut the lakeweed (a 3-4 hour process), and chemically treat around their docks just to gain access to the main channel is not a good solution. A biodiesel production program or electric generation program run by either Tennessee Valley Authority or the Army Corps of Engineers to actively farm the waterways (which they already control).

A program could either significantly reduce the costs of cutting the lakeweed and thus mitigate the cost of remediation. Alternately if the farming can be made profitable then perhaps the plant can be allowed to remain in the ecosystem and regular rotations for cutting can be developed to maximize recreational use, ecological benefits, and profitability.

Conclusion – Work with not against Nature

I think the key concept to get from this is not necessarily the details on generating profit from a disaster (that can probably be accomplished), such as lakeweed, but rather to shift our thinking as a society from trying to fix disasters to a work with nature approach. I think some environmental professionals probably share this view others probably disagree but it is probably a view that should become more common (in my opinion) because it allows for system that works more cohesively together.