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Arguments Against Herbicidal Treatment

Submitted by admin on Mon, 03/28/2011 - 20:31

Several people have made a strong argument for delaying treatment in 2011 in order to develop a thorough management plan for the pond. The DCR's Generic Environmental Impact Report (GEIR) is clear that the starting point for any intelligent pond management program is a thorough management plan, which we don't have. It makes sense for us to think about the issues at Field Pond with a long term perspective. The treatment program we're on now (ie. the herbicide treatments of 2006 & 2008) requires an expensive (~$25K) reapplication every 2-3 years for as far as the eye can see. The DCR paid the first few, and FPWA would have to contribute 1/3 of the cost of the treatment this year. Future years are uncertain.

Some relevant quotes from the DCR's GEIR (Generic Environmental Impact Report):

page 4-89

    An herbicide treatment can be an effective short-term management procedure to produce a rapid reduction in algae or vascular plants for periods of weeks to months. Although long-term effectiveness from herbicide treatments is possible, in most cases herbicide use is considered a short-term control technique.

    The use of herbicides to get a major plant nuisance under control is a valid element of long-term management when other means of keeping plant growths under control are then applied. However, failure to apply alternative techniques on a smaller scale once the nuisance has been abated places further herbicide treatments in the cosmetic maintenance category; such techniques tend to have poor cost-benefit ratios over the long-term.

p 4-116 (about Fluridone)

    Doses >10 ppb are almost always applied for fanwort control, with doses of 12- 15 ppb showing signs of success and doses near 20 ppb providing nearly complete fanwort kill. Unfortunately, at doses approaching 20 ppb, nearly all other submergent vegetation will be impacted as well.

(The target dose on Field Pond was 15-20ppb)

"The Practical Guide to Lake Management in Massachusetts," (http://www.mass.gov/dcr/watersupply/lakepond/downloads/practical_guide.pdf) which is a companion guide to the GEIR document outlines the various problems encountered in managing lakes including problems with algae (which have to do with phosphorous levels), introduced plant species (invasive plants) such as milfoil, and native plant species which can become “invasive plants” (the water lilies might fit in this category). This guide could be invaluable as we look for alternatives to the chemicals. The “Guide” includes numerous (40+ varieties) "Techniques to Manage Eutrophication and Aquatic Plants." The two chemicals used in previous treatments of Field Pond are discussed – Fluridone on pp. 131-133 and Diquat on pp. 123-124. The advantages and disadvantages of chemical controls are outlined in Table 4 on page 36. Also important to look at are the seven “Axioms for the Control of Rooted Plants in Lakes” on pp. 22-23. Those axioms could be the basis of a plan.

Fanwort may be "native" to this country, but the way it has taken over certain ponds has put it in the "invasive" category. Fanwort infestation was apparently the motivating issue for the application of chemicals at Fosters Pond. ( http://www.fosterspond.com) Reading the steps they have taken to manage that pond is very interesting. They have used, and apparently plan to continue to use, herbicides to control some of the invasive plants, but in addition they have a well-thought out plan of control that includes education and information about the use of fertilizers and detergents and signs to make recreational users aware of the potential for bringing in invasives on their boats and clothing. They also have a "winter drawdown" and individual homeowners use techniques such a "hydro-raking." Fosters Pond differs from our situation as it is not a state pond. Also, we are not looking to have a "beach" in our back yard, only a nice, fertile, pond welcoming to wildlife, canoeing, and walking around.

One more caution about using chemical treatment is that the FPWA doesn't represent the broader population which has a valid interest in the pond as a public natural resource. Those who strongly object to the use of chemicals may hold the FPWA accountable for their use if we are the ones who drive the process. If the DCR were to drive the process then the FPWA is only one of the interested parties.