2006 Whole Lake Treatment

The 2006 Treatment Summary

If you're new to the lake or this project, read a summary of what has been going on. The 2005 Whole Lake Treatment

Wendy Crowell, Aquatic Biologist with the Minnesota DNR, and James Johnson, local lake ecologist, were present to advise Lake Restoration on the dosage of the herbicide fluridone (SePro's Avast).

This year, three treatments are planned spaced a couple of weeks apart to allow more control of the dosages.

First Treatment, April 24th, 2006

The first dosage went in on Monday, April 24th, successfully. There are no restrictions on the lake even at the initial doses.

Second Treatment, May 5th, 2006

(ppb = Parts Per Billion)

The second dose went in the lake in an effort to build up to our 4 ppb fluridone concentration goal. The first treatment averaged out around 2.5 ppb, and we need the fluridone to be in the lake at 2-4 ppb for 60-90 days to effectively stunt Curlyleaf Pondweed's growth.

You might also notice that we started the treatments later than last year. The temperature-induced stratification of the water (thermocline) worked so well last year that we and the DNR allowed it to stratify a couple weeks longer with the warmer weather. Stronger stratification means less herbicide needed, which also means lower cost. Of course, that means allowing the Curlyleaf to grow a little longer initially, so you might see more of it this year. It is, however, showing signs of being affected by the fluridone.

The Third Dose Was Never Applied

The third dose was never applied, and the concentrations remained at the appropriate levels during the period required.

How Does Fluridone Work?

The fluridone works by bleaching the chlorophyll (the green stuff) in plants. Chlorophyll is where photosynthesis occurs in a plant. Photosynthesis is the process by which sunlight provides the energy that turns into food within chlorophyll. Basically, we are starving the Curlyleaf Pondweed by bleaching its chlorophyll.

By starving the Curlyleaf Pondweed, we are forcing it to focus all of its energy in surviving. If it focuses its energy on surviving, it will have very little, if any, left to produce its turions. Turions are its main reproductive mechanism - they are the little pinecone-like things you might see floating around on the water. There were no turions produced last year.

Remember, our goal is long term. We want to deplete that turion bank buried in the muck. So, we will expect to see more Curlyleaf in the years ahead, but our hope is that it tapers off!

How did last year go?

Following were our goals and their outcomes for 2005:

Goal Outcome

1 Reduced Turion Production Better than expected

2 Less CLPW washing up on beaches Better than expected

3 Improved native plant growth Better than expected

4 Improved water clarity Much better than expected