June 20, 2009 Special Meeting

Tomahawk and Sand Bar Lakes

Eurasian Watermilfoil Research Project Update

1:00 P.M. Saturday, June 20, 2009

Barnes Town Hall

Ingemar Ekstrom, chairman of the Town of Barnes EWM Committee, welcomed everyone to the meeting and talked about the CBCW activities in recent months. He gave a brief tribute to deceased EWM Committee member Jim Joswick. He also advised the group that the committee received the State of Wisconsin Lake Stewardship Award

1.      Welcome and outline of the meeting agenda

Facilitator: Bob Korth, University of Wisconsin Extension Lakes Team

Bob welcomed the group and asked the group what their expectations were of the meeting.

Input from the group was a series of questions they wanted answered: what are the plans for Sand Bar Lakes? Why aren’t they monitoring the Tomahawk Lake boat landing? What were the results of the treatment?

Update on the research project

2.      Overview of the project design, and herbicide residual results, and well testing results

John Skogerboe, Army Corps of engineers

John gave a Power Point presentation reviewing the actual treatment that was done to Tomahawk Lake in 2008.

·        He showed maps of the treated areas, which was actually a whole lake treatment. The lake was treated at a concentration rate (0.5 mg/L) that was ¼ of the manufacturer’s “label rate” - (2-4 mg/L.)

·        The application was done in early spring for several reasons; Exotic species usually emerge in early spring, many of the native, sensitive species were still dormant at this time, minimal microbial degradation occurs in early spring making the herbicide effective for a longer period.

·        Data collection evaluated the herbicide target impact, changes in lake water quality, and changes in the plant density.

·        Water sampling was done in strategic places on the lake.

·        The concentration of 2,4-D was reviewed and showed that the degradation of the herbicide was unexpectedly slow.

·        2, 4-D was not detected in Sand Bar Lake or in any of the wells tested on either lake.

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Results

·        Much longer exposure times than predicted

·        No detectable EWM as of June 2009, thirteen months after treatment.

·        Unexpected impacts to the native population

·        No additional treatments will be needed in 2009.

Questions from the audience:

?       What was the water quality of Tomahawk Lake area well water after the treatment? Samples were collected from various wells around the lake…no detection of 2,4-D  in any areas around both lakes.

?       Were the samples from shallow or deep wells? Samples were taken from anyone who asked to have their wells tested, we do not have a record of the type of well, but that info can be gathered. Had 2,4-D been detected, well depth and other information would have been collected.

?       How many well water samples were taken? 9-12…not sure. ( Follow-up:  9 wells were sampled.)

3.      Aquatic plant community changes

Aquatic plant Management Specialist Frank Koshere, WDNR

Frank reviewed the impact of the 2,4-D treatment to the other aquatic plants.

·        Pre-treatment biomass samples were collected in 2006 and 2007

·        Post-treatment samples were collected in 2008

·        Results showed that the lakes lost a lot of vegetation…including species other than EWM

·        The impact on native plants was reviewed through a series of slides; the impact of the treatment was surprising in that it did reduce the native vegetation, both in quantity and diversity. This was a surprising results – has not been observed in past projects.

·        There is no EWM present – this is very unusual

·        No statistical change in Sand Bar Lake

·        Future sampling is essential

Questions from the audience:

?       Did the presence of EWM inhibit the growth of native plants? Did not see that in any studies.

?       Would the lake level impact the vegetation? It is a variable that will affect the results.

?       Is it beneficial to have the low lake level? Kind of a neutral…native plants can fluctuate, but EWM is very adaptable also.

Questions as we move forward:

·        Will EWM come back?

·        Will the native plants return?

·        What is the future for Sand Bar Lake?

4.      Water quality changes and statewide herbicide research context

Statewide limnologist Tim Asplund, WDNR

Tim reviewed the water quality changes during the study:

·        Sampling showed that Tomahawk Lake was not as clear during the treatment year as it was in pre-treatment years.

·        The highest chlorophyll concentration of the three year study occurred in October, 2008.

·        Phosphorus levels appear to have remained constant

·        The concentration levels are still relatively normal, but it should be noted that the chlorophyll level did change.

·        Samplings on Sand Bar Lake showed the water quality was similar to previous year’s.

·        There were no significant Oxygen concentration changes in either of the two lakes in the 3 years studied.

·        The Tomahawk and Sand Bar Lakes Research Project is one of nine being conducted in the state of Wisconsin.

·        The toxicity of 2,4-D was reviewed. The application rate and residual concentrations on Tomahawk Lake were well below most toxicity thresholds (e.g. adult and child swimming, drinking water).  The only exception was for irrigation.  (Follow-up:  herbicide residuals were no longer detectable in October 2008 so the irrigation restriction does not apply in 2009).

·        A great amount of money is being spent on the projects, therefore it is important that the results are measured, documented and the risks and benefits are weighed.

Treatment Conclusion: there were some surprises.

Discussion of the next steps for Tomahawk and Sand Bar Lake to 2011

Existing Plan:

2009    Post treatment surveys will continue, no additional treatment of Tomahawk. Aquatic plant management planning efforts commence. 

2010    Post treatment surveys will continue, additional treatment of Tomahawk not yet determined. Aquatic plant management plan finalized.  Lake management plan will be developed for Sand Bar Lake.

2011    Possible treatment of Sand Bar Lake for which a grant will be needed.

Questions from the audience:

?       Do we have to apply for another grant to treat Sand Bar Lake? Yes we do.

Some discussion followed. A member of the audience did not agree that the group was told that another grant would be needed to treat Sand Bar Lake. One attendee verbalized that if Sand Bar is not treated, the EWM will move right back into Tomahawk. Frank Koshere responded that the management of the lakes going forward does need to be planned to ensure that the benefit of the treatment is not lost.

?       Tomahawk Lake is clean right now, why is the public boat landing still open? We don’t want EWM back in, the landing could be a source of re-infestation, Very few people are using the landing, and it is difficult to keep someone at the landing to monitor it all the time. We do have property owners watching it. Because the landing is a public resource, closing the landing is not an option.

?       Would you change the concentration of the 2,4-D in future treatments? Because of effectiveness of the herbicide on Tomahawk, it looks like we could reduce the concentration; use less of the herbicide and save some dollars.

?       Did rainfall levels make a difference in the life of the herbicide? Rainfall would not impact the dilution rate of the herbicide. Other factors probably impacted the dilution rate.

?       When will you know what to do for Sand Bar Lake, best case scenario? You as a group will need to make a decision for your lake…that includes applying for a grant, or getting funds by other means.

Some discussion followed, with several people from the group indicating they thought that the treatment for Sand Bar Lake would start before 2011. Tim Asplund indicated that the DNR is committed to preparing a plan and continuing to work with the group on Sand Bar Lake in 2011. Stephania Strzalkowska also advised the group, that there is money for AIS projects. The Town of Barnes could write a grant for the Sand Bar Lake treatment and the Town of Barnes may also contribute funds. She also advised the group that a grant could be written to specifically monitor the Tomahawk Lake landing next year.

?       If 3 years from now, the EWM is still gone but the native plants do not recover, would you consider still consider the treatment successful? Plant life is changing…watersheds have changed. There is some data that is several decades old. Actually the loss of the native plants would be considered a failure component of the project. However, few of the plants were eradicated…we will watch to see how they recover. We need diversity and plant cover for fish. We also need a healthy level of native plants to help prevent EWM from returning.

?       A grant is not the only way to fund treatment of Sand Bar Lake, do we have to wait until the 2011? Yes we do need to wait until 2011.

?       If the native plants do not return on Tomahawk will you scrap the option of developing a plan for Sand Bar Lake? No

?       From experience in dealing with EWM on other lakes…how soon will you know if it has truly been eradicated or whether it will return? We do not know beyond 3-5 years what affects will be. There has never been a case where one treatment has totally eliminated the plant. We will need to consider what the long term plan will be as we move forward.

?       Have you ever had a treatment that was this successful this soon? Not to anyone’s knowledge.

A member of the audience thanked the presenters.

Ingemar asked the group to think positively about the plan going forward. Many people are interested in the project and have time and money invested in the project. The Town of Barnes has been very supportive of the project.

Meeting adjourned at 3:10 P.M.