LONG LAKE PROPERTY OWNERS

ASSOCIATION, INC.

EURASIAN MILFOIL MEETING

Saturday, October 29, there will be a meeting at 10:00 AM at the Plainfield Township Hall with EnviroScience Inc. and Fred Lewis, Township Supervisor, regarding the Long Lake milfoil problem and the weevil program.  You are invited to attend so that you can learn what the status of the program is, what steps will be taken next, and get the answers to any questions you might have.

This is a link to the 2011 Milfoil Solution Progress Report prepared by EnviroScience Inc.

2011 Long Lake Hale Report.pdf

Here is a link to an interesting news story about the progress resulting from the

application of weevils to combat Eurasian Milfoil in Puslinch Lake near Cambridge, Ontario.    

  http://www.youtube.com/watch?v=LJ52BZZvywI                                                                     

2010 Long Lake, Plainfield Township, MI

Milfoil Solution® Progress Report

Prepared for:

Introduction

Eurasian watermilfoil (Myriophyllum spicatum; here after EWM) is an exotic aquatic plant from Europe and Asia that is thought to have invaded the United States in 1930’s. This invasive species tolerates a wide range of growing conditions and out-competes native vegetation, which can lead to a monoculture of EWM. Thick beds of EWM limit recreational use, reduce biodiversity, and induce an unbalanced fishery. Furthermore, a severe EWM infestation can cause thermal stratification, and lead to a reduction in natural circulation causing dissolved oxygen and bacterial problems. It is due to these problems that managing EWM, once in an aquatic system, is important.

Table 1

Survey methods

Surveys are an important component of a Milfoil Solution® program, and provide lake managers, residents and EnviroScience staff information on how a program is progressing. Surveys are performed twice per season at each stocking and monitoring site to gather information on weevil and EWM populations. The initial survey is conducted just before weevils are stocked and is designed to provide information on pre-stocking conditions. The follow-up survey is performed later in the season to monitor changes in EWM and weevil populations during the season. During both surveys visual observations of the conditions at each site are recorded, which include: visual analysis of the EWM, presence of weevils and weevil-induced damage, and native plant species present. In addition to visual observations, samples are collected at each site to estimate both weevil density and EWM stem density. EWM stems are collected and brought back to the EnviroScience lab for analysis of number of weevils and presence of damage. In the field a EWM density square is randomly tossed and the number of stems within the square counted and later converted to estimate the number of EWM stems per square meter.

Results

2009 initial and follow-up surveys          

2010 initial and follow-up surveys

During three stocking events in 2010 (June 10th, 17th and 30th) six sites were surveyed and samples collected to estimate weevil and EWM densities. Field observations found larval damage present in all six sites. Based on the samples collected, weevil densities ranged from 0.00 to 0.32 weevils per stem (Table 1). EWM densities ranged from 137 – 188.89 stems/m2 (Table 2). The follow-up sampling on August 27th observed weevil damage in all six sites. Weevil densities ranged from 0.09 – 0.60 weevils per stem. Comparing the densities of the follow-up with the initial surveys show increases in four sites, a slight decrease in one. Due to a sampling error no data was collected from the monitoring site during the follow-up survey (Table 1). EWM densities increased in three sites and decreased in three sites throughout 2010 (Table 2). Combining these to estimate overall weevil population density at each site indicates that all sites had weevil population increases.

While conducting the follow-up survey in Long Lake several stocking sites were found to have been negatively impacted by weevil feeding. Sites S1, S2 and S3 had significant areas where EWM had sunk in the water column and were several feet below the surface. A high percentage of the sunken stems were hollowed out, a clear sign of weevil larval feeding. Sites S1 and S3 showed dramatic negative impact from when they were stocked in June. The affected areas in these beds corresponded to where the weevils had been stocked. All three of these beds still had areas were EWM was alive and forming surface mats but the negative impact of the weevils was clearly visible.

Discussion

The goal of the Milfoil Solution® program is to control the growth and spread of EWM using the milfoil weevil. When working with a biocontrol agent such as the weevil, it is important to remember that many factors contribute to its success and the rate at which the desired pest control is achieved. EWM control rates vary greatly between water bodies and seasons, and variables such as lake size, amount of EWM present in the lake, number of weevils stocked, and amount of recreation occurring on the lake all play a role in the weevils’ progress.

Overall, Long Lake appears to be on track to successfully controlling EWM using weevils. Each stocking site had an increase in the weevil population (#/m2) through 2010, and several sites have significant weevil damage present during the follow-up survey. The impacts of weevil stocking will be most evident in the sites where weevils are stocked and it is common for stocking sites to take more than one year before dramatic impacts are seen. Sites S1 and S3 in Long Lake are good examples of this. 2010 was the second year these sites were stocked, and both field observation and weevil density estimates show that these sites are progressing well. The most dramatic changes in 2011 will likely be seen in the sites that received their second year of stocking. These impacts may include reductions in overall bed area, EWM stem density, and/or area of surface matting.

Predicting how the sites established in 2010 in Long Lake will look the next year is difficult. Based on the data collected and observations of these sites I would predict that EWM in S2 will level off or decline and S4 and S5 may increase slightly. However, with continued weevil stocking these sites should follow the pattern of S1 and S2 and have EWM decrease after the second or third year of stocking.

Native plants are an important component in the long-term success of EWM control in a lake. As EWM decreases due to weevil feeding, native plants should return and begin competing for space and resources. While EWM remained the dominant plant in all stocking sites the percentage of native plants increased in the two of the three sites where EWM declined (S1 and S2). Native plants rarely reach the nuisance levels that EWM is capable of and are a key component in a healthy, thriving lake ecosystem.

Milfoil weevils are a natural process for controlling EWM and success is gradual. Weevil stocking in Long Lake has been concentrated in a few sites. This is an important strategy that maximizes natural weevil reproduction. This strategy often means EWM is still thriving and spreading in other areas of the lake, and this presents one of the most difficult challenges for people living on the lake to understand and accept. Our experience is that by concentrating stocking efforts and optimizing reproduction, weevil populations will produce enough offspring to naturally spread out to adjacent areas of EWM. Sites S3 and M1 are a good example of this. In 2009, while present in the monitoring site (M1), based on evidence of stem damage, the population was below detection levels. No weevils were stocked in M1 in either 2009 or 2010, yet a small population was detected in 2010 samples. This is likely due to weevils migrating from S3 both after overwintering on shore in 2009 and during the summers of 2009 and 2010. Given time and the appropriate level of stocking, milfoil weevils can provide long-term, lake-wide control of EWM.

 Weevil per stem density vs. population density

 Two estimates for weevil density are presented in this report and it is important to understand what they represent and why they are important. Milfoil Solution® sample collection methods enable us to easily estimate the number of weevils per EWM stem. This is an important number to track as it directly relates to the rate of damage weevils inflict on EWM (more weevils per stem = more damage to EWM). However, prior to weevil populations reaching the level of imparting control EWM growth can exceed weevil population growth. During this time using the number of weevils /stem estimates alone can falsely show a population decrease (S3 in 2010 is a good example of this). Incorporating the number of EWM stems available an area with the weevil stem densities provides a better gauge of weevil population at a site.

Future Recommendations

It is the recommendation of EnviroScience that the Plainfield Township continue to implement the Milfoil Solution® program at Long Lake. Evidence of weevil presence and signs of negative impacts on EWM is present in all sites. The results seen on Long Lake to date are in line with biological control of EWM using weevils. Multiple-year stocking of the milfoil weevil can increase the rate of EWM suppression and ensure long-term, sustainable control of EWM. As EWM in stocking sites is brought below the nuisance level additional stocking sites will be established.

Sincerely,

Tom Alwin

Aquatic Biologist

EURASIAN MILFOIL PROJECT

Middfoil® Project Description

Long Lake has been undergoing a rapid expansion of EWM in the past several years. This problem became significantly worse in 2009, due to a combination of factors including improved water clarity due to zebra mussels. Milfoil expanded tremendously during the summer of 2009, and nearly half of the broad shallow areas of the lake which support plant life are now dominated by milfoil. Because of this, EWM poses a considerable long-term threat to the recreational potential and ecological health of the lake.

Plainfield Township and the Long Lake Association had evaluated several alternatives for dealing with this problem, and in 2009 began a multi-year program involving stocking the Eurasian watermilfoil (EWM) weevil E. lecontei which is the active biological control agent in the MiddFoil® process. In addition to being an environmentally safe and cost-effective approach, milfoil weevils can provide long-term permanent control as opposed to chemical application which will need to be reapplied indefinitely.

 Recommendations for the stocking program begun in 2009 were based on site conditions observed during an August 2008 review of the lake. The significant expansion of the milfoil between the time of the 2008 review and the 2009 stocking of 22,000 weevils warrants re-evaluation of the original stocking program and the level of funding that supported it. 

Although every lake responds somewhat differently and there are few hard and fast guidelines for application, it is clear that the length of time needed for the weevils to achieve lake-wide control is proportional to the number that are stocked. Given the rapid expansion of the milfoil observed in 2009, we believe that the original stocking program will no longer provide the desired level of control in a reasonable period of time. For this reason, Plainfield Township has requested that EnviroScience provide recommendations and several different options for a revised treatment program. These options include a chemical-only approach, an integrated program involving spot herbicide application with weevil stocking, and a program involving stocking larger numbers of weevils.

Plainfield Township has received and reviewed proposals for the first two approaches and this proposal outlines the third, biological control-only, approach.  We believe that this stocking program will provide cost-effective control much faster than would have occurred under the previous program.

In addition to stocking weevils in each of the next three years, the project involves establishing baseline conditions and charting the progress of the project using detailed field surveys and laboratory analysis. This provides for the continuous monitoring of the MiddFoil® program and the evaluation of its progress. The data collected during the surveys helps to provide the necessary information for making future adjustments to the program. It also provides the client with an annual report detailing the status of the MiddFoil® program.

Three general tasks will be accomplished each year as part of the Long Lake MiddFoil® program.

Task 1: Initial survey, mapping of sites, and weevil stocking

An initial survey is conducted prior to each stocking event during the growing season (June – August).

Task 2: Follow-up Survey

A follow-up survey will be conducted at the end of the growing season (August - September).

Task 3: Reporting

Reports summarizing the progress of the MiddFoil program are generated at the end of each stocking year (September - December) and pursuant to the final follow-up survey.

 Yearly Summary of Expenses

                                                Number of                                                                                                                                  

Year       Survey Cost    ReportCost          Weevils     Weevil Cost    Total Cost

2010       $3,269.40        $750.00            95,000        $76,000.00     $80,019.40

2011       $3,215.90        $787.50            60,000        $48,000.00     $52,003.40

2012       $4,380.20        $909.48            40,000        $32,000.00     $37,289.68

2013       $2,049.54     $1,041.84             0                   0                $3,091.38

Total     $12,915.04    $3,488.82      195,000      $156,000.00

Sorry about the quality of this scanned document.  Hopefully, you will be able to read it.

March 13, 2010

 To:  Long Lake Property Owners

Subject:  Milfoil Management Program

             As all of you know, the Eurasian water milfoil in Long Lake has spread at a rampant rate during the summer and fall of 2009.  The present program of weevil plantings by Enviro Science will not provide the desired level of control in a reasonable period of time.  Therefore, we are looking at a revised proposal for 2010 thru 2013. 

             Mechanical harvesting is not an option because of the problem that when the milfoil is cut or torn it spreads even faster.  Chemical treatment has been successful in many lakes, but it is more expensive and must be continuously reapplied.  I, for one, do not want chemicals in Long Lake. 

            The new proposal is to continue with the weevils.  The stocking program for 2010 was originally for 12,000 weevils, the new proposal goes to 95,000, 2011 from 9,000 to 60,000, 2012 from 0 to 40,000 and 2013 would be zero based on of the outcome of 2010 thru 2012 program.

             The increased cost to each property owner would be approximately $390.00 over the next four years.  Fred Lewis, Plainfield TWP Supervisor, and Robert Cudney, Board of Commissioners for Iosco County are looking for ways to provide funding to help cover some of the cost.

             April 10, 2010 at 1:00 PM there will be an information meeting to be held at the Plainfield TWP Hall in Hale.  April 25, 2010 at 1:00 PM a public hearing will be held to increase the assessment.  I know that some of us will not be able to attend these meetings, but we need your help.  Please send an e-mail or letter to Fred Lewis telling him we must save Long Lake from the spread of Eurasian milfoil and you agree with the increased assessment.  Fred’s e-mail is:  supervisor@plainfieldtwpmi.com  the address is:  Plainfield Township, 220 N. Washington, Hale, MI  48739.

             Your approval of the revised program would be appreciated!!

                                                 James Ouillette, President

                                                Long Lake Property Owners Assn.