A Summary of Findings from a LakeScan™ Guided Survey and ...cms5.revize.com/revize/montcalm/Drain...

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A Summary of Findings from a LakeScan™ Guided Survey and Analysis of:

Tamarack Lake Montcalm County, MI

PART 2: DATA AND ANALYSIS EXECUTIVE SUMMARY

Submitted by:

Dr. G. Douglas Pullman Aquest Corporation

Tamarack Lake 2018 Category 700 Analysis

Executive Summary Report, Pt 2

PREFACE Lakes are complicated systems. There is no simple way to consider all of the interacting systems within a lake and the impact of watersheds and invasive species invasions on these valuable resources. LakeScan™ is a comprehensive system of analysis that is necessary to properly consider conditions in a lake and make reasonable, scientific and empirically based recommendations for management and improvement of aquatic ecosystems. Persons who are already familiar with the LakeScan™ method may wish to skip to Part 2 since the methods and approach sections are primarily “boilerplate”. This report is only the “tip of the iceberg”. All recommendations are based on the comprehensive record of data that are included in the Tamarack Lake, LakeScan™ annual review document. That report is available under separate cover.

TABLE OF CONTENTS

Section Page

PART 2. An Overview and Summary of Conditions, 2018 4

CAT 700: Aquatic Plant Community Status Summary 5

CAT 700: Selected LakeScan™ 2018 and Historical Data 6

CAT 700: Issues and Answers 11

CAT 750: Nuisance and Invasive Weeds and Management 12

CAT 750: Common Plants and Management Prescriptives 14



Tamarack Lake LakeScan™ AROS (Aquatic Resource Observation Site) map. Observation data is collected from each AROS. The colored areas represent distinct biological tiers where distinct biological communities are found.

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Tamarack Lake323 Acres

Montcalm CountyCato Township

T.12N, R..8E Sec 9, 10,43.4442ºN, 85.2661ºW

Williams LakeBiological Tiers

Tier 3 22 Acres

Tier 4 147 Acres

Tier 7 44 Acres



Category 700: LakeScan™ Analysis Highlights – the 2018 Plant Community. Background: The LakeScan™ method uses nine different measures of the plant community to determine the condition of this critical part of the lake ecosystem. These measures or metrics were applied to the whole lake and to individual or distinct areas including biological tiers, management zones, or treatment zones (where applicable). These data were also used to consider groupings of plant species that differ in quality, invasiveness, and impact on ecosystem stability. For example; plant community biodiversity is calculated “with weed species” and “without weed species”. These data were used to compare conditions that were surveyed at different times of the year – early and late summer. All of these data are can also be compared in year-to-year or lake-to-lake analysis. This analysis is used to formulate the most appropriate management plan for the plant community and to make certain that any management interventions result in no further degradation of the lake ecosystem. These data are also necessary to satisfy some of the regulatory conditions imposed by States and Federal agencies. A typical LakeScan™ report is over 100 pages, but is presented in an easy to understand, graphical format. Readers are encouraged to read the entire annual LakeScan™ report for this and other lakes. However, some readers are interested in a summary version of the report. This executive summary has been developed for those readers and provides a glimpse of the comprehensive the analysis that is used to evaluate the Tamarack Lake plant community and inform management decisions. LakeScan™ is a comprehensive lake analysis system that is able to consider all of the physical, chemical, and biological systems that contribute to lake condition. Category 700 is aimed at plant and weed communities and this kind of monitoring and analysis was begun in 2016 on Tamarack Lake. Tamarack Lake is currently one of nearly three dozen Michigan inland lakes where LakeScan™ is used to monitor aquatic plant community conditions (Category 700) and evaluate the results of the aquatic vegetation management program. LakeScan™ metric target values are determined and derived from observations and analysis made from a very wide range of lakes that differ in size, shape, shoreline development, and chemistry. Some of these lakes are virtually filled with plants because of basin morphometry and sediment fertility and structure. These lakes can support very high metric values and support a stabile ecosystem if they are properly managed. Other lakes support very little rooted plant and bottom dwelling vegetation and metric values tend to trend lower. Tamarack Lake is a highly plant productive compared to most other Michigan inland lakes. The plant community that is present in the lake is only moderately diverse and ecosystem stability is low. LakeScan™ plant community metric values narrowly expectations in 2018. Nuisance conditions and species dominance vary widely each year (every year is different) and this seems to be a function of the annual growth and production of ebrid watermilfoil. The dominant water milfoil was identified as a Eurasian x northern (Michigan native) hybrid in 2003 by Aquest Corp. and the University of Connecticut. These hybrids are referred to collectively as ebrid watermilfoil and it currently dominates the lake flora. The ebrid watermilfoil in Tamarack Lake is seemingly diseased or vigor compromised. It was virtually inconspicuous during the early summer of 2014 but did recover to a low level of percent occurrence and dominance by the late summer. It returned to “normal nuisance levels” by 2015. The ebrid watermilfoil in Tamarack Lake has become resistant to most common control agents including 2,4-D, triclopyr and diquat dibromide. The lack of vigor that is of unknown origin and the presence of a vibrant microbial community that appears to be capable of desensitizing the ebrid water milfoil to exposure to herbicides appears to be the primary mechanisms for this resistance The current management program appears to have possibly caused the ebrid watermilfoil in the primary permitted treatment areas to be more thin and patchy. But it is probably more likely that



the recurrent and common ebrid watermilfoil bloom and crash cycles in Tamarack Lake is more responsible for the decline of nuisance watermilfoil populations in the lake. Even though there have been no obvious symptoms of herbicide exposuore when treated plants are compared to untreated plants, the treatment area does not generally support the same level of milfoil production. Starry stonewort is another exotic plant invader from other continents. It was observed at typical percent occurrence and dominance levels in Tamarack Lake before 2015 but has not been conspicuously present in the lake since then. Tamarack Lake would seem to be a good lake for Starry Stonewort to become dominant, but the plant has not seemed to be able to take hold as it has in hundreds of other Michigan inland lakes. At this point it appears that starry stonewort will not be a major factor in Tamarack Lake. However, careful monitoring is necessary to make certain that appropriate action is taken if critical lake mechanisms and values are threatened and avoid unnecessary management. Year-to-year trends are calculated for LakeScan™ metric values. Metric values have varied only slightly in the past five years. However, vales have trended to the positive since monitoring was begun. It would seem reasonable to expect Tamarack to meet or exceed metric target values. Close monitoring is necessary to evaluate impacts of invasive species on ecosystem stability (lake health) and will help to make best management decisions. This will also help to make better predictions regarding the nuisance potentials of species found in the lake. The quality of plant species found in Tamarack Lake was very good in 2018 since more than 75% of the species present since 2014 have plant target (t values) values greater than 2 on a scale from 1 to 4. Species rarely become weedy when they are assigned T values from 2 to 4. Several desirable native Michigan pondweed species have increased dramatically in percent AROS cover and dominance and this is considered to be a very positive sign of improvement. The biodiversity in Tamarack Lake continues to be disappointing despite the increase in native aquatic plant cover and production. It is critical to protect the plant communities in all tiers from the influence of opportunistic invasive aquatic weeds. Perceived nuisance levels were high in Tamarack Lake in 2018 but were not as high as 2016. Ebrid watermilfoil was the dominant nuisance in 2018. It is abundantly clear that LakeScan™ metric values are likely to be heavily influenced by the presence or absence of invasive species and could decline rapidly if these species are not successfully suppressed by targeted and highly selective plant species management strategies and technologies.



A Graphic Review of Selected LakeScan™ Metrics Used to Evaluate Lake Conditions in Tamarack Lake

Table ESP2-1.0 Selected LakeScan™ metric values and target values, 2018. Metric target values are based on values collected from a wide range of Michigan inland lakes and may not be totally appropriate for lakes like Tamarack Lake. However, as the LakeScan™ database continues to grow, it may be possible to establish more realistic target values based on lake groupings. Pink backgrounds are used to highlight metric target values that have not been met or exceeded target values and highlight trends in annual data that are not positive. Blue backgrounds are used to highlight metric values that have exceeded expectations and highlight metric values that trend positively from year to year. Pink is “not good” and blue “is good”.

LakeScan™ Metrics and Targets

2018 Target TrendValues Values Analysis

Species Richness 13 16 +Morphotype 11 12 +

Mean Weighted C 5.5 5 +Whole Lake BioD 28 40 +

Whole Lake BioD T2+ 16 25 +MorphoD 83 70 +

Weediness 4.3 5.0 -Mean Perceived Nuisance 89 50 -



Table ESP2-2.1 Historical perspectives are provided for the current year and averaged over years since LakeScan™ monitoring began in 2016. Target values are selected subjectively and may change as the LakeScan™ database expands and different kinds of lakes can be grouped into meaningful assemblages. Metric values where the header is blue, and the footer is pink depict metrics where greater values are better. Lower values are better for the last two metrics, Weediness and PNL Index where the header is pink, and the footer is blue.

Table ESP2-2.2 Historical perspectives on selected LakeScan™ metric data collected during the previous years. Mean metric values represent a sum of all relevant data or a mean value derived from observations collected at several vegetation community surveys that were conducted throughout each summer/growing season. Metric values where the header is blue, and the footer is pink depict metrics where greater values are better. Lower values are better for the last two metrics, Weediness and PNL Index where the header is pink, and the footer is blue.

Historical AveragesTotal Years = 13

Species Morpho- Weighted Whole Lake Lake Biovol MeanRichness types Mean C BioD BioD T2+ MorphoD ft3/acre ft Weediness PNL

Tamarack Lake 2018 13 11 5.5 28 16 83 407 4.3 87Target Values 16 12 5.0 40 25 70 407 5.0 50

Historical Average 12 9 4.1 22 14 60 242 4.5 77Historical Metric Range 5 to 14 4 to 11 2.1 to 5.5 6 to 30 5 to 21 12 to 83 134 to 407 3.6 to 5.5 51 to 93

Annual Data Comparisons

Species Morpho- Whole Lake Lake Biovol MeanRichness types Mean C BioD BioD T2+ MorphoD ft3/acre ft Weediness PNL

2014 13 11 4.2 25 14 74 185 4.32015 13 10 4.6 27 16 69 134 3.62016 14 11 4.9 30 17 79 303 4.3 932017 14 11 4.7 30 21 78 270 3.9 512018 13 11 5.5 28 16 83 407 4.3 87

Two distinct ebrid watermilfoil plants in Tamarack Lake, 2018



Figure ESP2-1.1 Species richness is the total number of species that are present during a LakeScan™ survey. Each of the species are assigned different target values, T-1, T-2, T-3, T-4. These target values are related to the probability that that species would be targeted for control or management in the lake. T-1 species are usually very weedy and create the greatest nuisance conditions and are therefore most likely to be targeted for control by a variety of means. T-2 species are occasional nuisance species and may be targeted for control in some circumstances. T-3 species are not targeted for control but may sustain some collateral damage if near other species that are targeted for control of suppression. T-4 species are protected from impact from any management activity.

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Table ESP2-2.3 A listing of submersed aquatic plants found in Tamarack Lake in 2018. Color highlights are used to signify the management target values normally assigned to different aquatic plant species. Species highlighted in red are common weed species and are commonly targeted for control as “T1” species. T2 species are sometimes targeted for suppression depending upon the situation and the observed aggressiveness of the species present in an individual lake. T3 species are rarely targeted for management because they are generally not weedy.

Table ESP2-2.3 A listing of submersed aquatic plants found in Tamarack Lake in 2018. Species are ranked according to species occurrence at each AROS, LakeScan™ species dominance factor, relative biovolume, and perceived nuisance value.

CODE REFERENCETOTAL

PHENO- T i c MORPHLEAF AND STRUCTURAL MORPHOTYPE

# NAME TYPES COMMON NAME SCIENTIFIC NAME VALUE VALUE VALUE # DESCRIPTION

1 2 EWMx 0 Eurasian Watermilfoil Hybrid Myriophyllum spicatum x sibiricum 1 8 3 3 feathery

2 33 CNTL 0 Coontail Ceratophyllum sp. 2 7 3 3 bushy

3 42 ELD 0 Elodea Elodea sp. 2 6 3 3 bushy

4 50 NAID 0 Naiad Najas sp. 2 7 4 4 bushy

5 60 CHARA 0 Chara Chara sp. 4 3 6 6 bushy

6 65 StSt 0 Starry Stonewort Nitellopsis obtusa (Desv.) J.Groves 1 9 3 3 bushy

7 75 CLP 0 Curly Leaf Pondweed Potamogeton crispus L. 1 9 2 2 narrow leafy

8 109 HPW 0 Hybrid Pondweed Potamogeton Hybrid 2 5 5 5 broad leafy

9 110 WBLP 0 Weedy Broad Leaf Pondweed Potamogeton amplifolius Hybrid 2 6 4 4 broad leafy

10 115 Stuk 0 Sago Pondweed Stuckenia sp. 2 6 3 3 stringy

11 125 VAL 0 Wild Celery Vallisneria americana Michaux 2 7 3 3 grassy

12 150 WL 0 Waterlily Nymphaea sp. 2 5 6 6 floating leaf

13 155 WSh 0 Water Shield Brasenia schreberi J.F. Gmel. 3 5 7 7 floating leaf

2018 PLANT NAME, CODES, AND SELECTED ATTRIBUTES

REFERENCEPRESENT IN 2018

TOTAL YEARS

PRESENT IN LAKE

NAME COMMON NAME √ # SPECIES PERCENT SPECIES VALUE SPECIES VALUE SPECIES VALUE

1 EWMx Eurasian Watermilfoil Hybrid √ 13 CHARA 99% CHARA 54 CHARA 51 EWMx 114

2 CNTL Coontail √ 13 EWMx 94% EWMx 41 NAID 33 CLP 60

3 ELD Elodea √ 13 CLP 69% CLP 31 CLP 25 HPW 7

4 NAID Naiad √ 10 ELD 61% ELD 30 ELD 25 CHARA 6

5 CHARA Chara √ 12 HPW 49% WL 28 EWMx 23 WL 6

6 StSt Starry Stonewort √ 4 WL 46% HPW 28 CNTL 19 VAL 2

7 CLP Curly Leaf Pondweed √ 12 NAID 37% NAID 24 HPW 19 NAID 2

8 HPW Hybrid Pondweed √ 9 WBLP 31% WBLP 21 WBLP 17

9 WBLP Weedy Broad Leaf Pondweed √ 11 Stuk 29% CNTL 18 VAL 15

10 Stuk Sago Pondweed √ 9 CNTL 24% Stuk 16 StSt 12

11 VAL Wild Celery √ 6 VAL 14% VAL 14 Stuk 8

12 WL Waterlily √ 8 WSh 10% WSh 10 WL 6

13 WSh Water Shield √ 1 StSt 3% StSt 8 WSh 5

SPECIES OCCURRENCE RANKING

SPECIES DOMINANCE RANKING

RELATIVE BIOVOLUME RANKING

SPECIES PERCEIVED NUISANCE LEVEL

FACTOR RANKING

2018 PLANT SPECIES SELECTED METRICS AND BY RANK



ANTICIPATED ISSUES ANSWERS

OVERALL LAKE CONDITION The Tamarack Lake ecosystem is inherently unstable. Most LakeScan™ metric values are considered to be good for Tamarack lake even though they did not reach target values in 2018. Conditions have steadily improved during the past four years of LakeScan™ monitoring. However, invasive species continue to be a threat to the lake and extreme herbicide resistance is greatly complicating the ability to achieve stated management goals.

Invasive species will continue to threaten the plant community diversity, critical habitat values, ecosystem stability, and recreational value of the lake. Targeted management is required to protect the lake and prevent deterioration of conditions and these efforts have yielded excellent outcomes. However, the ebrid watermilfoil in this system has become extremely herbicide resistant while also being unusually inclined to decline. Monitoring is required to provide evidence that management interventions are necessary to protect the lake from individual species threats. Treatment outcomes since 2010 have been equivocal because of the frequent, whole-lake decline of ebrid watermilfoil.

Ebrid watermilfoil has exhibited signs of disease or other compromising factors for nearly a decade. It has varied considerably in percent AROS cover, dominance and nuisance level since 2010. The entire ebrid milfoil communilty has also been observed to collapse randomly. Herbicide applications have been performed, but definitive signs of impact have not been observed because all of the milfoil has declined in treated and untreated areas soon after treatment. Various herbicides and herbicide combinations have been used but have not produced different results. The treatments performed in 2018 did not produce perceivable results.

Careful monitoring is required to determine the relative dominance of ebrid milfoil. Ebrid milfoil did not respond to treatment in an observable manner in 2018. It did collapse after the Fourth of July holiday, but this cannot be attributed to the herbicide application. A later herbicide application did not produce obvious results sine ebrid watermilfoil appeared to be similar in both treated and untreated zones. The monitoring schedule needs to be increased to determine the best management practices for the ebrid watermilfoil in this lake.

Starry stonewort is an alga that looks like a higher plant. It is more aggressive than any other aquatic plant in Michigan and can outcompete all the species currently found in Tamarack Lake. However, it has not been observed to grow to typical nuisance levels and has not created a conspicuous presence during the last several years. It is very possible that starry stonewort will not grow to the nuisance levels observed in other lakes.

Careful monitoring and management are required to prevent the loss of plant community biodiversity and degradation of recreation values in lakes that have become infested with starry stonewort. It did not require any specific management action in Tamarack Lake in 2018. However, this plant is so predictably unpredictable that it could create a serious nuisance condition in the future. The rapid growth of this plant cannot be understated, and careful monitoring is necessary.

Native plants and pondweed production was considered to have reached nuisance levels in some parts of Tamarack Lake. Nuisance growth was patchy and may have provided some ecosystem benefits, but the high level of dominance of these species is still a major concern. Elodea production has been unusually high in Tamarack Lake but did not reache the levels that have been observed in previous years.

Careful monitoring of native plant production is required to determine if native plants could create a wide-spread and significant nuisance. Should this occur, management action may be necessary. Elodea production needs to be closely monitored and ameliorative action taken should it reach nuisance levels.



Category 750: LakeScan™ Management Program, 2018

Perceived Nuisance Index, “PNL” Index and Invasive or Nuisance Species.

Background: There are several species that typically become a nuisance in Michigan’s inland lakes. These species are usually targeted for very selective control to prevent them from becoming an aesthetic or recreational nuisance and to protect desirable plants that are part of lake floras. The species that are nearly always targeted for control are referred to as T1 species in LakeScan™ parlance.

Tamarack Lake 2018: Only thirteen different plant species were observed in Tamarack Lake in 2018. Nuisance aquatic plant conditions were observed in 80% of all lake observation sites (AROS). Ebrid milfoil is expected to be the dominant nuisance in 2019 and would seem to be the greatest threat to the lake. However, various native Michigan pondweeds were significantly present in 2018 and could potentially grow to nuiance levels in the future. Prudent management of all native plant growth is important because the production of some of these plant genotypes are necessary to stabilize the ecosystem. However, nuisance conditions created by some genotypes must be suppressed if they threaten the stability of the ecosystem and diversity of the plant community.

Table ESP2-3.1 The perceived nuisance level (PNL) is determined at each AROS during the LakeScan™ surveys. The AROS acre is the area of each lake Tier (see Tier Map above) divided by the number of AROS that lie inside that tier. The maximum PNL values that are found at each AROS during the seasonal LakeScan™ surveys is used for this analysis. The total number of AROS acres is summed for each of the four PNL levels and the “no nuisance” AROS (PNL 0). The first column is the percentage of the total AROS acres of AROS that are assigned each PNL value.

60.6 3.0 58.1 181.2

0% 25% 50% 75% 100%

Total Nuisance and No Nuisance AROS Acres

No Nuisance PNL 1 PNL 2 PNL 3



Tamarack Lake Management Zones (MZL):

MZL’s are areas where different management objectives are used that are consistent with the over-all program goal. These objectives range from highly species selective management intervention strategies and technologies (MIST) to fairly broad-spectrum controls that might be considered desirable in a swimming area or marinas. The selection and designation of the areas is based on the ecological significance of the area and State regulatory policy. MZL 4 areas are the most aggressively managed areas in lakes where strategies are non-selective and may be applied frequently throughout the growing season. Again, these areas include swimming areas and marinas. MZL 3 areas are also aggressively managed but the focus is generally to prevent the weediest species from growing at nuisance levels near homes and commercial developments. Lake access is the critical focus in MZL 3 areas and selectivity is a subordinate priority. Only T1 (Target 1) species, such as milfoil, curly leaf pondweed, and starry stonewort are targeted in MZL 2 areas, but there may be some temporary impacts on desirable plants. Only the most highly selective management agents are applied to MZL 1 and the objectives in these areas are to focus on only a single species or two.

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Tamarack Lake323 Acres

Montcalm CountyCato Township

T.12N, R..8E Sec 9, 10,43.4442ºN, 85.2661ºW

Tamarack LakeManagement Zone Areasx

MZL 3 51 Acres

MAL 2 214 Acres



Management Interventions Strategies and Technologies (MIST)

Ebrid watermilfoil growth may reach nuisance levels around the Memorial Day Holiday in Tamarack Lake. The lake is surveyed in May or early June (depending on weather) and specific targets are established during that survey. Species selective herbicide combinations are applied to the lake to target invasive species and encourage the development of a biologically diverse, desirable, native plant community. Mechanical management strategies are sometimes used to manage herbicide resistant nuisance native pondweeds or areas where flow is too great for the use of selective herbicide application technologies. However, mechanical harvesting is currently not a part of the Tamarack Lake management program. Different areas of the lake are treated with herbicides and herbicide combinations each year and the total number of acres will typically vary according to conditions. Small areas do not respond well to chemical or mechanical treatment, so larger areas are targeted for control to enhance the efficacy of treatments and preclude the “trap” of numerous, recurring treatments.

Comments on Individual Species Production and Management

Eurasian Watermilfoil and Hybrids (Ebrids):

Background: Anecdotal evidence suggests that hybrid milfoil has been found in Michigan inland lakes for a long time (since the late 1980’s). University of Connecticut professor Dr. Don Les was the first to determine that there were indeed, Eurasian watermilfoil and northern watermilfoil hybrids in Michigan based on samples sent to his Connecticut lab by Dr. Douglas Pullman, Aquest Corp. in 2003. Experience has proven that it is usually not possible to determine the milfoil observed is either Eurasian or hybrid genotype. However, because they play such similar roles in lake ecology, they are simply “lumped together” and referred to collectively as ebrid milfoil. Ebrid milfoil is a very common nuisance in many Michigan inland lakes.

Tamarack Lake 2018: Once again, ebrid milfoil percent occurrence and dominance was considered to have been the primary impairment for lake use and ecosystem stability during much of the summer of 2018. MDEQ permits seriously constrained the use of necessary antimicrobial agents that are required to obtain optimum results from ebrid watermilfoil targeted herbicide treatments. However, this constraints may encumber the ebrid watermilfoil management program in the future.

Early season ebrid watermilfoil appeared to lack the vigor that is associated with successfully herbicide treatment. The first treatment was done during the first week of June when it was hoped that the milfoil would resume active or more vigorous growth, but it did not seem to produce an acceptable outcome. According to reports from residents, nuisance conditions persisted until after the Fourth of July Holiday. Fortunately, the ebrid watermilfoil community seemed to collapse after the (reported by residents). However, there was resurgent growth of



the ebrid watermilfoil community in August and a second treatment was performed on August 14. A survey was conducted on September 26 and there were no obvious signs that there was any difference between treated and untreated area in the lake. Fortunately, most of the ebrid watermilfoil in the lake appeared to be health compromised and seemed to drop from the water column soon after the survey. Conditions for recreation were reported to be excellent after this community collapse.

It is interesting to note that two distinctly different ebrid milfoil types were observed in the lake on 26 September. One of these genotypes appeared to be emerging from fragment or seed and was growing vigorously when compared to the other common genotype. Samples were sent to Dr. Ryan Thum at Montana State University for genetic analysis. The health compromised milfoil did not seem to grow well in their mesocosms (diseased plants?) and it is unclear if definitive results will be obtained.

Continued monitoring is necessary to learn more about the existing genotypes in Tamarack Lake. It appears that treatment timing and the selection of primary control agents are not the most significant factors in determining the success of ebrid watermilfoil treatments. Rather, the presence of vigorous growth and status of biofilms, aufwuchs communities, and sediment microbiology seem to be the principle determinants of treatment success.

.

Figure 704. Ebrid milfoil (Eurasian water milfoil + Eurasian and northern watermilfoil hybrids = Ebrid) Perceived Nuisance Levels. These include recreational and aesthetic nuisances, ecological nuisances, and non-nuisance rankings assigned to each AROS and the sum of acres for each PNL designation for data collected throughout the entire summer. Nuisance acres are represented by pinks and reds. PNL-2 = “Equivocal Recreational Nuisance” is pink and PNL-3 = “Unequivocal Nuisance” (everyone would agree that conditions are bad) is represented by the red bars. PNL 1 = “Ecological Nuisance Only” are represented in blue. The green bars represent AROS acres where ebrid milfoil was not detected.

Figure 705. Ebrid milfoil (Eurasian water milfoil + Eurasian and northern watermilfoil hybrids = Ebrid) dominance recorded in the AROS of Tamarack Lake. AROS are assigned to all of the plant productive and potentially plant productive parts of the lake.

9 84 3 53 154

0% 25% 50% 75% 100%

Percent Total AROS Acres

Total AROS and EWMx AROS AcresNot Observed No Nuisance PNL 1 PNL 2 PNL 3

22 1242 45 45 35 37 44 42

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Inde

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EWMx Dominance in Lake

2014 2015 2016 2017 2018



Ebrid watermilfoil from an area that was treated with aquatic herbicides in August 2018

Ebrid watermilfoil from an area that was NOT treated with aquatic herbicides in August 2018

Figure 706. Treated and untreated ebrid milfoil (Eurasian water milfoil + Eurasian and northern watermilfoil hybrids = Ebrid) in Tamarack Lake as photographed on August 26th following an August 14th treatment with several herbicides. These photos illustrate the minor differences that were observed after treatment and were taken just prior to the decline of a ebrid watermilfoil genotype in other parts of the lake. Note: another ebrid watermilfoil genotype was also observed in the lake and this genotype did not appear to be compromised in any way.



Prescriptives: Ebrid milfoil can grow to significant nuisance levels throughout much of Tamarack Lake and is an ever-present threat to recreation, property values and the biological diversity and ecological stability of the lake ecosystem. Herbicide treatment outcomes have been questionable since 2010 since there have been few observed differences between treated and untreated plants. Furthermore, treatment evaluations have been confounded by recurrent events where the ebrid watermilfoil community, throughout the entire lake, will collapse concurrently with a herbicide application. The herbicide treatment in early 2018 did not deliver acceptable results. And, even though milfoil densities were lower in typical treatment areas, there was little evidence that the treatments provided acceptable outcomes. Ebrid watermilfoil blooms and declines have been observed at random time in this lake. Frequent monitoring will be required to determine the best timing, combination of agents, dose rates to achieve an acceptable level of ebrid watermilfoil control. Monthly lake evaluationls are strongly recommended. Milfoil community genetics are dynamic – not static, and careful monitoring is needed to adapt to the expected changes in the dominance of distinct milfoil genotypes. A distinctly different type of ebrid watermilfoil has emerged near the islands. It is not known if this particular genotype will be as weedy as the former genotypes. Nor is it known how this genotype will respond to management. It is hoped that the result of genetic testing being performed by Montana State University will shed some light on this issue.

Aquest has initiated discussions with the MDEQ regarding the use of anti-microbials to reduce the impact of enzymatic inhibition of herbicide impacts. Furthermore, these discussion include the use of an agent that may stimulate ebrid watermilfoil growth and make it more susceptiblel to the uptake of aquatic herbicides.

Pondweeds

Background: The pondweeds are possibly the most common plant found in Michigan inland lakes. They are a very large and diverse group of aquatic plants. All but one of the common Michigan Pondweeds are native or endemic. Curly leaf pondweed is the only exception and is native to Europe and Asia and is thought to have arrived in North America near the turn of the 20th century. It can become an extreme nuisance in the early spring but generally declines on its own prior to the important Fourth of July holiday. It seems to have been a more common nuisance in previous decades and has been less aggressive in recent years. However, it can still bloom near Memorial Day and become a terrible nuisance in some lakes – in some years.

The leaves of the native pondweeds range from thin stringy to broad and almost “cabbage-like”. This kind of morphological diversity contributes to the structural diversity of the submersed flora of lakes they inhabit and is believed to be an important component of constitutes critical habitat. More often than not, pondweeds are thought to be desirable because of the support they provide for a wide range of aquatic animals, including fish. Many of the most common species are considered to be promiscuous and hybrids, resulting from a variety of species crosses, abound in Michigan inland lakes. Although the native pondweeds are generally considered to



be desirable and rarely grow to nuisance levels, they have been observed to grow to increasingly nuisance levels during the past decade. American pondweed can grow to extreme nuisance levels in slow moving water. Sago pondweed has been observed at extreme nuisance levels in lakes where there has been excessive weed control pressure. There is a broad leaf pondweed/hybrid that forms a dense cover on the sediment in the late fall that over-winters and provides a strong competitive advantage to this biotype in the spring. The first reports that Richardson’s pondweed could grow to nuisance levels came from western Michigan more than ten years ago; however, it has been observed to grow to nuisance level throughout Michigan in the past 5 years. And finally, hybrids of Illinois, variable, white-stem, and broad leaf pondweed are becoming an increasing nuisance. There is no definitive answer or reason why the native pondweeds are emerging as increasingly weedy and problematic plants in inland lakes. However, it is not difficult to imagine that the pondweeds have evolved to become more aggressive after 40 years of competition with aggressive ebrid milfoils, curly leaf pondweed, and starry stonewort - and steadily increasing cultural disturbance in Michigan. Today, pondweed production must be carefully monitored. Management action may be required when particular pondweed biotype becomes invasive and threatens the diversity of large plant communities.



Tamarack Lake, 2018. Collectively, the pondweeds becoming more dominant in Tamarack Lake and will help to stabilize the ecosystem and provide native, critical habitat for the fishery. There are certain pondweed hybrids that can grow to nuisance levels so these shall be monitored closely in the lake.

Prescriptives: It is recommended that the production of various pondweeds be closely monitored before any specific management intervention strategy or technology (MIST) be considered for management. Curly leaf pondweed production has become highly unpredictable in Michigan, but it is very easy to manage selectively, with contact herbicides, should it present a substantial nuisance in 2019. The other pondweeds are much more resistant to herbicides than other plant species. Mechanical harvesting is generally recommended for nuisance pondweed management, despite the lack of selectivity. These matters shall be considered during the routine pre-season field review of conditions on Tamarack Lake.

American Pondweed

Hybrid Weedy Pondweed Pondweed

Sago Pondweed

Water Stargrass

Curly Leaf Pondweed

American Pondweed



Estimated Management Cost, 2019

Nuisance plant conditions have become increasingly unpredictable in Michigan inland lakes during the past decade. The emergence of unique genotypes and hybrids, that were not previously a part of inland lake floras, have injected a tremendous amount of variability into the management objectives that are applied each year. A spring survey is conducted with representatives of the Tamarack Lake lake management special assessment district, the lake management guidance advisor (Aquest), and any contractors that may be required to implement any of the prescribed objectives that are developed during this survey. The following budget is offered as an “extreme” worse case budget. Typically, far less action is necessary to protect the lake.

Projected Lake Management Cost Estimates, 2019

Task Description Total Events Unit Cost Total Cost

Cost of Services

Management Intervention Services

Ebrid Milfoil Management (Contacts) 2 Events (36 total acres) $10,620

Hybrid Milfoil (Systemics) 1 Event (5 acres) $3,225



Starry Stonewort Management Multiple (10 acres) $1,850

$15,695

Monitoring and Management Guidance

LakeScan™ Analysis (Vegetation) and Preseriptives 2 LakeScan Surveys $5,500 $5,500

Communications

TOTAL $21,195

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