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Iron River Pike Chain of 2017 AIS Monitoring & Lakes Association Control Strategy Assessment Report

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1.0 INTRODUCTION

The Pike Chain of Lakes is comprised of seven lake basins located near the Town of Iron River in Bayfield County, Wisconsin (Figure 1.0-1). The chain includes over 900 acres of surface water, and forms the headwaters of a drainage system that leads to the White River which flows through the Bad River Indian Reservation on its way to Lake Superior. All lakes within the chain are considered Areas of Special Natural Resource Interest (ASNRI) as outstanding or exceptional resource waters per Section 281.15 of Wisconsin Statutes. First documented in 2004 within the Twin Bear-Hart Lake channel, Eurasian water milfoil (EWM) has since spread to all seven of the Pike Chain of Lakes. The Iron River Pike Chain of Lakes Association (IRPCLA) and partners have engaged in an aggressive battle against EWM during this period, through direct control with spatially targeted herbicide spot treatments and hand-removal. Although annual (seasonal) success may have been gained, the herbicide treatment strategy has not been effective at keeping the EWM population from increasing within the chain. McCarry Lake is an approximately 31 acre drainage lake that flows into Hart Lake through a shallow channel (Figure 1.0-1). McCarry Lake was not originally within the project boundaries and was not professionally surveyed prior to 2017. Following the discovery of suspected EWM in the lake by IRPCLA members in 2016, McCarry Lake was included within the EWM monitoring studies in 2017. 1.1 EWM Population Trends

During the 2016 EWM Peak-biomass survey, each lake in the chain was surveyed to assess the EWM population at its peak growth stage. The results of the late-summer survey showed that the EWM population had expanded significantly in many areas of the chain since 2015 with an increase in EWM colonies mapped with polygons from 7.5 acres in 2015 to 45.6 acres in 2016 (Figure 1.1-1). Of the 45.6 acres of colonized EWM mapped in the Pike Chain in 2016, approximately 21.7 acres was comprised of colonies of dominant or greater density ratings, while an additional 23.9 acres were comprised of highly scattered or scattered density colonies. Point-intercept surveys were completed on each lake in the chain during 2016. These surveys serve as a quantitative assessment of the aquatic plant communities in each lake. The littoral frequency of occurrence (LFOO) of EWM from the 2016 point-intercept surveys in each lake is displayed on Figure 1.1-2. Lake Millicent (13.7%) and Hart Lake (10%) had the highest LFOO

Figure 1.0-1 Pike Chain of Lakes, Bayfield County, WI.


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of EWM in the chain during 2016. Twin Bear (7.0%) and Buskey Bay (6.3%) had a significant LFOO of EWM during 2016 compared to lesser amounts in Eagle Lake (1.0%) and Flynn Lake (0.9%).

1.2 Background on Large-Scale Herbicide Application Strategies

From an ecological perspective, large-scale treatments are those where the herbicide may be applied to specific sites, but when the herbicide dissipates from where it was applied and reaches equilibrium within the entire mixing volume of water (of the lake, lake basin, or within the epilimnion of the lake or lake basin); it is at a concentration that is sufficient to cause mortality to the target plant within that entire treated volume (Nault et al. 2012). A recent article by Nault et al. 2018 investigated 28 large-scale herbicide treatments in Wisconsin and found that “herbicide dissipation from the treatment sites into surrounding untreated waters was rapid (within 1 day) and lakewide low-concentration equilibriums were reached within the first few days after application.” WDNR administrative code defines large-scale treatments as those that exceed 10% of the littoral zone (NR 107.04[3]). As spot treatments approach 10% of a lake’s area, they are more likely to have large-scale impacts, which is why the WDNR has this check mechanism within the permitting process. Predicting success and native plant impacts from large-scale treatments is also better understood than for spot treatments. However, with any large-scale chemical treatment, both the positive and negative effects of this type of treatment strategy are anticipated to occur at a lakewide scale, whereas the impacts from spot treatments are mostly contained within and around the application sites.

Figure 1.1-1. Pike Chain of Lakes late season Eurasian water milfoil colony acreage, 2007-2016.

Figure 1.1-2. Littoral Frequency of Occurrence of EWM in the Pike Chain. Created from Onterra 2016 whole-lake aquatic plant point-intercept surveys.

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Figure 2.1-1 includes the entirety of Onterra-monitored 2,4-D large-scale treatments in the Northern Lakes and Forests Ecoregion that have progressed to at least 1 year after treatment (YAT). Also included on this figure are two lakes that received large-scale 2,4-D treatments that were monitored by WDNR as part of the EWM Long-Term Trends project discussed above. Properly implemented large-scale herbicide treatments can be highly effective, with minimal EWM, often zero, being detected for a year or two following the treatment (Figure 2.1-1). Some large-scale treatments have been effective at reducing EWM populations for 5 or more years following the application, whereas others have rebounded sooner (i.e. South Twin ’16, Sandbar ‘11).

Figure 1.2-1. Littoral frequency of occurrence of EWM in lakes managed with large-scale 2,4-D treatments. South Twin ’10 had treatment at 6 YAT, Kathan ’10 had treatment at 6 YAT, Sandbar ’11 had treatment at 2 YAT, Silver ’07 had treatment at 9 YAT. All others are ongoing. Lake manager’s ability to predict whole-lake herbicide concentrations has improved, but understanding the degradation period has not. In some cases, the biological breakdown of 2,4-D through microbial activity has been slower than typically observed. Nault et al. 2018 indicated the 2,4-D half-life was shown to range from 4-76 days within the 28 lakes studies, with the “rate of herbicide degradation to be slower in lower-nutrient seepage lakes.” Adding 9 additional Onterra-monitored projects to this dataset yields a mean 2,4-D half-life of approximately 30 days (Heath et al. 2018). Some native plants are resilient to large-scale 2,4-D treatments, either because they are inherently tolerant of the herbicide’s mode of action or they emerge later in the year than when the herbicide is active in the lake. Other species, particularly dicots, some thin-leaved pondweeds, and naiad species, can be impacted and take a number of years to recover (Nault et al. 2018). Often during the year of treatment, overall native plant biomass can be lessened but

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typically (not always) rebounds the following year. However, the preceding statements are a bit of a generalization because some case studies have had varying levels of EWM control even at high concentration and exposure times and others case studies had collateral native plant impacts greater than would be assumed considering the concentrations and exposure times achieved. 1.3 2017 Control and Monitoring Strategy

With Onterra’s assistance and input from the WDNR, the IRPCLA developed a multi-year EWM control and monitoring strategy for the Pike Chain of Lakes. Following discussions between project partners, the final EWM control program for 2017 included whole-lake herbicide treatments on four lakes in the Chain (Lake Millicent, Buskey Bay, Hart Lake, and Twin Bear Lake) as well as professional hand-harvesting in Eagle Lake. A cyclic series of steps were used to plan and monitor the large-scale 2,4-D control efforts. The series includes conducting the following surveys during the year before treatment, year of treatment, and year after treatment. Table 1.3-1 outlines the timeline for the 3-year grant-funded project. However, additional surveys would occur in 2019 and beyond to continue the monitoring strategy and would likely be covered by subsequent grants.

A lake-wide mapping assessment of EWM completed while the plant is at peak growth stage (peak biomass).

An acoustic survey of the lake to provide updated bathymetric information for proper herbicide dosing.

Quantitative assessments of the native and non-native aquatic plant community of the lake utilizing point-intercept survey methodology.

Table 1.3-1. Control and Monitoring Strategy Timeline

The objective of an herbicide treatment strategy is to maximize target species (EWM) mortality while minimizing impacts to valuable native aquatic plant species. Monitoring herbicide treatments and defining their success incorporates both quantitative and qualitative methods. As the name suggests, quantitative monitoring involves comparing number data (or quantities) such as plant frequency of occurrence before and after the control strategy is implemented. Qualitative monitoring is completed by comparing visual data such as AIS colony density ratings before and after the treatments.

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Because the 2017 treatments were anticipated to have whole-lake effects, the whole-lake point-intercept method as described by the WDNR Bureau of Science Services (PUB-SS-1068 2010) was used to complete a quantitative evaluation of the occurrences of non-native and native aquatic plant species. To monitor the treatment’s efficacy, a whole-lake point-intercept survey was conducted in 2016 (year prior to treatment), 2017 (year of treatment), and planned for 2018 (year following treatment). The quantitative success criteria of a whole-lake treatment would be a 70% reduction in EWM littoral frequency of occurrence comparing point-intercept surveys from the year prior to the treatment (2016) to the year after the treatment (2018). Understanding the EWM population in 2017 (year of treatment) is important, but an insufficient time has passed to make official judgements if EWM control occurred or if the plants were simply injured for that season and can quickly rebound. Qualitative monitoring will be conducted annually through EWM mapping surveys on the project lakes using either 1) point-based or 2) area-based methodologies. Large colonies >40 feet in diameter are mapped using polygons (areas) and were qualitatively attributed a density rating based upon a five-tiered scale from highly scattered to surface matting. Point-based techniques are applied to locations that were considered as small plant colonies (<40 feet in diameter), clumps of plants, or single or few plants. In-lake herbicide concentrations were monitored following implementation of the large-scale treatments to determine if the target concentrations and exposure length had been met. This activity was completed by IRPCLA volunteers with direction and equipment provided by Onterra. The 2017 plan included water samples being collected at 14 sites (Map 1) at specific time intervals using an integrated sampler (near-surface samples) or Van Dorn sampler (near-bottom samples). The water samples were fixed (preserved) with acid, stored in a refrigerator, and eventually shipped to the Wisconsin State Lab of Hygiene (SLOH) where the herbicide analysis was completed. As a part of an integrated control strategy approach for 2017, professional hand-harvesting of EWM was proposed to occur in select locations of the Pike Chain. Professional hand-harvesting efforts were determined to be the most beneficial in areas of Eagle or Flynn Lake where large-scale herbicide control activities were not proposed to occur in 2017. An early summer EWM mapping survey of Eagle Lake and Flynn Lake was used to develop the final hand-harvesting strategy for 2017. 1.4 Pre-Treatment Survey and Final Dosing

The success of properly planning and implementing a large-scale treatment strategy relies upon accurate bathymetric information with which advanced water volume calculations are conducted. This ensures that the dosing strategy is appropriate to impact the target plant and to minimize collateral effects on the native plant community. Volume calculations utilized the data obtained from the fall 2016 acoustic data for determining the target herbicide application dosages for each lake.


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On May 23-24, 2017, Onterra ecologists conducted the EWM Spring Pre-treatment Confirmation and Refinement Survey on the Pike Chain of Lakes. During this survey, the presence of actively growing EWM was confirmed within the proposed treatment sites. Modest native aquatic plant growth was observed and native species included fern-leaf pondweed and large-leaf pondweed. Temperature profiles were recorded at the deep hole monitoring sites in the four lakes proposed for treatment. Onterra staff provided training and delivered the herbicide monitoring supplies to IRPCLA volunteers that would be completing the water sampling for the treatment monitoring program. All herbicide concentration monitoring locations were loaded onto the IRPLCA’s Garmin GPS system during the survey. No alterations were made to the treatment area extents following the pre-treatment survey. In order to finalize the dosing volume for the 2017 treatment, it was necessary to understand the volume of water in which the herbicide is expected to mix. As the water warms, a thermal barrier develops in many lakes essentially separating the lake into an upper epilimnion with warmer water temperatures and a lower hypolimnion with cooler water temperatures. The transitional area separating the upper and lower portions of the water column or metalimnion, is used to calculate the dosing volume for the herbicide treatment. Volunteers from the IRPCLA provided numerous temperature profiles in the days and weeks leading up to the whole-lake herbicide treatment on the Chain. Based on the temperature profiles collected before the treatment, the expected mixing zone was determined to be approximately within the top of the metalimnion and was used for the final treatment dosing strategy (Figure 1.4-1, red dotted line). Onterra staff conducted a water discharge survey within the corridor under HWY H that separates the four upper lakes and the two lower lakes. Stream discharge is equal to water velocity multiplied by the cross-sectional area of where the water velocity was measured. The stream channel was 20 feet across where the cross-sectional discharge survey was performed; resulting in 20 subsections (1-foot wide each) being sampled. A measuring tape was secured the side of the channel, allowing the field staff to collect water depth and water velocity measurements at the center of each subsection across the channel (Photo 1.4-1).

Figure 1.4-1. Mixing zone of a stratified lake. Grey dashed line indicates start of metalimnion. Red dashed line indicates mixing volume used in dosing calculations.

Photo 1.4-1. Water discharge survey. Onterra, May 24, 2017.


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The cross sectional discharge survey yielded fairly uniform average subsection velocities of between 0.28 – 0.38 ft/sec (Figure 1.4-2). The discharge (Area x Ave. Velocity) of each subsection was added together, resulting in 13 ft3/sec or approximately 97 gallons/sec. These data assist with the understanding of achieved concentrations and exposure times, but were not used for altering the final dosing decisions.

Figure 1.4-2. Water discharge study results. May 24, 2017. Water velocity measurements (feet/sec) collected at 60% water depth. Map 2 displays the large-scale (aka whole-lake) herbicide treatment strategies designed for Buskey Bay, Lake Millicent, Hart Lake and Twin Bear Lake in 2017. The treatment includes application of liquid 2,4-D over 116.6 acres of the lakes. It was expected that the herbicide would mix throughout the entire epilimnion of each lake following the application, resulting in a target whole-lake epilimnetic 2,4-D concentration of 0.300 ppm ae. The herbicide treatments were conducted by Northern Aquatic Services on June 5-6, 2017 using a liquid formulation of 2,4-D amine (Shredder® Amine 4, WinField™). Twin Bear Lake and Hart Lake herbicide applications occurred on June 5, 2017 and Lake Millicent and Buskey Bay were treated on June 6, 2017. The applicator noted algae and pollen in the water as well as fish spawning activities during the application. 2.0 2017 MONITORING RESULTS

2.1 Herbicide Concentration Monitoring Results

BuskeyBay

Herbicide monitoring following the 2017 treatment found that the mean 1-7 DAT 2,4-D concentration in Buskey Bay was 0.367 ppm ae (Figure 2.1-2) and the initial concentration was closer to 0.405 ppm ae based on the modeled y-intercept of half-life analysis (Figure 2.1-1, 405 μg/L = 0.405 ppm). The 2,4-D linear half-life for Buskey Bay was 23 days, meaning that every 23 days, the herbicide is broken down in half of its original concentration. The concentrations varied somewhat between the sampling sites in the first days after treatment but were fairly uniform during the majority of the sampling intervals. This indicates that herbicide mixed fairly rapidly throughout the epilimnion of the lake including at site B1 where herbicide was not directly applied.

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The grey square symbol on Figure 2.1-2 represents water collected at 35 feet of water from Site B1 – Deep Hole. As discussed above, almost no herbicide is typically found below the epilimnion during a large-scale treatment program. A minimal amount of herbicide was observed in the hypolimnion of Buskey Bay in samples collected on 3 DAT and 21 DAT.

Figure 2.1-1. 2017 Buskey Bay 2-4,D half-life analysis Black line represents linear model (r2 = 0.87) and hashed lines represent 95% confidence intervals. Data provided by and used with permission from WDNR.

Figure 2.1-2. 2017 Buskey Bay Herbicide concentration monitoring results from three monitoring stations.

Temperature profiles collected before the treatment and at each herbicide concentration sampling interval indicate that the lake remained thermally stratified throughout the duration of the treatment. Limnologists, scientists that study inland waters, understand thermal stratification as occurring when there is a change of 1°C within 1 meter. The closely spaced water temperature contours on the isotherm (Figure 2.1-3, left frame) indicate a thermal gradient separating the epilimnion and hypolimnion beginning at approximately 13 feet on the treatment date and remaining stratified between about 13-15 feet through mid-July when the herbicide concentrations had degraded to a lower level. This can also be observed on the temperature profiles (Figure 2.1-3, right frame), where uniform temperatures were observed down to near 15 feet before getting much colder in a short amount of depth.

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Figure 2.1-3. Temperature isotherm (left) and profiles (right) collected from Buskey Bay following the 2017 herbicide treatment. Dashed line on isotherm represents treatment date. LakeMillicent

Herbicide monitoring found that the mean 1-7 DAT 2,4-D concentration in Lake Millicent was 0.578 ppm ae (Figure 2.1-5) and the initial concentration was closer to 0.597 ppm ae (Figure 2.1-4, 597 μg/L = 0.597 ppm) based on the modeled y-intercept of half-life analysis. The 2,4-D linear half-life for Lake Millicent was 25 days. The concentrations were variable during the beginning of the sampling before coming to more of an equilibrium between the three sampling sites during the later sampling intervals. The concentrations from site M1 were similar to concentrations at the other monitoring sites for the majority of the sampling intervals which suggests herbicide had mixed throughout the epilimnion of the lake to include site M1 where herbicide was not directly applied. A minimal amount of herbicide was detected in the hypolimnion of Lake Millicent in samples collected on 3 DAT and 21 DAT.

Figure 2.1-4. 2017 Lake Millicent 2-4,D half-life analysis Black line represents linear model (r2 = 0.72) and hashed lines represent 95% confidence intervals. Data provided by WDNR.

Figure 2.1-5. 2017 Lake Millicent Herbicide concentration monitoring results from three monitoring stations.

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Temperature profiles collected before the treatment and at each herbicide concentration sampling interval indicate that the lake remained thermally stratified throughout the duration of the sampling period. The closely spaced water temperature contours on the isotherm (Figure 2.1-6, left frame) indicate a thermal gradient beginning at approximately 12 feet on the treatment date and remaining stratified at around 15 feet through mid-July when the sampling concluded. This can also be observed on the temperature profiles (Figure 2.1-6, right frame).

Figure 2.1-6. Temperature Isotherm (left) and Profiles (right) Collected from Lake Millicent Following the 2017 Herbicide Treatment. Dashed line on isotherm represents treatment date. HartLake

Herbicide monitoring found that the mean 1-7 DAT 2,4-D concentration in Hart Lake was 0.518 ppm ae (Figure 2.1-8) and the initial concentration was closer to 0.531 ppm ae (Figure 2.1-7, 531 μg/L = 0.531 ppm) based on the modeled y-intercept of half-life analysis. The 2,4-D linear half-life for Hart Lake was 30 days. Herbicide concentrations varied somewhat between the three sampling sites initially and by 14 DAT showed little difference in concentrations between sites. Herbicide dissipation through the lake occurred over a relatively short time period as concentrations at site H2, where herbicide was not directly applied, were over 0.300 ppm ae on 1 DAT Very little herbicide was detected in the hypolimnion of Hart Lake in samples collected on 3 DAT and 21 DAT.

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Figure 2.1-7. 2017 Hart Lake 2-4,D half-life analysis Black line represents linear model (r2 = 0..64) and hashed lines represent 95% confidence intervals. Data provided by WDNR.

Figure 2.1-8. 2017 Hart Lake Herbicide concentration monitoring results from three monitoring stations.

Temperature profiles collected before the treatment and at each herbicide concentration sampling interval indicate that the lake remained thermally stratified throughout the duration of the sampling period. The closely spaced water temperature contours on the isotherm (Figure 2.1-9, left frame) indicate a thermal gradient beginning at approximately 12 feet on the treatment date and remaining stratified near 15 feet through mid-July. This can also be observed on the temperature profiles (Figure 2.1-9, right frame).

Figure 2.1-9. Temperature Isotherm (left) and Profiles (right) Collected from Hart Lake Following the 2017 Herbicide Treatment. Dashed line on isotherm represents treatment date.

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TwinBearLake

Herbicide monitoring found that the mean 1-7 DAT 2,4-D concentration in Twin Bear Lake was 0.357 ppm ae (Figure 2.1-11) and the initial concentration was closer to 0.398 ppm ae (Figure 2.1-10, 398 μg/L = 0.398 ppm) based on the modeled y-intercept of half-life analysis. The 2,4-D linear half-life for Twin Bear Lake was 20 days. Herbicide concentrations showed little variability between the three sampling sites over the course of the sampling intervals. The herbicide likely dissipated throughout the lake in a short period of time as concentrations at site T2, where herbicide was not directly applied, were of a similar level to the other sampling sites placed within application areas. A small amount of herbicide was detected in the hypolimnion of Twin Bear Lake in samples collected on 3 DAT and 21 DAT.

Figure 2.1-10. 2017 Twin Bear Lake 2-4,D half-life analysis Black line represents linear model (r2 = 0.98) and hashed lines represent 95% confidence intervals. Data provided by WDNR.

Figure 2.1-11. 2017 Twin Bear Lake Herbicide concentration monitoring results from three monitoring stations.

Temperature profiles collected after the treatment indicate that the lake remained thermally stratified throughout the duration of the sampling period. The closely spaced water temperature contours on the isotherm (Figure 2.1-12, left frame) indicate a thermal gradient beginning at approximately 12 feet on the treatment date and remaining stratified near 15 feet through mid-July. This can also be observed on the temperature profiles (Figure 2.1-12, right frame).

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Figure 2.1-12. Temperature Isotherm (left) and Profiles (right) Collected from Twin Bear Lake Following the 2017 Herbicide Treatment. Dashed line on isotherm represents treatment date. Eagle&FlynnLakes

Herbicide concentration monitoring was conducted in Eagle and Flynn Lakes in association with the 2017 herbicide treatments on the upstream lakes in the Pike Chain of Lakes. These data show that dissipation of herbicide out of the treated lakes occurred as detectable levels of herbicide was confirmed in Eagle and Flynn Lakes in the time period after the treatment. Note that the scale of the y-axis on Figure 2.1-13 is 10 times lower at the top of the graph at 0.100 ppm compared to 1.00 ppm on the graphs displayed above for the lakes in which herbicide was directly applied. At levels below 0.04 ppm ae in each sample collected from Eagle and Flynn Lakes, impacts to the aquatic plant community are not expected to have occurred.

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Figure 2.1-13. 2017 2,4-D Herbicide Concentration Monitoring Results for Eagle and Flynn Lakes of the Pike Chain of Lakes. Herbicide was not directly applied in Eagle or Flynn Lakes. Large-scale 2,4-D applications occurred in upstream lakes.

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The average 1-7 DAT average herbicide concentration is often used by lake managers as predictor of invasive milfoil control and associated native plant impacts (Figure 2.1-14). Typical whole-lake treatment EWM strategies target whole-lake concentrations between 0.275 and 0.400 ppm ae, balancing “acceptable” short-term impacts to the native plant community with a high level of control of EWM. Concentrations below 0.275 ppm ae have provided short-term EWM control, but a relatively quick population recovery. In lakes that have achieved average 1-7 DAT concentrations above 0.4 ppm ae, 90-100% EWM control was observed. However, this was coupled in most instances with high level of native plant damage, some of which has not recovered 4-5 years following the treatment. Figures 2.1-15 shows the mean 2,4-D concentrations that resulted from the 2017 large-scale treatments on the Buskey Bay, Lake Millicent, Hart Lake and Twin Bear Lake. Post-treatment herbicide concentration monitoring began one day after the completion of the herbicide applications which were completed over the course of two days from June 5 & June 6, 2017. Thus, all one day after treatment (DAT) samples from each lake were collected on June 7, 2017. The measured concentrations from Buskey Bay and Twin Bear Lake were near the target concentrations initially and had degraded to approximately 0.100 ppm or less by 35 DAT (Figure 2.1-15). The concentrations in Lake Millicent and Hart Lake were initially above the target application rate and persisted at above 0.250 ppm through the last sampling interval on 35 DAT (Figure 2.1-15).

Figure 2.1-14. Observed 1-7 DAT (Days after Treatment) 2,4-D concentrations on the Pike Chain of Lakes. Categories modified from Nault et al, 2012.

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April 2018 15

2.2 Point-Intercept Survey Results

Onterra ecologists completed point-intercept surveys on all of the Pike Chain of Lakes (except McCarry Lake) on August 28-31, 2017. The point-intercept survey data is compared to previous surveys conducted in 2013 & 2016 and is used to quantitatively assess the EWM and native plant populations’ response to the large scale herbicide treatment during the year-of-treatment. The 2017 point-intercept survey was approved by the IRPCLA to detect changes in the plant community during the year of treatment, and was paid for by the IRPCLA outside of the grant budget. Understanding the aquatic plant populations in 2017 is important, however an insufficient amount of time has passed since the herbicide control actions to determine if the treatments met the control success criteria. The point-intercept survey will be replicated in 2018 to evaluate the 2017 control strategy during the year-after-treatment. Figure 2.2-1 displays the littoral frequency of occurrence for EWM between the three point-intercept surveys. A statistically valid decrease in the EWM littoral frequency of occurrence (LFOO) from 2016-2017 was observed in each of the four lakes that had large-scale herbicide control actions in the spring of 2017. The EWM LFOO decreased from 6.3% in 2016 to 2.3% in 2017 in Buskey Bay representing a 62.4% decrease between the two surveys. Lake Millicent saw an EWM LFOO decrease from 13.7% in 2016 to 0% in 2017 (-100%). In Hart Lake, the EWM LFOO decreased from 10.0% in 2016 to 0% in 2017 (-100%). In Twin Bear Lake, the EWM LFOO decreased from 9.4% in 2016 to 2.0% in 2017 (-78.6%).

Figure 2.1-15. Mean 2,4-D Herbicide Concentration Results following the 2017 large-scale herbicide treatments in Buskey Bay, Lake Millicent, Hart Lake and Twin Bear Lake of the Pike Chain of Lakes.

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April 2018 16

Along with understanding the level of EWM control achieved from the control strategy, the point-intercept data will also allow an understanding of non-target native plant impacts from the treatment. Some species that are morphologically similar and sometimes difficult to identify in the field are combined for analysis purposes. Within the analysis, the collective occurrences of small pondweed (Potamogeton pusillus) and slender pondweed (Potamogeton berchtoldii) are combined. EWM is a dicot (broad-leaved plant) and the herbicides (2,4-D) used in the Pike Chain of Lakes in an effort to control EWM were historically believed to only have impacts to dicot species. Research conducted by the US Army Corps of Engineers, the WDNR, and private consultants have shown that certain non-dicot native plants are sensitive as well. Figure 3.2-1 shows how the dicot species in the treated lakes have changed over the course of the monitoring. Following the herbicide treatment, the LFOO of coontail was statistically unchanged or statistically higher in occurrence compared to 2016 (Figure 2.2-2). The populations of northern watermilfoil were statistically lower in each of the four treated lakes in 2017 compared to 2016.

Buskey Bay Lake Millicent

Hart Lake Twin Bear Lake

Figure 2.2-1. Littoral frequency of occurrence of EWM in Buskey Bay, Lake Millicent, Hart Lake and Twin Bear Lake from 2013-2017. Open circle represents statistically valid change from previous survey (Chi-Square α = 0.05). Dashed line indicates whole-lake herbicide treatment.

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April 2018 17

Coontail (Ceratophyllum demersum) Northern water milfoil (Myriophyllum sibiricum)

Figure 2.2-2. Littoral occurrence of select dicot aquatic plant species common in the Pike Chain of Lakes. Open circle represents a statistically valid change in occurrence from previous survey (Chi-square α = 0.05). Grey-dashed line indicates whole-lake herbicide treatment. Figure 2.2-3 displays the littoral occurrences of two native monocot species commonly found in the Pike Chain of Lakes that research has shown to be susceptible to many large-scale 2,4-D treatments. Slender naiad is an annual that relies on seed production and has been shown to be particularly susceptible to auxin herbicides (e.g. 2,4-D, triclopyr). Slender naiad and small/slender pondweed populations exhibited a statistically valid decrease in LFOO from 2016-2017 in Hart Lake but were not statistically different in Lake Millicent, Twin Bear Lake or Buskey Bay.

Slender naiad (Najas flexilis) Small/Slender pondweed (Potamogeton pusillus/P.

berchtoldii)

Figure 2.2-3. Littoral occurrence of select aquatic plant species susceptible to large-scale herbicide treatments and common in the Pike Chain of Lakes. Open circle represents a statistically valid change in occurrence from previous survey (Chi-square α = 0.05). Grey-dashed lines indicate whole-lake herbicide treatment. Figure 2.2-4 displays the littoral frequencies of four additional species that are amongst the most commonly encountered species in the Pike Chain of Lakes. No statistically valid declines from

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April 2018 18

2016-2017 were documented for fern-leaf pondweed, common waterweed, muskgrasses or variable-leaf pondweed. A statistically valid increase in LFOO from 2016-2017 was observed for common waterweed in Twin Bear Lake and for fern-leaf pondweed, variable-leaf pondweed and muskgrasses in Hart Lake. A chi-square analysis for all species identified in the point-intercept surveys is included as an appendix to this report (Appendix A).

Fern-leaf pondweed (Potamogeton robbinsii) Common waterweed (Elodea canadensis)

Muskgrasses (Chara spp.) Variable-leaf pondweed (Potamogeton gramineus)

Figure 2.2-4. Littoral occurrence of select aquatic plant species common in the Pike Chain of Lakes. Open circle represents a statistically valid change in occurrence from previous survey (Chi-square α = 0.05). Grey-dashed lines indicate whole-lake herbicide treatment. Figure 2.2-5 shows a semi-quantitative analysis of the abundance of natives through looking at total rake fullness ratings (i.e. how full of plants is the sampling rake at each location). Overall, the total rake fullness ratings in each of the treated lakes were found to be relatively similar between 2016 and 2017. It is important to note that the aquatic plant density in 2017 is mostly comprised of native plant species, whereas EWM was a major contributor to the aquatic plant biomass in 2016.

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April 2018 19

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Figure 2.2-5. Buskey Bay, Lake Millicent, Hart Lake and Twin Bear Lake total rake fullness ratings from 2013, 2016 & 2017 point-intercept surveys. Green dashed line represents large-scale 2,4-D herbicide treatment.

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April 2018 20

2.3 Late-Summer 2017 EWM Peak-Biomass Survey Results

Onterra ecologists visited the Pike Chain of Lakes on August 29-31, 2017 to conduct the Late-Summer EWM Peak-Biomass Survey to map the EWM population at its peak growth stage and to qualitatively assess the large-scale treatments. During the survey, the entire littoral areas of Eagle, Flynn and McCarry Lakes were surveyed, whereas the survey of the four lakes that underwent large-scale treatments focused on areas known to historically contain EWM colonies from previous surveys as well as locations in which EWM was observed during the completion of the 2017 point-intercept survey earlier in the week. The EWM population mapped in Buskey Bay during the late-summer 2017 survey was found to be much lower than pre-treatment levels observed in 2016. A relatively small scattered EWM colony was located along the west shore of the lake along with a few isolated occurrences mapped elsewhere in the lake (Figure 2.3-1).

Late-Summer 2016 (Pretreatment) Late-Summer 2017 (Post Treatment)

Figure 2.3-1. Buskey Bay 2016 Pre- and 2017 Post- herbicide treatment EWM mapping survey results.

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April 2018 21

No EWM was located in Lake Millicent or Hart Lakes during the late-summer 2017 EWM mapping survey (Figure 2.3-2 & 2.3-3 & Photo 2.3-1)


Figure 2.3-2. Lake Millicent 2016 Pre- and 2017 Post-treatment EWM survey results.


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Photograph 2.3-1 EWM colony in Lake Millicent before (2016, left) and after (2017, right) the large-scale herbicide treatment. (Photos by Onterra, LLC)


April 2018 22


Figure 2.3-3. Hart Lake 2016 Pre- and 2017 Post- herbicide treatment EWM mapping survey results. The EWM population in Twin Bear Lake was found to have decreased compared to the previous survey following the 2017 herbicide treatment. Two relatively small scattered EWM colonies as well as several single or few plants or clumps of plants were located along the western portion of the lake within one of the herbicide application areas from the treatment (Figure 2.3-4).


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April 2018 23


Figure 2.3-4. Twin Bear Lake 2016 Pre- and 2017 Post- herbicide treatment EWM mapping survey results. It is possible that more EWM persisted in the treated lakes in 2017 than was mapped during the survey; however, the EWM was impacted from the treatment and any plants that were beginning to recover from the treatment were likely small in stature and not able to be mapped using typical visual surveying methodologies. The decrease in colonized EWM acreage from 2016 to 2017 met the success criteria for the year of treatment, however, surveys conducted in 2018 will allow for a better understanding of EWM control one year after treatment.


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April 2018 24

Onterra ecologists also completed an EWM mapping survey of McCarry Lake on August 29, 2017 following the recent discovery of EWM in the lake by IRPCLA members. The mapping survey found colonized EWM consisting of highly scattered, scattered and dominant densities present in the lake (Figure 2.3-5). The majority of the EWM population in the lake was located along the eastern end of the lake. The EWM mapping survey results for Eagle and Flynn Lakes are included within the following report section (3.0). 3.0 HAND-HARVESTING ACTIVITIES – EAGLE & FLYNN LAKES

A set of EWM mapping surveys were used within this project to coordinate and qualitatively monitor the hand-harvesting efforts (Figure 3.0-1). The first monitoring event on Eagle Lake and Flynn Lake in 2017 was the Early Season Aquatic Invasive Species Survey (ESAIS). This late-spring/early-summer survey provides an early look at the lake to help guide the hand-harvesting management to occur on the system. Following the hand-harvesting, Onterra ecologists completed the Late-Summer EWM Peak-Biomass Survey, the results of which serve as a post-harvesting assessment of the hand-removal efforts. The hand-removal program would be considered successful if the density of EWM within the targeted areas was found to have remained approximately the same or decreased from the ESAIS Survey to the Late-Summer Peak-Biomass Survey.

Figure 2.3-5. McCarry Lake 2017 EWM mapping survey results.

Figure 3.0-1. Hand-Harvesting timeline diagram.


April 2018 25

3.1 ESAIS Survey Results (Pre Hand-Harvesting)

Onterra ecologists completed the ESAIS survey on July 10-11, 2017. The field crew noted favorable conditions with mostly sunny skies, light winds and excellent visibility. The ESAIS survey was limited to mapping EWM in Eagle and Flynn Lakes in order to finalize the hand-harvesting strategy. Three colonized areas consisting of scattered, dominant, and highly dominant densities of EWM were mapped as well as several additional low density point-based mapping occurrences including scattered single or few plants and a few clumps of plants and small plant colonies (Map 3). Only low density, point-based mapping occurrences of EWM consisting of a few single or few plants and one clump of plants was located in Flynn Lake during the survey (Map 3). Onterra provided the spatial data from this survey to the professional hand-harvesting firm to aid the control efforts. The final hand-harvesting strategy included targeting five sites with the highest density of EWM totalling 3.9 acres in Eagle Lake for removal by utilizing Diver Assisted Suction Harvesting (DASH) (Map 3). The IRPCLA contracted with TSB Lakefront Restoration and Diving, LLC (TSB) to conduct professional hand-harvesting of EWM in Eagle Lake in 2017. Professional hand-harvesting actions were undertaken over the course of three days at four of the five permitted harvest sites in Eagle Lake. 3.2 Late-Summer 2017 EWM Survey Results (Post Hand-Harvesting)

The late-summer EWM Peak-Biomass Survey was conducted on August 29-31, 2017 to qualitatively assess the hand harvesting efforts as well as to understand the peak growth (peak-biomass) of the EWM population throughout the lake and to determine an appropriate control strategy for the following year. During the survey, the hand-harvesting sites in Eagle Lake were evaluated for control. The professional hand-harvesting efforts conducted on Eagle Lake in 2017 were focused at four main areas of the lake where the largest known concentrations of EWM were located and are displayed on Figures 3.2-1 through 3.2-3. The late-summer survey found the EWM population in Eagle Lake to be similar to or slightly less than the early-summer survey. Most of the EWM population in Eagle Lake consisted of widely spread, low density occurrences. A few dense, but relatively small EWM colonies were located at a few sites in Eagle Lake (Map 4). The EWM population in Flynn Lake consisted of a small concentration of single or few plants and clumps of plants concentrated near the outlet of the lake in addition to a few occurrences on the northern end of the lake (Map 4).


April 2018 26

SiteA‐17

Following the hand-harvesting efforts in site A-17, the EWM population was found to be of a lower size and density than in the pre-harvesting survey (Figure 3.2-1). Control efforts in site A-17 resulted in a reduction of the EWM population and met control expectations for the site.

SiteB‐17Following the hand-harvesting efforts in site B-17, the highly dominant colony delineated in the center of the site in July was reduced to a number of point-based EWM occurrences; however scattered and dominant EWM colonies were present on the margins of the harvesting site during the late-summer survey (Figure 3.2-2). The hand-harvesting efforts in site B-17 during 2017 resulted in a reduction in density of the main colony in the site, however, fell short of achieving EWM throughout the entirety of the site.

July 2017 Pre-Hand Harvesting August 2017 Post-Hand Harvesting

Figure 3.2-1. July 2017 pre- and August 2017 Post- Professional Hand-Harvesting EWM Survey Results-in Eagle Lake Site A-17.


April 2018 27

SitesC‐17,D‐17&E‐17

The dominant EWM colony in C-17 was reduced to point-based EWM occurrences following the harvesting efforts (Figure 3.2-3, top frames). Following harvesting efforts in site D-17, the EWM population was reduced from clumps of plants or small plant colonies to single or few plant occurrences (Figure 3.2-3, middle frames). No harvesting efforts were undertaken in site E-17 during 2017, likely due to a lack of available time. The EWM population in site E-17 was found to have increased in density from dominant to highly dominant between the early and late-summer mapping surveys (Figure 3.2-3, bottom frames).

July 2017 Pre-Hand Harvesting

August 2017 Post-Hand Harvesting

Figure 3.2-2. July 2017 pre- and August 2017 Post- Professional Hand-Harvesting EWM Survey Results-in Eagle Lake Site B-17.


April 2018 28

July 2017 Pre-Hand Harvesting August 2017 Post-Hand Harvesting

Figure 3.2-3. July 2017 pre- and August 2017 Post- Professional Hand-Harvesting EWM Survey Results-in Eagle Lake Sites C-17, D-17 & E-17. (No harvesting efforts occurred in site E-17.)


April 2018 29

4.0 CONCLUSIONS AND DISCUSSION

4.1 2017 Summary

The large-scale treatment and associated monitoring in 2017 was carried out as planned with measured herbicide concentrations being slightly above target concentrations. Herbicide persistence was longer than anticipated in Lake Millicent and Hart Lake with concentrations exceeding the irrigation threshold (0.1 ppm ae) through the end of the monitoring at 35 DAT. Herbicide degradation patterns in Buskey Bay and Twin Bear Lake showed a degradation pattern closer to anticipated rates, however detectable 2,4-D remained present in each lake at the conclusion of monitoring on 35 DAT. Water discharge calculations indicate approximately 7% epilimnetic volume loss after one week, which suggests that some, but minimal herbicide movement downstream into Eagle and Flynn Lakes would occur. It should be noted that due to precipitation events before the May 24, 2017 data collection, actual discharge volumes may have been less than estimated. Although the flow monitoring in 2017 provided some estimate of water exchange, additional flow data would be needed for more accurate discharge calculations. The herbicide concentration monitoring in Eagle and Flynn Lakes showed detectable levels of 2,4-D, however the measured concentrations are believed to have been too low to cause any discernible impacts on the aquatic plant community in these lakes. The 2017 large-scale treatment was highly effective on controlling EWM, with no EWM being located during late-summer surveys (point-intercept and meander-based mapping) in Lake Millicent or Hart Lakes and large EWM decreases documented in Buskey Bay and Twin Bear Lakes. While some impacts to the native aquatic plant community were noted, the magnitude of decline was less than anticipated by Onterra. Point-intercept surveys conducted in 2018 will allow a better understanding of aquatic plant recovery and longer term trends. Professional hand-harvesting efforts in Eagle Lake in 2017 resulted in decreases in EWM in the targeted areas; however, were not able to impact the EWM population on a lake-wide scale. The EWM population in Eagle Lake in 2017 was similar to levels observed in 2016 with widely scattered plants that consist mostly of low density occurrences. The point-intercept survey found an EWM LFOO of just 0.5% supporting the mapping data in showing the overall population to be fairly low in the lake. 4.2 2018 Proposed EWM Control & Monitoring Strategy

The WDNR and IRPCLA adopted an aggressive approach to EWM management as a part of a January 2016 addendum to their Comprehensive Management Plan. Few lakes in Bayfield County contain EWM and the local WDNR supports aggressive management of existing populations which may lessen the chance of EWM spreading to other waterbodies. The newly adopted strategy to EWM management led to the completion of whole-lake herbicide treatments in 2017. Consistent with this strategy, the WDNR and IRPCLA would like to continue an active EWM management program moving forward that targets the remaining EWM population in the system. Based on the known populations observed in the Pike Chain of Lakes during the late-summer 2017 mapping survey, an integrated approach to EWM control that utilizes spot-herbicide treatments and professional hand-harvesting was developed for 2018. The large-scale herbicide treatments in 2017 were under the budget included within the grant funded


April 2018 30

project and the IRPCLA would like to utilize the surplus funds, along with existing ear-marked funds, to complete EWM control activities in 2018. HerbicideSpot‐TreatmentControlStrategy

One site in Buskey Bay and one site in Twin Bear Lake were identified as locations in which the EWM population could be considered for herbicide control in 2018. Onterra believes that a 2,4-D treatment is not likely to be effective in the proposed sites due to the relatively small treatment area size (2 acres) and exposed location of the sites. Control of EWM with small spot treatments (working definition is less than 5 acres) is less likely to be effective due to rapid herbicide dissipation. Ongoing field trials are assessing the efficacy (EWM control) and selectivity (collateral native plant impacts) of herbicides that may be effective with a shorter exposure time such as diquat or herbicide combinations (diquat/endothall, 2,4-D/endothall, etc.). Three treatment options were discussed with the IRPCLA and local WDNR Lakes Coordinator: 1) diquat, 2) combination 2,4-D/endothall, and 3) combination diquat/endothall. The 2,4-D/endothall combination was considered the option with the longest exposure time required. Diquat is a contact herbicide that does not translocate through the plant tissue (i.e. systemic activity) and thus some concern exists that only the exposed portions of the plants are affected leaving the root crowns intact and capable of recovering. Diquat has a 2 gallon/surface acre maximum application rate. When mixed with the water volume in the proposed sites, the diquat concentrations (0.15-0.16 ppm) are lower than may be needed for control. Aquastrike® is a commercially available product that is comprised of a combination of diquat/endothall. When this product received EPA registration, it configured the use-rates volumetrically. This allows diquat to reach the target concentration (0.33 ppm) in all water depths. This concentration is approximately twice what could be achieved if using diquat alone (Table 4.2-1).

Table 4.2-1. 2018 Herbicide Treatment Scenarios: Diquat vs Diquat + endothall.

Another advantage of the Aquastrike® product is the endothall component. While diquat does not have systemic activity, endothall has proven to have a high level of systemic activity (i.e. moves throughout the plant, including into the root crown) at cold water temperatures. Within a recent United Phosphorus, Inc. (UPI) newsletter-style report, Dr. Scott Nissen (Colorado State University) is quoted, "We have data that confirms that endothall does translocate from shoots to root tissue. In fact, the ratio of endothall in the root vs. shoot tissue after 192 hours of exposure was greater for endothall than for other systemic herbicides that we have evaluated." The manufacturers of endothall, have shown that increased systemic activity of endothall occur when water temperatures are colder (<60°F).

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A-18 (Buskey Bay) 2.0 9.0 18.0 2.0 0.16 1.50 0.33 1.66B-18 (Twin Bear Lake) 2.0 10.0 20.0 2.0 0.15 1.50 0.33 1.66

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At this time, a combination diquat/endothall treatment is proposed for Buskey Bay (Map 5) and Twin Bear (Map 6) where a two-acre herbicide application area could be constructed with a sizable buffer. Prior to the treatment, these sites would be investigated to confirm EWM survival over the winter and refine the site boundaries if population expansion since the late summer of 2017 occurred. It is imperative that the herbicide treatment occur before surface temperatures reach 60°F as recommended by the manufacturer of endothall. In past years, herbicide treatment timing has corresponded with the conclusion of Native American walleye and muskellunge spearfishing activities and this may also be factored into the timing of the proposed treatment in 2018. A late-summer 2018 EWM mapping survey would serve to evaluate the herbicide control actions and be used to develop a monitoring and control plan for 2019. ProfessionalHand‐harvestingControlStrategy

It is recommended that the EWM population in the four upstream lakes that were treated in 2017 be considered for hand-harvesting activities. At this time, documented EWM occurrences have only been identified in Buskey Bay and Twin Bear. An Early-Season AIS Survey is scheduled to occur in June to locate additional rebounding EWM occurrences for hand-harvesting and finalize the overall hand-harvesting strategy. Diver Assisted Suction Harvesting (DASH) may be an appropriate control strategy for addressing EWM in some areas of the lake that contain colonized EWM, whereas traditional diving methods with scuba or snorkeling may be more appropriate for smaller sites. The EWM population in Eagle Lake during 2017 does not justify a large-scale (aka whole-lake) herbicide control strategy at this time. And the EWM population is not configured where herbicide spot treatments are likely to be an effective control strategy at this time. It is recommended to continue the hand-harvesting program in Eagle Lake during 2018, similar to what was conducted in 2017. The 2017 efforts proved effective where they were conducted; however, hand-harvesting alone will likely not reduce the lake-wide EWM population. If the EWM population in Eagle Lake shows an increase in 2018, consideration for enacting an herbicide control program in 2019 may be warranted. This may include large-scale or spot treatment herbicide control methods. A late-summer 2018 EWM mapping survey would serve to evaluate the hand-harvesting control actions and be used to develop a monitoring and control plan for 2019. McCarryLakeEWM

The WDNR has a non-competitive grant program that lakes with new AIS infestations (less than 5 years after detection) qualify for. The IRPCLA is in the process of putting together an AIS Early Detection and Response Grant application to fund a three-year EWM control and monitoring program. The IRPCLA discussed a number of potential control strategies to target the newly identified EWM population in McCarry Lake. An herbicide spot treatment on McCarry Lake is not applicable because at 32 acres, even a 3-acre spot treatment would have whole-lake impacts.


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DASH hand-harvesting may be applicable to the two dominant EWM colonies, but remaining plants are so scattered that the method is not applicable. It may be difficult or impossible to get a DASH onto the lake considering the undeveloped landing. This cursory analysis indicates the following possibilities; 1) no active management, but continued monitoring, 2) hand-harvesting with snorkelers/scuba (no DASH), and 3) a large-scale (aka whole-lake) treatment. The IRPCLA is trending towards pursuing a large-scale 2,4-D treatment of McCarry Lake in 2019. Continued investigation of the 2017 large-scale 2,4-D treatment on the Pike Chain of Lakes may result in a modified dosing strategy, but the current use-pattern being considered is to reach a lake-wide epilimnetic concentration of 0.300 ppm ae. Pretreatment aquatic plant data (EWM mapping survey and point-intercept survey) would be collected during 2018 and replicated in 2019 (year of treatment) and 2020 (year after treatment) for evaluation purposes. An acoustic bathymetric modeling survey (i.e. lake depth contour mapping) would take place in 2018 to understand potential mixing volumes for proper herbicide dosing. Postponing the large-scale effort until 2019 will allow the IRPCLA sufficient time to communicate and educate lake stakeholders on the proposed strategy.


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APPENDIX A

Table 1. Buskey Bay Chi-Square Analysis.

2013 2016 2017 % Change Direction % Change Direction

Myriophyllum spicatum Eurasian w atermilfoil 0.6 6.3 2.3 -62.4 ▼ 287.6 ▲Ceratophyllum demersum Coontail 37.6 38.5 41.9 9.0 ▲ 11.6 ▲Myriophyllum sibiricum Northern w atermilfoil 11.5 10.2 4.0 -60.5 ▼ -65.0 ▼Nymphaea odorata White w ater lily 4.2 3.0 3.4 13.3 ▲ -20.9 ▼Ranunculus aquatilis White w ater crow foot 3.9 2.3 1.3 -41.7 ▼ -65.9 ▼Bidens beckii Water marigold 3.0 3.0 0.3 -88.7 ▼ -88.9 ▼Utricularia vulgaris Common bladderw ort 0.9 0.7 1.0 53.0 ▲ 10.7 ▲Utricularia gibba Creeping bladderw ort 0.6 0.7 1.0 53.0 ▲ 66.1 ▲Nuphar variegata Spatterdock 0.6 0.7 0.3 -49.0 ▼ -44.6 ▼Myriophyllum tenellum Dw arf w atermilfoil 0.0 0.7 0.3 -49.0 ▼ ▲Brasenia schreberi Watershield 0.0 0.0 0.3 ▲ ▲Myriophyllum verticillatum Whorled w atermilfoil 0.3 0.0 0.0 - -100.0 ▼Ceratophyllum echinatum Spiny hornw ort 0.0 0.3 0.0 -100.0 ▼ -

Potamogeton crispus Curly-leaf pondw eed 0.0 0.0 0.0 - -Potamogeton robbinsii Fern-leaf pondw eed 37.3 40.5 45.0 11.1 ▲ 20.6 ▲Elodea canadensis Common w aterw eed 42.1 43.1 40.6 -5.8 ▼ -3.6 ▼Chara spp. Muskgrasses 21.2 22.7 25.8 13.8 ▲ 21.8 ▲Vallisneria americana Wild celery 13.9 17.1 17.8 4.0 ▲ 27.6 ▲Potamogeton pusillus & P. berchtoldii Small & Slender pondw ee 10.6 13.2 17.1 30.1 ▲ 61.4 ▲Potamogeton amplifolius Large-leaf pondw eed 15.2 10.5 14.4 37.1 ▲ -4.8 ▼Potamogeton gramineus Variable-leaf pondw eed 9.1 10.9 14.8 36.0 ▲ 62.4 ▲Potamogeton zosteriformis Flat-stem pondw eed 19.1 10.5 5.4 -49.0 ▼ -71.9 ▼Potamogeton praelongus White-stem pondw eed 7.0 11.8 6.7 -43.3 ▼ -3.7 ▼Potamogeton pusillus Small pondw eed 5.5 8.6 9.1 5.9 ▲ 66.1 ▲Potamogeton berchtoldii Slender pondw eed 5.2 4.6 8.4 82.2 ▲ 62.9 ▲Najas flexilis Slender naiad 5.2 5.6 4.0 -28.0 ▼ -21.8 ▼Potamogeton strictifolius Stif f pondw eed 9.1 3.6 1.7 -53.6 ▼ -81.5 ▼Heteranthera dubia Water stargrass 2.7 7.2 2.7 -62.9 ▼ -1.6 ▼Potamogeton foliosus Leafy pondw eed 1.8 3.6 2.7 -25.8 ▼ 47.7 ▲Potamogeton illinoensis Illinois pondw eed 2.4 2.0 1.7 -15.0 ▼ -30.8 ▼Potamogeton hybrid 1 Pondw eed Hybrid 1 0.0 0.0 3.4 ▲ ▲Nitella spp. Stonew orts 4.8 0.3 0.3 2.0 ▲ -93.1 ▼Eleocharis acicularis Needle spikerush 0.6 1.6 2.0 22.4 ▲ 232.2 ▲Potamogeton richardsonii Clasping-leaf pondw eed 0.3 0.7 2.0 206.0 ▲ 564.4 ▲Filamentous algae Filamentous algae 0.0 1.6 0.7 -59.2 ▼ ▲Fissidens spp. & Fontinalis spp. Aquatic Moss 0.0 0.3 1.3 308.1 ▲ ▲Potamogeton natans Floating-leaf pondw eed 0.9 0.3 0.3 2.0 ▲ -63.1 ▼Persicaria amphibia Water smartw eed 0.6 0.7 0.3 -49.0 ▼ -44.6 ▼Stuckenia pectinata Sago pondw eed 0.6 0.7 0.0 -100.0 ▼ -100.0 ▼Lemna turionifera Turion duckw eed 0.0 0.0 0.3 ▲ ▲Riccia fluitans Slender riccia 0.3 0.0 0.0 - -100.0 ▼Sparganium americanum American bur-reed 0.3 0.0 0.0 - -100.0 ▼Riccia fluitans Slender riccia 0.3 0.0 0.0 - -100.0 ▼Riccia sp. Riccia sp. 0.3 0.0 0.0 - -100.0 ▼Potamogeton friesii Fries' pondw eed 0.0 0.3 0.0 -100.0 ▼ -Potamogeton epihydrus Ribbon-leaf pondw eed 0.3 0.0 0.0 - -100.0 ▼Lemna trisulca Forked duckw eed 0.3 0.0 0.0 - -100.0 ▼Isoetes spp. Quillw ort spp. 0.0 0.3 0.0 -100.0 ▼ -Calla palustris Water arum 0.0 0.3 0.0 -100.0 ▼ -

▲ or ▼ = Change Not Statistically Valid (Chi-square; α = 0.05)

2013-2017

Dic

ots

No

n-d

ico

ts

▲ or ▼ = Change Statistically Valid (Chi-square; α = 0.05)

Scientific Name Common Name

LFOO (%) 2016-2017


April 2018 34

Table 2. Lake Millicent Chi-Square Analysis.


Myriophyllum spicatum Eurasian w atermilfoil 0.9 13.7 0.0 -100.0 ▼ -100.0 ▼Ceratophyllum demersum Coontail 9.0 9.3 9.5 1.9 ▲ 4.6 ▲Myriophyllum tenellum Dw arf w atermilfoil 3.6 4.9 5.8 18.4 ▲ 59.2 ▲Myriophyllum sibiricum Northern w atermilfoil 7.2 8.4 0.0 -100.0 ▼ -100.0 ▼Ranunculus aquatilis White w ater crow foot 5.0 7.1 0.8 -88.4 ▼ -83.5 ▼Nymphaea odorata White w ater lily 1.8 0.4 1.6 272.0 ▲ -9.1 ▼Utricularia vulgaris Common bladderw ort 0.9 0.0 1.6 ▲ 81.9 ▲Ceratophyllum echinatum Spiny hornw ort 0.0 2.2 0.4 -81.4 ▼ ▲Bidens beckii Water marigold 1.4 1.8 0.0 -100.0 ▼ -100.0 ▼Utricularia intermedia Flat-leaf bladderw ort 0.5 0.4 0.8 86.0 ▲ 81.9 ▲Utricularia minor Small bladderw ort 0.0 0.0 0.8 ▲ ▲Brasenia schreberi Watershield 0.9 0.0 0.4 ▲ -54.5 ▼Utricularia gibba Creeping bladderw ort 0.9 0.4 0.0 -100.0 ▼ -100.0 ▼Nuphar variegata Spatterdock 0.0 0.0 0.4 ▲ ▲Ranunculus flammula Creeping spearw ort 0.5 0.0 0.0 - -100.0 ▼

Potamogeton crispus Curly-leaf pondw eed 0.0 0.0 0.0 - -Chara spp. Muskgrasses 26.2 21.7 29.2 34.8 ▲ 11.3 ▲

Potamogeton gramineus Variable-leaf pondw eed 33.0 20.8 24.7 18.7 ▲ -25.2 ▼Elodea canadensis Common w aterw eed 19.5 16.8 20.6 22.4 ▲ 5.8 ▲Vallisneria americana Wild celery 11.8 15.5 18.1 16.9 ▲ 53.9 ▲Potamogeton pusillus & P. berchtoldii Small & Slender pondw ee 17.2 12.8 14.8 15.5 ▲ -13.8 ▼Potamogeton pusillus Small pondw eed 15.4 12.8 5.3 -58.3 ▼ -65.2 ▼Eleocharis acicularis Needle spikerush 9.0 9.7 7.4 -23.9 ▼ -18.1 ▼Potamogeton robbinsii Fern-leaf pondw eed 6.3 6.2 6.2 -0.4 ▼ -2.6 ▼Najas flexilis Slender naiad 6.3 5.3 6.2 16.3 ▲ -2.6 ▼Nitella spp. Stonew orts 1.4 3.5 8.6 144.1 ▲ 536.6 ▲Potamogeton berchtoldii Slender pondw eed 1.8 0.0 9.5 ▲ 422.9 ▲Heteranthera dubia Water stargrass 5.4 5.3 0.0 -100.0 ▼ -100.0 ▼Potamogeton illinoensis Illinois pondw eed 1.4 7.1 0.8 -88.4 ▼ -39.4 ▼Potamogeton amplifolius Large-leaf pondw eed 1.8 1.3 3.3 148.0 ▲ 81.9 ▲Potamogeton strictifolius Stif f pondw eed 3.2 1.8 0.0 -100.0 ▼ -100.0 ▼Potamogeton richardsonii Clasping-leaf pondw eed 3.2 0.0 0.8 ▲ -74.0 ▼Potamogeton foliosus Leafy pondw eed 0.0 4.0 0.4 -89.7 ▼ ▲Schoenoplectus subterminalis Water bulrush 0.9 0.4 1.2 179.0 ▲ 36.4 ▲Potamogeton praelongus White-stem pondw eed 0.0 2.7 0.4 -84.5 ▼ ▲Filamentous algae Filamentous algae 0.0 2.2 0.4 -81.4 ▼ ▲Fissidens spp. & Fontinalis spp. Aquatic Moss 2.7 0.0 0.0 - -100.0 ▼Schoenoplectus acutus Hardstem bulrush 0.5 0.0 0.8 ▲ 81.9 ▲Potamogeton zosteriformis Flat-stem pondw eed 0.9 0.9 0.0 -100.0 ▼ -100.0 ▼Potamogeton hybrid 2 Pondw eed Hybrid 2 0.0 0.0 0.8 ▲ ▲Potamogeton natans Floating-leaf pondw eed 0.5 0.0 0.4 ▲ -9.1 ▼Schoenoplectus tabernaemontani Softstem bulrush 0.0 0.9 0.0 -100.0 ▼ -Freshwater sponge Freshw ater sponge 0.0 0.0 0.4 ▲ ▲Potamogeton epihydrus Ribbon-leaf pondw eed 0.5 0.0 0.0 - -100.0 ▼Juncus pelocarpus Brow n-fruited rush 0.5 0.0 0.0 - -100.0 ▼


2013-2017

Dic

ots

No

n-d

ico

ts



LFOO (%) 2016-2017


April 2018 35

Table 3. Hart Lake Chi-Square Analysis.


Myriophyllum spicatum Eurasian w atermilfoil 0.9 10.0 0.0 -100.0 ▼ -100.0 ▼Ceratophyllum demersum Coontail 5.9 2.7 6.7 151.9 ▲ 12.7 ▲Myriophyllum sibiricum Northern w atermilfoil 1.6 3.9 0.2 -95.0 ▼ -87.4 ▼Nuphar variegata Spatterdock 2.2 1.2 1.2 -5.6 ▼ -46.0 ▼Ceratophyllum echinatum Spiny hornw ort 0.9 1.9 1.6 -16.0 ▼ 67.9 ▲Myriophyllum tenellum Dw arf w atermilfoil 0.6 1.2 1.0 -21.3 ▼ 57.4 ▲Nymphaea odorata White w ater lily 1.4 0.5 0.8 67.9 ▲ -44.0 ▼Utricularia vulgaris Common bladderw ort 0.3 0.2 0.8 403.7 ▲ 151.9 ▲Brasenia schreberi Watershield 0.6 0.8 0.2 -74.8 ▼ -68.5 ▼Bidens beckii Water marigold 0.6 0.6 0.2 -68.5 ▼ -68.5 ▼Utricularia gibba Creeping bladderw ort 0.3 0.2 0.0 -100.0 ▼ -100.0 ▼Ranunculus aquatilis White w ater crow foot 0.2 0.2 0.0 -100.0 ▼ -100.0 ▼Utricularia minor Small bladderw ort 0.2 0.0 0.0 - -100.0 ▼Ranunculus flammula Creeping spearw ort 0.2 0.0 0.0 - -100.0 ▼

Potamogeton crispus Curly-leaf pondw eed 0.0 0.0 0.0 - -Chara spp. Muskgrasses 27.9 28.4 38.3 34.9 ▲ 37.2 ▲Potamogeton gramineus Variable-leaf pondw eed 14.2 15.0 20.2 35.1 ▲ 42.5 ▲Elodea canadensis Common w aterw eed 13.3 15.9 12.2 -23.5 ▼ -8.1 ▼Potamogeton robbinsii Fern-leaf pondw eed 10.0 11.1 15.9 43.7 ▲ 59.4 ▲Potamogeton pusillus & P. berchtoldii Small & Slender pondw ee 14.4 11.2 4.9 -56.3 ▼ -65.8 ▼Nitella spp. Stonew orts 5.1 8.4 11.4 35.3 ▲ 121.3 ▲Najas flexilis Slender naiad 8.9 12.3 4.1 -66.5 ▼ -53.6 ▼Potamogeton pusillus Small pondw eed 14.0 6.6 4.1 -37.0 ▼ -70.6 ▼Vallisneria americana Wild celery 2.5 3.6 5.3 47.8 ▲ 112.5 ▲Potamogeton amplifolius Large-leaf pondw eed 4.2 3.0 3.5 19.3 ▲ -16.0 ▼Potamogeton praelongus White-stem pondw eed 2.3 2.7 2.6 -3.7 ▼ 9.1 ▲Eleocharis acicularis Needle spikerush 1.1 1.7 2.8 60.3 ▲ 151.9 ▲Potamogeton berchtoldii Slender pondw eed 0.3 4.7 0.8 -83.2 ▼ 151.9 ▲Potamogeton strictifolius Stif f pondw eed 1.1 5.0 0.0 -100.0 ▼ -100.0 ▼Potamogeton zosteriformis Flat-stem pondw eed 1.4 1.7 0.6 -65.7 ▼ -58.0 ▼Filamentous algae Filamentous algae 0.0 2.0 1.0 -51.6 ▼ ▲Heteranthera dubia Water stargrass 1.6 1.2 0.4 -68.5 ▼ -74.8 ▼Potamogeton illinoensis Illinois pondw eed 0.5 1.4 0.2 -86.0 ▼ -58.0 ▼Potamogeton foliosus Leafy pondw eed 0.2 1.4 0.4 -72.0 ▼ 151.9 ▲Schoenoplectus acutus Hardstem bulrush 0.6 0.3 0.6 88.9 ▲ -5.6 ▼Potamogeton richardsonii Clasping-leaf pondw eed 0.8 0.6 0.2 -68.5 ▼ -74.8 ▼Isoetes spp. Quillw ort spp. 0.3 0.6 0.0 -100.0 ▼ -100.0 ▼Potamogeton epihydrus Ribbon-leaf pondw eed 0.6 0.2 0.0 -100.0 ▼ -100.0 ▼Sagittaria sp. (rosette) Arrow head sp. (rosette) 0.0 0.6 0.0 -100.0 ▼ -Potamogeton natans Floating-leaf pondw eed 0.2 0.0 0.2 ▲ 25.9 ▲Spirodela polyrhiza Greater duckw eed 0.0 0.0 0.2 ▲ ▲Freshwater sponge Freshw ater sponge 0.0 0.0 0.2 ▲ ▲Typha spp. Cattail spp. 0.2 0.0 0.0 - -100.0 ▼

Juncus pelocarpus Brow n-fruited rush 0.0 0.2 0.0 -100.0 ▼ -Fissidens spp. & Fontinalis spp. Aquatic Moss 0.2 0.0 0.0 - -100.0 ▼


2013-2017

Dic

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No

n-d

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LFOO (%) 2016-2017


April 2018 36

Table 4. Twin Bear Lake Chi-Square Analysis.


Myriophyllum spicatum Eurasian w atermilfoil 0.3 9.4 2.0 -78.6 ▼ 606.4 ▲Ceratophyllum demersum Coontail 23.3 22.3 25.1 12.7 ▲ 7.7 ▲Myriophyllum sibiricum Northern w atermilfoil 6.5 12.1 4.0 -66.9 ▼ -38.6 ▼Bidens beckii Water marigold 1.1 4.7 0.3 -92.9 ▼ -70.6 ▼Ranunculus aquatilis White w ater crow foot 0.9 1.6 1.7 7.0 ▲ 96.2 ▲Nuphar variegata Spatterdock 0.9 0.8 0.7 -14.4 ▼ -21.5 ▼Nymphaea odorata White w ater lily 0.6 0.0 0.7 ▲ 17.7 ▲Myriophyllum tenellum Dw arf w atermilfoil 0.0 0.4 0.7 71.2 ▲ ▲Ceratophyllum echinatum Spiny hornw ort 0.6 0.0 0.3 ▲ -41.1 ▼

Potamogeton crispus Curly-leaf pondw eed 0.0 0.0 0.0 - -Elodea canadensis Common w aterw eed 29.8 29.3 38.1 30.1 ▲ 27.8 ▲Potamogeton robbinsii Fern-leaf pondw eed 21.0 32.0 33.8 5.5 ▲ 60.7 ▲Potamogeton pusillus & P. berchtoldii Small & Slender pondw ee 15.1 19.1 23.1 20.6 ▲ 53.3 ▲Chara spp. Muskgrasses 15.9 18.4 22.1 20.2 ▲ 38.7 ▲Potamogeton gramineus Variable-leaf pondw eed 11.4 14.5 15.7 8.8 ▲ 38.3 ▲Najas flexilis Slender naiad 9.9 13.3 11.7 -11.9 ▼ 17.7 ▲Potamogeton berchtoldii Slender pondw eed 10.2 0.0 15.7 ▲ 53.7 ▲Potamogeton pusillus Small pondw eed 4.8 19.1 7.4 -61.6 ▼ 52.4 ▲Heteranthera dubia Water stargrass 5.4 1.6 4.3 178.3 ▲ -19.5 ▼Potamogeton amplifolius Large-leaf pondw eed 3.7 2.7 4.0 46.8 ▲ 8.7 ▲Potamogeton zosteriformis Flat-stem pondw eed 5.4 2.7 2.7 -2.2 ▼ -50.4 ▼Vallisneria americana Wild celery 1.7 3.1 4.0 28.4 ▲ 135.5 ▲Filamentous algae Filamentous algae 0.0 12.5 0.0 -100.0 ▼ -Potamogeton richardsonii Clasping-leaf pondw eed 1.4 1.6 3.7 135.5 ▲ 159.0 ▲Potamogeton praelongus White-stem pondw eed 0.3 2.3 3.3 42.7 ▲ 1077.3 ▲Potamogeton strictifolius Stif f pondw eed 1.4 4.7 1.0 -78.6 ▼ -29.4 ▼Eleocharis acicularis Needle spikerush 0.3 0.8 2.3 199.7 ▲ 724.1 ▲Potamogeton illinoensis Illinois pondw eed 0.3 1.2 0.3 -71.5 ▼ 17.7 ▲Potamogeton foliosus Leafy pondw eed 0.0 0.0 1.0 ▲ ▲Potamogeton hybrid 1 Pondw eed Hybrid 1 0.0 0.0 1.0 ▲ ▲Lemna trisulca Forked duckw eed 0.0 0.8 0.7 -14.4 ▼ ▲Potamogeton epihydrus Ribbon-leaf pondw eed 1.1 0.4 0.0 -100.0 ▼ -100.0 ▼Nitella spp. Stonew orts 0.0 0.0 0.7 ▲ ▲Isoetes spp. Quillw ort spp. 0.0 0.0 0.3 ▲ ▲Schoenoplectus acutus Hardstem bulrush 0.3 0.0 0.0 - -100.0 ▼Sagittaria cristata Crested arrow head 0.3 0.0 0.0 - -100.0 ▼Eleocharis palustris Creeping spikerush 0.3 0.0 0.0 - -100.0 ▼Fissidens spp. & Fontinalis spp. Aquatic Moss 0.0 0.4 0.0 -100.0 ▼ -


2013-2017

Dic

ots

No

n-d

ico

ts



LFOO (%) 2016-2017

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E1 - Deep Hole

T2 - Deep Hole

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M1 - Deep Hole

H2 - Deep Hole

.815 Prosper Road

De Pere, WI 54115920.338.8860

www.onterra-eco.com

2,000

Feet

Proposed TreatmentMonitoring Sample Plan

Pike Chain of LakesLegend

Sources:Roads and Hydro: WDNRBathymetry: Onterra, 2016Map Date: May 11, 2017Filename: BuskeyBay_T2017_EWM_Prelim1.mxd

k

Project Location in Wisconsin

Public Access"p

!(2017 HerbicideConcentration MonitoringLocations

Bayfield County, Wisconsin

Map 12017 Preliminary EWMTreatment Area

Interval Samples/interval Total Samples1 DAT 14 143 DAT 18* 325 DAT 14 467 DAT 14 6014 DAT 14 7421 DAT 18* 9228 DAT 14 10635 DAT 14 120*add hypolimnetic samples

Herbicide Sample Intervals

Lake Site Station ID Latitude Longitude Sample DepthB1 - Deep Hole 043071 46.531506 -91.371828 Integrated (0-6 ft)/Van Dorn (hypolimnetic)

B2 10048393 46.525938 -91.375369 Integrated (0-6ft)B3 10048394 46.524430 -91.380929 Integrated (0-6ft)

M1 - Deep Hole 043086 46.524860 -91.369280 Integrated (0-6 ft)/Van Dorn (hypolimnetic)M2 10048191 46.531780 -91.364705 Integrated (0-6 ft)M3 10048192 46.537773 -91.362689 Integrated (0-6 ft)H1 10048189 46.525914 -91.357931 Integrated (0-6 ft)

H2 - Deep Hole 043079 46.520260 -91.361273 Integrated (0-6 ft)/Van Dorn (hypolimnetic)H3 10048190 46.513894 -91.366001 Integrated (0-6 ft)T1 10048193 46.50925 -91.35913 Integrated (0-6ft)

T2 - Deep Hole 043127 46.50762 -91.36464 Integrated (0-6 ft)/Van Dorn (hypolimnetic)T3 10048395 46.50152 -91.37332 Integrated (0-6ft)

Eagle E1 - Deep Hole 043077 46.49830 -91.35919 Integrated (0-6 ft)Flynn F1 - Deep Hole 043078 46.49097 -91.34868 Integrated (0-6 ft)

Hart

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.815 Prosper Road

De Pere, WI 54115920.338.8860

www.onterra-eco.com

2,000

Feet

2017 Final HerbicideTreatment Strategy


Sources:Roads and Hydro: WDNRBathymetry: Onterra, 2016Map Date: May 26, 2017Filename: BuskeyBay_T2017_EWM_Prelim1.mxd

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Public Access"p

Bayfield County, Wisconsin

Buskey Bay

2017 Final EWMTreatment Area

Lake Millicent

Hart Lake

Twin Bear Lake

Eagle Lake

Flynn Lake

Lake Site AcresAve

DepthTotal

Volume 2,4-D

PPM ae*2,4-D

(gallons)*A-17 2.4 6.8 16.4 3.2 37B-17 11.7 9.8 115.1 3.2 263C-17 1.4 9.4 13.6 3.2 31D-17 3.4 8.5 28.8 3.2 66E-17 4.4 9.4 41.3 3.2 95F-17 1.7 10.5 17.5 3.2 40G-17 6.2 9.8 60.7 3.2 139H-17 1.8 10 17.9 3.2 41

Sub Total 33.0 311.3 712

I-17 1.2 7.5 9.2 3.9 26J-17 28.7 7.6 217.9 3.9 608K-17 2.1 6.8 14.5 3.9 41L-17 2.5 8.3 20.6 3.9 57M-17 0.9 13.9 11.9 3.9 33N-17 6.2 8.1 50.1 3.9 140

Sub Total 41.5 324.1 905

O-17 1.4 6.7 9.4 2.4 16P-17 4.1 8.3 34.0 2.4 58Q-17 2.7 8.5 23.0 2.4 39R-17 7.1 9.6 68.2 2.4 117

Sub Total 15.3 134.5 230

S-17 2.8 6.8 19.4 3.9 54T-17 1.3 10.4 13.2 3.9 37U-17 16.4 7.2 117.8 3.9 329V-17 6.3 8.7 54.5 3.9 152

Sub Total 26.7 204.8 572Grand Total 116.6 2419

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.Roads & Hydro: WDNRAquatic Plants: Onterra, 2016Map Date: July 13, 2017

Sources:

File Name: Eagle_T2017_EWM_DASH_Perm.mxd

600

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Extent of large map shown in red.

k


Bayfield County, WisconsinEagle & Flynn Lakes

July 2017 EWMSurvey Results &

Final EWM DASH Areas

Map 3

815 Propser RoadDe Pere, WI 54115

920.338.8860www.onterra-eco.com

LegendHighly ScatteredScatteredDominantHighly DominantSurface Matting


Clump of Plants!(

Single or Few Plants!(

2017 Final DASH Area

SiteFinal Acres

Ave Depth(feet)

A-17 2.2 7.0B-17 0.7 6.0C-17 0.4 6.0D-17 0.4 5.0E-17 0.2 6.0Total 3.9

2017 Final Control StrategyProfessional DASH Control

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A-17

B-17

E-17

C-17D-17

.Roads & Hydro: WDNRAquatic Plants: Onterra, 2016Map Date: July 13, 2017

Sources:

File Name: Eagle_T2017_EWM_DASH_Perm.mxd

600

Feet

Extent of large map shown in red.

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Bayfield County, WisconsinEagle & Flynn LakesAugust 2017 EWM

Survey Results

Map 4

815 Propser RoadDe Pere, WI 54115


LegendHighly ScatteredScatteredDominantHighly DominantSurface Matting


Clump of Plants!(


2017 Final DASH Area

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A-18

.815 Prosper Road

De Pere, WI 54115920.338.8860

www.onterra-eco.com

500

Feet

2017 EWM SurveyResults & Preliminary 2018 Treatment Areas

Pike Chain of LakesMap 5

Sources:Roads and Hydro: WDNRAquatic Plants: Onterra, 2017Bathymetry: Onterra, 2016Map Date: March 29, 2018 - TWHFilename: BuskeyBay_T2018_EWM_Prelim1.mxd

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Bayfield County, WisconsinBuskey Bay

Legend


ScatteredDominant (none found)Highly Dominant (none found)Surface Matting (none found)

Highly Scattered (none found)

2018 PreliminaryTreatment Area


Clump of Plants!(

SiteProposed

AcresAverage Depth

(feet)Volume

(acre-feet)Aquastrike

(gallon/acre-ft)Diquat


A-18 2.00 9.0 18.0 1.5 0.33 1.66

2018 Proposed EWM Treatment AreasAquastrike - (Diquat + endothall)

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B-18

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Map Date: April 11, 2018 - TWH

530

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Filename: PkChn_TwinBear_T2018_Prelim1 Project Location in Wisconsin

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815 Prosper RoadDe Pere, WI 54115


Sources:Roads and Hydro: WDNRAquatic Plants: Onterra, 2017Bathymetry: Onterra, 2016

2017 EWM SurveyResults & Preliminary2018 Treatment Areas



ScatteredDominant (none found)Highly Dominant (none found)Surface Matting (none found)

Highly Scattered (none found)

2018 PreliminaryTreatment Area


Clump of Plants!( Bayfield County, WisconsinTwin Bear LakeMap 6

SiteProposed

AcresAverage Depth

(feet)Volume

(acre-feet)Aquastrike

(gallon/acre-ft)Diquat


B-18 2.00 10.0 20.0 1.5 0.33 1.66

2018 Proposed EWM Treatment AreasAquastrike - (Diquat + endothall)

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