silverwaushara hwm managementreport2019 final

Silver Lake 2019 HWM Monitoring and Management District Control Strategy Development Report

January 2020 1

1.0 INTRODUCTION

[Big] Silver Lake, Waushara County, is a seepage lake with a maximum depth of 48 feet and a mean depth of 21 feet (Photo 1.0-1). The lake area as determined through a heads-up digitization of the lake from a 2015 aerial photograph is approximately 360.3 acres, whereas the WDNR website lists the lake as 328 acres. This mesotrophic lake has a relatively small watershed when compared to the size of the lake (3.5:1). Four exotic species are known to exist in Silver Lake: banded mystery snail, curly-leaf pondweed (Potamogeton crispus, CLP), Eurasian water milfoil (Myriophyllum spicatum, EWM), and zebra mussel. Genetic analysis confirms that the invasive milfoil population is comprised of both EWM and hybrid water milfoil (M. spicatum x sibiricum, HWM). Subsequent discussion using “HWM” will represent the collective invasive milfoil population of Silver Lake unless specifically referenced otherwise. Water levels in 2019 were at some of the highest levels ever recorded in the lake and resulted in the continued enforcement of a slow-no-wake ordinance that was initially put in place in September 2018 to limit shoreland erosion that could be exacerbated by waves created by boaters. The Silver Lake Management District (SLMD) is the local citizen-based organization leading the management of Silver Lake. The group has worked for years to protect and enhance the lake, including an increased effort in recent years to control HWM within the lake. The 2014 Aquatic Plant Management Plan recommended the SLMD initiate a large-scale (aka whole-lake) herbicide treatment targeting HWM in Silver Lake. A whole-lake granular triclopyr (Renovate OTF®) treatment occurred in early-June 2014 targeting 180-200 ppb acid equivalent (ae) lake-wide. Triclopyr concentrations fell short of achieving target levels in the main basin of the lake, but were found at higher concentrations in Foxtail Bay. The point-intercept data indicate that HWM was reduced lake-wide from 33.5% in 2013 (year before treatment) to 7.8% in 2014 (year of treatment); a 76.7% decline. SLMD members suspect that if the point-intercept survey would have occurred a month or two later in 2014, the HWM frequency of occurrence would have been higher as HWM was in the process of rebounding during the late-August survey. It is clear from 20.0% frequency recorded in the 2015 point-intercept survey (year after treatment) that the 2014 treatment resulted in only seasonal HWM control, likely greatly injuring HWM during the year of treatment but the population was in the process of recovering during 2015. Native plant impacts were relatively limited from the 2014 whole-lake triclopyr treatment. 1.1 2016 Fluridone Treatment Summary

The SLMD contracted with Onterra, LLC during May 2015 to provide technical direction as they pursued their goal to implement a large-scale herbicide treatment strategy during spring of 2016. Onterra developed a preliminary three-year control and monitoring strategy in which a large-scale herbicide treatment would occur in year two of the project.

Photo 1.0-1. Silver Lake, Waushara County, Wisconsin. Photo by Onterra 5-31-19.


January 2020 2

Following alternatives analysis, the SLMD decided to move forward with a pelletized fluridone treatment to target HWM in Silver Lake in 2016. Fluridone is a systematic herbicide that disrupts photosynthetic pathways (carotenoid synthesis inhibitor). This herbicide requires long exposure times (>90 days) to cause mortality to watermilfoils. In Wisconsin, a four-lake pilot project was conducted in the late-1990s and early-2000s. Liquid fluridone treatments within this study had peak fluridone concentrations of 12.4-15.9 ppb on three of the lakes, whereas the fourth had a peak concentration of 5.7 ppb. These treatments provided reduced EWM populations for up to four years, but resulted in native plant impacts that exceeded “acceptable levels” (Wagner et al. 2007). A revised use-pattern for fluridone was adopted on other midwestern lakes, particularly in Michigan, that initially targeted 6 ppb with a bump treatment later in the summer to bring the concentration back up to 6 ppb (6-bump-6) based upon the results of in situ herbicide concentration monitoring. These use-patterns produces relatively high herbicide pulses that taper off slowly as the herbicide degrades. Manufacturers of fluridone (SePRO) believe that the high herbicide pulses are the mechanism causing the native plant impacts. (Dr. Mark Heilman, personal comm.). A newer use-pattern of fluridone uses a pelletized product that gradually reaches a peak concentration over time (extended release) and results in a lower, sustained lake-wide herbicide concentration. For many of these initial treatments, the target concentration (4 ppb) was based upon theoretical equilibrium when mixed with the entire epilimnion. Because of the extended release rate and herbicide degradation, the 4-ppb initial target is not expected to be achieved, rather a prolonged period of 1.5 to 2.5 ppb is observed. Within a few limited Wisconsin field-trials, this use-pattern of fluridone appears to provide a similar level of efficacy as the 6-bump-6 approach, but with a lower magnitude (but still notable) of native plant impacts (Heath et al. 2018a, Heath et al. 2018b). The 2016 treatment included application of pelletized fluridone over 86.4 acres of the littoral zone known to contain HWM based on the 2015 Late-Season HWM Peak-Biomass Mapping Survey. The initial herbicide treatment was conducted by Clean Lakes on May 26, 2016. Based upon reviewing the measured herbicide concentration during the summer as well as technical advice from SePRO, 2 ppb bump treatments of pelletized fluridone (Sonar One®) were conducted on July 21 and September 1. The final dosing of these treatments was based on a mixing zone down to 21 feet and includes application of pelletized fluridone over the same 86.4 acres where the initial application occurred. The measured fluridone concentrations in the time period during and after the treatments are displayed on Figure 1.1-1. Note that fluridone concentrations persisted at a consistent level during the winter months and were detectable as late as July 2017. More specific details related to the 2016 fluridone treatment have been reported on in recent annual reports as a part of this project.


January 2020 3

1.2 Integrated Pest Management (2017- Current)

Many lake groups initiate a large-scale herbicide strategy with the intention of implementing smaller-scale control measures (e.g. herbicide spot treatments, hand-removal) when HWM begins rebounding. This is referred to as Integrated Pest Management (IPM) and the approach has shown promise on many lakes. However, the HWM population rebounds on many lakes in a lake-wide fashion that may not always lend well to implementing IPM. Following discussions with the SLMD, a professional hand-harvesting strategy was devised for 2017 such that divers would remove the HWM located during the June 2017 ESAIS survey and then conduct scuba reconnaissance surveys at various locations around the lake where dense colonies of HWM had been mapped during the 2015 growing season. Six subsequent days of scuba reconnaissance allowed the professional hand-harvesting firm to visit all 36-designated search areas, spending a total of 38.95 hours underwater. Divers encountered varying amounts of milfoil, which was presumably all EWM/HWM but difficult identification at this growth stage is noted. The hand-harvesting firm indicated the plants that they removed were typically small single-stalked plants that did not appear to be growing out of a large root crown. It is unclear if this represents plants that survived the treatment or was a result of germination from a seedbank or sprouting from asexual turions (i.e. winter buds). Surveys conducted in 2017 on Silver Lake show that 2016 fluridone treatments met the control objectives. Professional hand-harvesting efforts in 2017 likely aided in maintaining the HWM population at a relatively low level. The native plant community exhibited some reduction in 2017, likely from a combination of the large scale fluridone treatment and environmental factors from the large amounts of precipitation and corresponding increase in water levels.

Figure 1.1-1. Fluridone concentrations measured in Silver Lake in association with a 2016 whole-lake treatment.


January 2020 4

The SLMD continued with an IPM HWM management strategy in 2018 that utilized an increased amount of professional DASH efforts. The professional DASH efforts in 2018 were able to effectively maintain or reduce the HWM population in all of the sites in which efforts were undertaken with the exception of Foxtail Bay. Following this management strategy, professional hand-harvesting as well as a spot herbicide treatment were proposed to manage HWM in 2019. A preliminary strategy of ProcellaCOR™ herbicide treatment in Foxtail Bay for 2019 was presented to local WDNR biologists in mid-January 2019. Ultimately, the herbicide treatment strategy was postponed due to concerns of limited quantitative pretreatment data, low abundance of target plants in that area, and a newer herbicide requiring additional WDNR technical review. The Lake District contracted with a professional hand-harvesting firm (Aquatic Plant Management, LLC) to implement DASH services in 2019. The SLMD made a large commitment to DASH in 2019 with up to eight weeks of DASH harvesting efforts. This included a dedicated week of effort specifically targeting Foxtail Bay during 2019, which ultimately became three weeks of DASH. The District believed that greater HWM population management strides in this bay may be achieved by implementing the strategy earlier in the growing season (early June) when HWM and native plants are at an earlier growth stage. The extended use of DASH was intended to help delay the need for herbicide control strategies in the future. The SLMD strides to be on the leading frontier of HWM management in Wisconsin through implementing best management practices to meet the desired level of HWM control. The extensive DASH efforts in 2017-2019 will be instrumental in furthering the science behind the understanding of the role that this management technique may have in Silver Lake and other Wisconsin lakes. A pair of HWM mapping surveys were used within this project to coordinate and qualitatively monitor the hand-harvesting efforts (Figure 1.2-1). The first monitoring event on Silver Lake in 2019 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-treatment assessment of the hand-harvesting.

Figure 1.2-1. Hand-Harvesting Strategy Timeline.


January 2020 5

2.0 2019 AQUATIC PLANT MONITORING RESULTS

2.1 Early-Season AIS Survey (ESAIS) (Pre-Hand-Harvesting)

Onterra field crews completed the ESAIS survey on Silver Lake on May 31, 2019. Crews noted excellent weather conditions during the survey with sunny skies and light winds. During the survey, the entire littoral area of the lake was surveyed through visual observations from the boat and the HWM population was mapped. Crews noted that the HWM was tall and green and visible from the surface. The HWM population was mapped using sub-meter GPS technology by 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 < Scattered < Dominant < Highly Dominant < Surface Matting. Point-based techniques were applied to AIS locations that were considered as Small Plant Colonies (<40 feet in diameter), Clumps of Plants, or Single or Few Plants. The HWM population mapped during the ESAIS survey are displayed on Map 1. Highly scattered, scattered, and highly dominant colonies were located within Foxtail Bay along with numerous singles, clumps of plants and small plant colonies. In the main body of the lake, one scattered colony of HWM was located along the southern shoreline of the lake, whereas all other occurrences in the lake were mapped with point-based methodologies as singles, clumps or small plant colonies. From this survey, a final hand-harvesting strategy was developed that included six priority harvesting sites as well as 35 additional dive sites (see table embedded on Map 1). The six priority harvesting sites were further prioritized by the SLMD. The 35 dive sites were a combination of sites that were carried over from the sites that were developed as a part of the 2017 hand-harvesting/dive reconnaissance program or moved in areas where lower density HWM was located during the 2019 ESAIS survey. It was recommended that professional harvesting efforts focus on the highest priority sites first before moving onto other sites. Onterra provided the spatial data reflecting the ESAIS results to the professional harvesting firm in the form of a GPS compatible basemap to aid in the removal efforts. 2.2 Professional Hand-Harvesting Actions

The SLMD contracted with Aquatic Plant Management, LLC in 2019 to provide professional DASH services. The SLMD contracted for 40 days of professional hand harvesting services in 2019 totaling 320 total hours and at a cost that exceeded $100,000. The 320 total contracted hours resulted in 212.81 hours of underwater diving time. AIS removal specialists from APM completed DASH services that totaled 92.95 hours of underwater dive time in June, 56.68 hours in July, and 63.18 hours in August. A summary of the DASH efforts by harvest site is displayed on Table 2.2-1. During the course of the removal efforts, a total of 1,246 cubic feet of HWM was harvested from the permitted areas. The greatest amount of DASH effort took place in Foxtail Bay

Table 2.2-1. Silver Lake, 2019 professional hand-harvesting activities.

Site Acres

Priority

(SLMD)

Time

(hours)

Harvest

(cubic feet)

A‐19 0.93 1 20.91 46.0

B‐19 0.16 3 8.41 12.0

C‐19 0.26 5 5.00 7.0

D‐19 0.26 2 6.17 9.5

E‐19 0.31 4 4.84 8.0

Fox Tail Bay 10.30 1 121.63 1075.0

Subtotal 12.22 166.96 1157.5

All 35 Dive Sites

(1/3 acre each)11.67 Last 45.85 88.5

Total 23.89 212.81 1246.5

2019 Professional Hand‐Harvest

EWM Control StrategyDASH Summary


January 2020 6

where 121.63 hours of dive time yielded a harvest of 1,075 cubic feet of HWM. Additional details related to the professional harvesting actions are included in a summary dive report created by APM, LLC as an appendix to this report. 2.3 Late-Summer HWM Peak-biomass Survey (Post Hand-Harvesting)

The HWM population was mapped on September 26, 2019, approximately six weeks following the completion of the hand-harvesting efforts. During the survey, Onterra field crews meandered the littoral zone of the lake and mapped HWM populations using sub-meter GPS technology. Conditions were favorable during the survey with sunny skies and light winds. The results of the late-summer HWM mapping survey are displayed on Map 2. The largest concentration of HWM was found in Foxtail Bay where approximately 6.75 acres of colonized plants were mapped. The densest area of HWM in the bay was a highly dominant colony found in the northern end of the bay in water approximately 5’ or less. A dominant colony of HWM that was approximately two acres in size was delineated in the middle of Foxtail Bay. Additional areas of highly scattered and scattered density colonized areas were mapped within the bay. Some of the lowest HWM populations in the Bay were located along the eastern side of the Bay in shallower waters which corresponds to areas where DASH removal efforts were more effective. Outside of Foxtail Bay, the HWM in the main body of the lake saw a modest increase in the population with a few relatively small colonized areas as well as numerous low-density occurrences that consisted of singles, clumps of plants, or small plant colonies. The majority of the HWM that was located during Onterra’s late-summer survey were outside of the designated 2019 DASH work areas. Professional Hand-Harvesting Site Assessments

The sites that were targeted for professional harvesting are highlighted in Figures 2.3-1 through 2.3-3 where the left frame shows the pre-harvesting HWM population mapped in early summer 2019 and the right frame show the post-harvesting HWM population mapped in late-summer 2019. It should be noted that the late-summer mapping survey was completed approximately six weeks following the completion of the DASH efforts. This allows for sufficient time for HWM rebound in these areas from root crowns that were not completely removed. Site A-19: This area was also targeted in 2018 with professional harvesting actions that resulted in the harvest of 181.5 cubic feet of HWM over 14.29 hours of dive time. The 2019 ESAIS survey indicated the HWM population increased since 2018 with a scattered colony of HWM present in the site. Professional DASH efforts in 2019 totaled 20.91 hours of dive time in the summer and a total harvest of 46 cubic feet of HWM was reported. The late-summer mapping survey showed a decrease in the HWM population with two small plant colonies and one single or few plants occurrence remaining in the site. Site B-19: The 2019 ESAIS survey showed three clumps of HWM present in site B-19. Professional removal efforts totaled 8.41 hours of dive time and resulted in the harvest of 12 cubic feet of HWM. The late-summer survey showed the HWM population was reduced in the site with one single or few plants occurrence located on the west end of the site. Site C-19: The 2019 ESAIS survey indicated a highly dominant colony was present in site C-19. Professional DASH removal efforts totaled five hours of dive time with seven cubic feet of reported


January 2020 7

HWM harvest. The late-summer HWM mapping survey indicated a reduction of HWM in the site with only a clump of plants and a number of single or few plant occurrences remaining. Site D-19: The 2019 ESAIS survey indicated numerous single or few HWM plants present in site D-19. Professional DASH removal efforts totaled 6.17 hours and resulted in 9.5 cubic feet of HWM harvest. The late-summer HWM mapping survey showed the HWM population remained low in the site with a clump of plants and several single or few plant occurrences remaining in the site. Site E-19: The 2019 ESIAS survey indicated a small plant colony and clump of plants were present in the site. Professional DASH removal efforts totaled 4.84 hours and resulted in the harvest of eight cubic feet of HWM. No HWM was located in the site during the late-summer HWM mapping survey. Foxtail Bay: The largest known population of HWM in the lake was located in Foxtail Bay and included a few large, contiguous colonies of highly scattered, scattered, and highly dominant densities. Professional DASH efforts totaled 121.63 hours and yielded 1,075 cubic feet of HWM harvest. The late-summer survey indicated that the HWM population expanded over the growing season such that large and comparatively more dense colonies of HWM were present. Other Dive Sites/Reconnaissance Sites: A total of 35 sites, 1/3 acre in size, were included on the 2019 DASH strategy as Dive Sites or Reconnaissance Sites. These sites either held very dense populations of HWM prior to the large scale fluridone treatment, or they were known to contain modest HWM populations as indicated by the late-May 2019 ESAIS survey. Professional DASH efforts totaled 45.85 hours between the dive sites and resulted in a harvest of 88.5 cubic feet of HWH. The late-summer 2019 HWM mapping survey indicated little or no HWM present at the majority of the dive sites, however HWM was present within, or immediately adjacent to, some of the sites.


January 2020 8

Late-May 2019 (Pre Hand-Harvesting)

Dive Time: 20.91 Hours

Harvest Total:

46 cubic feet


Harvest Total:

12 cubic feet

September 2019 (Post Hand Harvesting)

Figure 2.3-1. HWM Populations from before (Late-May 2019) and after (September 2019) Professional Hand-Harvesting Efforts at sites A-19 & B-19 in Silver Lake.

!(!(

!(

!(

!(!(

!(

Legend

Small Plant Colony!(

Clump of Plants!(

Single or Few Plants!(

Surface Matting

Highly Dominant

Dominant

Scattered

Highly Scattered

2019 PriorityHand-Harvest Site

D-19

E-19

C-19

B-19

A-19

A-19

A-19

B-19

B-19


January 2020 9


Dive Time: 5 Hours

Harvest Total:

7 cubic feet


Harvest Total:

9.5 cubic feet


Figure 2.3-2. HWM Populations from before (Late-May 2019) and after (September 2019) Professional Hand-Harvesting Efforts at sites C-19 & D-19 in Silver Lake.

!(

!(

!(

!(!(!(

!(!(

!(

!(

!(

!(

!(

!(

!(

!( !(

!(

Legend


Clump of Plants!(


Surface Matting

Highly Dominant

Dominant

Scattered

Highly Scattered


D-19

E-19

C-19

B-19

A-19

C-19

C-19

D-19

D-19


January 2020 10



Harvest Total:

8 cubic feet


Harvest Total:

1,075 cubic feet


Figure 2.3-3. HWM Populations from before (Late-May 2019) and after (September 2019) Professional Hand-Harvesting Efforts at sites E-19 & Foxtail Bay in Silver Lake.

!(

!(!(

!(!( !(

!(!(

!(

!(!(

!(!( !(!(

!(!(

!(

!(

!(!(!(

!(!(!(!(

!(

!(!(

!(!(!(!(!(

!(

!(

!(!(!(!(

!(!(!(!(

!(!( !(

!(!(!(!(!(!(

!(!(!(!(!(!(!(!( !(!(!(!(

!(!(

!(!(!(!(!(!(!(

!(!(!(!(!(!(!(!(!(!(

!(!(!(!(!(!(!(!(

!(!(!(

!(!(!(!(!(!(!(!( !(

!(!(

!(!(!(!(!(!(!(

!(

!(

!(!(!(!(!(

!(!( !(!(

!(

!(

!(!(!(!(

!(

!(!(

!(!(!( !(

!(!(

!(!(!(!(

!(!(

!(!( !(!(

!(!(

!(

!(!(!(!(

!(

!(!(

!(

!(

!(

!(

!(

!(

!(!(!(!(!(

!(

!(

Legend


Clump of Plants!(


Surface Matting

Highly Dominant

Dominant

Scattered

Highly Scattered


D-19

E-19

C-19

B-19

A-19

E-19

E-19

Foxtail

Foxtail


January 2020 11

2.4 2019 Point-Intercept Survey Results

Point intercept surveys have been conducted on Silver Lake every year since 2012, with the exception of 2016, with the purpose of quantitatively monitoring the aquatic plant population during a period of active HWM management. The survey was replicated in 2019 to allow for further understanding of the native and non-native plant populations three-years after the last large-scale herbicide treatment that took place in 2016. Figure 2.4-1 displays the littoral frequency of occurrence of HWM in Silver Lake from 2012-2019. Following the 2016 fluridone treatment, the data show that the littoral frequency of HWM was initially as low as 0.2% in 2017 and has increased incrementally since with a 1.7% occurrence in 2018 and 2.3% occurrence in 2019. The 2019 occurrence of 2.3% is not statistically different than the 2018 occurrence of 1.7%. The 2019 survey indicates the HWM population is currently 89% lower than before the treatment.

Along with understanding the level of HWM control achieved from the control action, the point-intercept data also allows for an understanding of non-target native plant impacts from the treatment. Figure 2.4-2 displays the average number of native aquatic plant species at each sampling site from point-intercept surveys conducted between 2012 – 2019. The average number of native species varied between 1.65 and 1.82 from 2012-2015 before declining to under 1.0 in 2017 following the whole-lake fluridone treatment. The number of native species per site increased between 2017-2018 potentially as some species recovered from the treatment. The 2019 survey found the number of native species per site decreased since 2018 to 1.24. It is suspected that environmental factors, particularly the increased water levels in 2019, likely influenced the native plant populations in Silver Lake to a greater degree than the relatively selective process of the professional HWM hand harvesting strategy. Ten native species initially exhibited a statistically valid decrease in occurrence following the fluridone treatment as determined by comparing the 2015 (pre-treatment) survey to the 2017 (post treatment). The frequency of occurrence of common waterweed (Elodea canadensis, -100%) and coontail (Ceratophyllum demersum, -44.3%) represents a statistically valid decrease from 2015 to 2017 (Figure

Figure 2.4-1. Littoral frequency of occurrence of HWM in Silver Lake. Open circle represents statistically valid change from previous survey (Chi-Square α = 0.05).

Figure 2.4-2. Average number of native species per sampling site from point-intercept surveys conducted from 2012-2019 on Silver Lake.

Large‐scaleFluridone

Large‐scaleTriclopyr

25.3

33.3

7.8

20.0

0.2 1.7 2.3

0

10

20

30

40

50

60

70

80

90

100

Litto

ral F

requ

ency

of

Occ

urre

nce

(%)

2012 2013 2014 2015 2016 2017 2018 2019Large‐scale Fluridone

Large‐scale Triclopyr

1.821.65

1.821.65

0.95

1.461.24

0

1

2

3

4

Ave

rag

e N

um

be

r o

f Na

tive

Sp

eci

es

pe

r si

te(<

max

dep

th o

f pl

ants

)

2012 2013 2014 2015 2016 2017 2018 2019


January 2020 12

2.4-3). According to a fluridone susceptibility analysis completed by the WDNR Science Service Department, common waterweed and coontail were shown to be particularly sensitive to fluridone treatments. A relatively robust population of coontail remained present in the lake during the 2017 point-intercept survey in which coontail was the second most common species with a frequency of 20.2%. The population of coontail has been relatively stable between 2017-2019 and with a 21.9% occurrence in the 2019 survey, was the most frequently encountered species in the lake. The population of common waterweed has been slow to recover after the fluridone treatment with the 2018 survey indicating a 1.3% littoral frequency of occurrence and the 2019 survey indicating a 2.3% occurrence.

Coontail (Ceratophyllum demersum) Common waterweed (Elodea canadensis)

Figure 2.4-3. Littoral frequency of occurrence of coontail (Ceratophyllum demersum) and common waterweed (Elodea canadensis) from 2012-2019 in Silver Lake. Data from 2012-2019 point-intercept surveys. Open circle represents statistically valid change from previous survey (Chi-Square α = 0.05). 2013 large-scale triclopyr treatment and 2016 large-scale fluridone treatment indicated by red dashed lines. Other native species that exhibited a statistically valid decrease in littoral frequency of occurrence following the fluridone treatment are displayed on Figure 2.4-4. In recent years, the occurrences of several native species such as variable-leaf pondweed, Fries’ pondweed, and white-stem pondweed, have recovered to approximately the pre-treatment levels. The littoral occurrences for Illinois pondweed and southern naiad remain somewhat below pre-treatment levels three year after treatment. A chi square analysis for all available point-intercept survey results from 2012 to 2019 is included with this report as an appendix.

Large‐scale Fluridone


32.9 32.9

42.5

36.3

20.225.5

21.9

0

10

20

30

40

50

60

70

80

90

100

Litto

ral F

requ

ency

of

Occ

urre

nce

(%)

2012 2013 2014 2015 2016 2017 2018 2019



27.8

35.1

28.2

19.1

0.0 1.3 2.3

0

10

20

30

40

50

60

70

80

90

100

Litto

ral F

requ

ency

of

Occ

urre

nce

(%)

2012 2013 2014 2015 2016 2017 2018 2019


January 2020 13

Variable-leaf pondweed (Potamogeton gramineus) Illinois pondweed (Potamogeton illinoensis)

Fries’ Pondweed (Potamogeton friesii) White-stem Pondweed (Potamogeton praelongus)

Muskgrasses (Chara sp.) & Stoneworts (Nitella sp.) Naiads (Najas flexilis & N. guadalupensis)

Figure 2.4-4. Littoral frequency of occurrence from of native aquatic plant species that exhibited a statically valid decrease in occurrence following the large-scale fluridone treatment in Silver Lake. Data from 2012-2018 point-intercept surveys. Open circle represents statistically valid change from previous survey (Chi-Square α = 0.05). 2013 large-scale triclopyr treatment and 2016 large-scale fluridone treatment indicated by red dashed lines.



20.7

13.610.7 11.1

3.5

15.110.7

0

10

20

30

40

50

60

70

80

90

100

Litto

ral F

requ

ency

of

Occ

urre

nce

(%)

2012 2013 2014 2015 2016 2017 2018 2019



4.6 2.7 4.7 5.41.5 0.6 1.5

0

10

20

30

40

50

60

70

80

90

100

Litto

ral F

requ

ency

of

Occ

urre

nce

(%)

2012 2013 2014 2015 2016 2017 2018 2019



2.1 3.4 2.2

11.7

4.6 3.98.2

0

10

20

30

40

50

60

70

80

90

100

Litto

ral F

requ

ency

of

Occ

urre

nce

(%)

2012 2013 2014 2015 2016 2017 2018 2019Large‐scale Fluridone


4.6 4.08.5

4.81.5

4.1 4.2

0

10

20

30

40

50

60

70

80

90

100

Litto

ral F

requ

ency

of

Occ

urre

nce

(%)

2012 2013 2014 2015 2016 2017 2018 2019



33.8

25.130.0 23.9

25.7

33.5

23.6

0

10

20

30

40

50

60

70

80

90

100

Litto

ral F

requ

ency

of

Occ

urre

nce

(%)

Muskgrasses &

Stoneworts

Stoneworts

Muskgrasses

2012 2013 2014 2015 2016 2017 2018 2019



24.721.3 22.6

16.5

3.7

9.77.0

3.2 1.8 3.8 3.0

0.03.2

3.00

10

20

30

40

50

60

70

80

90

100

Litto

ral F

requ

ency

of

Occ

urre

nce

(%)

Southern naiad

Slender naiad

2012 2013 2014 2015 2016 2017 2018 2019


January 2020 14

3.0 CONCLUSIONS AND DISCUSSION

The Lake District has invested a great deal of resources over the past two years in an effort to manage the HWM population at a lowered level with a professional hand harvesting control strategy that largely utilized diver assisted suction harvesting. Increasing amounts of hand harvesting efforts have taken place each year from 2017-2019 (Table 3.0-1). The 2019 DASH efforts met or exceeded lake managers expectation in each of the five priority sites. Overall, the hand-harvesting efforts were effective at managing the HWM populations in most areas where is was applied, however some HWM population increases were observed in areas of the lake that were outside of the targeted areas. Managing the HWM population in Foxtail Bay has proven difficult with a hand-harvesting technique and the rate of HWM population expansion in the site remains too great for this management technique to be effective in maintaining or reducing the population in this location. The overall HWM population continues to be at a much lower level than was observed prior to the large-scale fluridone treatment.

Table 3.0-1. Silver Lake, 2017-2019 Integrated Pest Management Activities: Professional DASH

There has been an interest in defining success criteria in association with the hand harvesting HWM control strategy in Silver Lake. Success criteria need to be flexible to allow for modifications over time as the HWM population changes and a greater understanding of the capabilities of this technique evolve through experience. Hand-removal programs for HWM are relatively new and measuring the success of hand-harvesting activities, particularly with low-density HWM occurrences, can be complex and requires revision as the project progresses. Some level of HWM population tolerance is necessary as eradication is not a feasible outcome when managing HWM in Silver Lake. Based on conversations between the SLMD, Aquatic Plant Management, LLC, and Onterra, a working success criterion for 2020 is emerging. Defining control expectations for the hand harvesting program for 2020 would be done in two ways: a site-by-site basis as well as on a lake-wide basis.

Site-by-Site Success Criteria: The 2020 DASH strategy would be evaluated on a site-by-site basis by comparing the pre-harvesting population mapped during the late-summer 2019 survey to the late-summer 2020 post-harvesting survey. This evaluation would be specific to the priority areas that were included on the 2020 DASH permit.

1) Sites that contained colonized HWM in late-summer 2019 would meet success criteria if the post-harvesting survey indicates that no colonized areas of HWM were present in the site and any remaining HWM in the site could be mapped using point-based mapping methods (i.e. singles, clumps, or small plant colonies).

2) The 2020 priority sites that contained small plant colonies or clumps of plants in the late-summer 2019 survey would meet control expectations by exhibiting a decrease in the HWM population as demonstrated by a reduction in the size or number of HWM small plant colonies or clumps of plants occurrences present in the site between the 2019 and 2020 late-summer surveys.

YearHours

Underwater HWM Harvest

2017 38.95 1,300+ plants

2018 78.49 621.3 ft3

2019 212.81 1246.5 ft3


January 2020 15

By applying these success criteria to the 2019 strategy, four sites would have met the success criteria and two sites would fall short (Table 3.0-2). The Foxtail Bay site would not have met success criteria because colonized HWM present in the May survey was not reduced to point-based occurrences. By adopting these criteria, site D-19 falls short of meeting the success criteria because a clump of plants occurrence was located in the site where previously, the population was represented by smaller point-based occurrences consisting of single or few plants.

Table 3.0-2. Success Criteria Evaluation of 2019 Priority DASH sites.

Lake-wide Success Criteria: The goal of the 2020 DASH strategy on a lake-wide scale is to manage the HWM population in the main body of the lake at relatively low levels such that there is likely to be minimal negative impacts to the riparian’s use of the lake for activities like boating or swimming. This excludes the HWM population in Foxtail Bay which is not a part of the hand harvesting strategy in 2020. A realistic outcome for this goal may be met by suppressing the lake-wide population such that no HWM colonies reach a size over one acre and a density of dominant or greater by the time of the September 2020 survey.

If the 2020 lake-wide success criteria described above were applied to the 2019 harvesting program, the success criteria were met since there were no colonies outside of Foxtail Bay that were over an acre in size by the time of the late-summer survey. As a part of an ongoing Integrated Pest Management (IPM) strategy following the 2016 large-scale treatment, the SLMD intends to continue to implement follow-up management actions that include hand-harvesting and/or herbicide spot treatments in an effort to maintain the HWM population at lower levels in Silver Lake. Following this management strategy, professional hand-harvesting as well as a spot herbicide treatment are discussed below. The SLMD will be submitting an application for a WDNR AIS-Established Population Control Grant to assist with funding the IPM strategy. 3.1 2020 IPM Strategy: Hand-Harvesting

In addition to the herbicide management strategy outlined below, the SLMD plans to continue to manage the lake-wide HWM population with a coordinated hand harvesting/DASH control strategy in 2020. It is believed the current HWM population in the main body of Silver Lake (outside of Foxtail Bay) is manageable with a coordinated DASH effort in 2020. The amount of effort required to manage the HWM population may be similar to 2019, however, no DASH efforts are planned to be directed at Foxtail Bay which will free up time to cover more locations in the main body of the lake. A DASH strategy that

Site May 2019 Pre Hand‐Harvest

September 2019 Post Hand‐

Harvest

Success

Criteria Met?

A‐19 PGs (Scattered) Pnts (SPC, S) Yes

B‐19 Pnts (SPC, S) Pnts (S) Yes

C‐19 PGs (Highly Dominant) Pnts (CL, S) Yes

D‐19 Pnts (S) Pnts (CL, S) No

E‐19 Pnts (SPC, CL) None Yes

SPC = Small Plant Colony, CL = Clumps of Plants, S = Single or Few Plants

Pnts= Only Point‐Based Mapping, PGs = Includes Polygon‐Based Mapping

PGs (Highly Scattered,

Scattered, Highly Dominant)

PGs (Highly Scattered, Scattered,

Dominant, Highly Dominant)Fox Tail Bay No


January 2020 16

targets all known HWM that is a clump of plants or greater includes 21 sites and totals approximately 16.8 acres with sizable buffers on each work area is displayed on Map 3. The 2020 DASH sites are further prioritized by either 1st, 2nd, or 3rd level priority based on the HWM population in the site. Sites with colonized HWM, mapped with polygons, were given first priority. Sites with at least a small plant colony were given second priority and sites with clumps of plants or less HWM were given third priority. Map 3 may be submitted to the WDNR to obtain the DASH permit for 2020. It is expected that the amount of DASH efforts required to meet the 2020 control expectations could be of a similar magnitude to 2019 during which 40 days of harvesting efforts took place. If the SLMD wishes to limit the amount of DASH efforts in 2020 to some lower level, then prioritization of efforts will be of greater importance. In the past two years, Onterra completed an Early Season HWM Mapping Survey before professional DASH efforts began. This allowed Onterra to find sufficient locations for the DASH efforts to be focused on and create prioritization. As the HWM population slowly rebounds, the utility of completing the survey at the beginning of the season diminishes as the prior years’ Late Season HWM Mapping Survey already provides sufficient guidance for the DASH efforts. For 2020, a modification to the timing of Onterra’s early season HWM mapping survey is planned. In 2020, DASH efforts would begin as soon as conditions are favorable based off of the permit developed from the Late-Summer 2019 HWM Mapping Survey results. Onterra would plan to conduct a mid-summer HWM mapping survey around mid to late-July unless prompted earlier based on the progression of the DASH efforts. The mid-summer survey will serve to locate any new HWM populations in the main body of the lake that were outside of the originally permitted DASH locations. The results of the survey will allow for a chance to adjust the prioritization strategy for the remaining hand harvesting efforts during the season, including making any modifications to the DASH permit. This will allow for ensuring the professional harvesting efforts are directed as efficiently as possible during the 2020 season. If the professional DASH teams have harvested the majority of the HWM from the permitted sites earlier in the summer, then Onterra would be notified and the mid-summer survey would be prompted to occur when it is needed. By altering the timing of the survey, it would present lake managers with an opportunity to evaluate whether additional DASH time is likely to meet the goals of the project or if it may be better to consider limiting or ceasing DASH efforts for the rest of the growing season based on the early results and an early look at the HWM population in the lake. Consistent with the recent monitoring strategy, a late-summer HWM mapping survey would occur after the completion of harvesting efforts and be used to evaluate the 2020 control activities as well as develop a preliminary strategy for 2021. The DASH control strategy would be evaluated based on the success criteria discussed above in Section 3.0.

3.2 2020 IPM Strategy: Herbicide Spot-Treatment

Foxtail Bay has contained some dense populations of HWM in recent years and was originally considered for herbicide control of HWM in 2019. Hand-harvesting in this area of Silver Lake in 2018 proved to be challenging as dense native aquatic plants hindered the professional diver’s removal efforts and resulted in falling short of meeting control expectations. Substantial DASH efforts in 2019 showed that this management technique has limits in its capabilities to reduce the HWM population in this site. It has become clear over the past two years that DASH alone cannot keep up with the rate of HWM expansion in Foxtail Bay.


January 2020 17

The protected nature of this bay of the lake is believed to aid in limiting herbicide dissipation out of the application area and is theorized to allow for sufficient concentration exposure times to result in HWM control. However, this area has a history of various herbicide treatments with mixed results. Because of the stage of recovery/rebound of the HWM population, the SLMD considered a potentially more aggressive management approach to this population. This included evaluation of several herbicide herbicides that require short exposure times (diquat, florpyrauxifen-benzyl [ProcellaCOR™]) and herbicide combinations (diquat/endothall, 2,4-D/endothall, etc.). At the time of this report, the Lake District intends to pursue a control strategy that utilizes florpyrauxifen-benzyl, commercially available as ProcellaCOR™ (SePRO). This herbicide is specifically designed to control invasive milfoil populations. ProcellaCOR™ is in a new class of synthetic auxin mimic herbicides (arylpicolinates) with short concentration and exposure time (CET) requirements compared to other systemic herbicides. Uptake rates of ProcellaCOR™ into EWM were two times greater than reported for triclopyr (Haug 2018, Vassios et al. 2017). ProcellaCOR™ is primarily degraded by photolysis (light exposure), with some microbial degradation. The herbicide is relatively short-lived in the environment, with half-lives of 4-6 days in aerobic environments and two days in anerobic environments (WSDE 2017). The product has a high affinity for binding to organic materials (i.e. high KOC). Netherland and Richardson (2016) and Richardson et al. (2016) indicated control of select non-native plant species with the active ingredient in ProcellaCOR™, including invasive watermilfoils (EWM and HWM) at low application rates compared with other registered spot treatment herbicides. The majority of native plants tested to date also suggest greater tolerance to this mode of action. Water lilies, pickerelweed, arrowheads, and native watermilfoils have shown sensitivity to ProcellaCOR™. Coontail may also be impacted at higher application rates. Because this is a new herbicide, data available from field trials is relatively limited. The use of any aquatic herbicide poses environmental risks to non-target plants and aquatic organisms. The EPA Ecological Risk Assessment places the risk to non-target wildlife into the “no risk concern” category and the impacts to bees, birds, reptiles, amphibians, and mammals in the “practically non-toxic” category. The EPA has also indicated that there are no known risks of concern to human health. There are no restrictions on swimming, drinking, fish consumption, or turf irrigation. However, there would be an approximate 1-day waiting period of the proposed application for shoreland irrigation due to concerns of herbicidal impacts. Additional information from the WDNR related to aquatic herbicide regulation and the WDNR’s Chemical fact sheet for florpyrauxifen-benzyl have been included in past reports and are also available online. The SLMD initiated a quantitative monitoring plan at an increased intensity during the summer of 2019 to serve as a pretreatment dataset for herbicide treatment during spring of 2020. An increased sampling intensity was developed for 2019 that used a 20-meter spacing for a sub point-intercept survey and resulted in 89 sampling locations (Figure 3.2-1). The littoral frequency of occurrence of aquatic plants from the sub point-intercept survey collected in September 2019 are displayed on Figure 3.2-1. The survey results showed white-stem pondweed (67.4%) and coontail (41.6%) were the most frequently encountered native species in the site with 13 additional native species present at lower frequencies. The littoral occurrence of HWM in the site was found to be 36%.


January 2020 18

A dosing strategy of 3.5 PDU’s/acre-ft for the 2020 treatment was determined with the technical assistance from SePRO and the preliminary treatment strategy is displayed on Map 4. The area of potential impact for the proposed treatment includes all of Foxtail Bay which includes the entire area that the sub point-intercept data was collected from. As was proposed for 2019, herbicide concentration monitoring would accompany the 2020 treatment, with a preliminary design investigating six time intervals (1, 3, 6, 12, 24, and 48 hours after treatment) at four locations. The final monitoring design will be determined based on discussions with the WDNR. It is encouraged that the herbicide application occurs during a period of low wind speeds to help minimize any wind driven herbicide dissipation out of the site. Onterra staff would complete a Pre-treatment Confirmation and Refinement survey before the proposed 2020 treatment. The purpose of the survey is to confirm the treatment area extents and average depths of the site as well as to confirm that the HWM is actively growing. At the time of the survey, Onterra would coordinate with volunteers from the SLMD to deliver the supplies and training necessary to carry out the post-treatment herbicide concentration monitoring.

Figure 3.2-1. Littoral frequency of occurrence of aquatic plants in Foxtail Bay from a September 2019 sub point-intercept survey. (n=89).

!(

!(!(!(!(!(!(

!(!(!(

!(!( !(

!(!(!(!(

!(!(!(!(!(

!(

!(!(!(

!(

!(

!(!(!(

!( !(

!( !(!(

!(!(

!(

!(!(

!(!(

!(

!(

!( !(!(!(!(!(!(!(!(

!(

!(!(

!(

!(

!(

!(!(

!(!(!(!(

!(!(

!(

!(

!(!(!(

!(!(!(!(

!(

!(!(

!(!(!(!(!( !(!(

!(!(!(!(

!(!(!(!(

!(!( !(!(!(!(

!(!(!(!(!(!(!(!(!(!(!( !(!(!(!(!( !(

!(!(!(!(!(!(!(!(!(!(!(!(!(!(!( !(!(

!(!(!(!(!(!(!(!(!(!(!(!(!(!(!(!(!(!(!( !(

!(!(

!(!(!(!(!(!(!(

!(!(

!(!(!(!(!(

!(!(!(!(!(

(

(

(

(

(

(

(

(

((

(

(

(

(

(

(

(

(

((

(

(

(

(

(

(

(

(

(

(

(

(

(

(

(

"p

"p

"p

"r

C-19

A-19

E-19

B-19

D-19

FoxTailBay-19

. Map 1

815 Prosper RoadDe Pere, WI 54115

920.338.8860www.onterra-eco.com

Sources:Roads and Hydro: WDNRBathymetry: Onterra, 2015Aquatic Plants: Onterra, 2018Map Date: June 5, 2019 TWH Project Location in Wisconsin

k

1,000

FeetLegend

May 2019 HWM/EWM LocationsHighly Scattered Single or Few Plants!(

Clump of Plants!(

Small Plant Colony!( 2019 Final Hand-Harvest Sites

Scattered Dominant

Waushara County, WisconsinSilver Lake


Dive Recon &DASH Removal Site(

Highly Dominant Surface Matting

Site Acres PriorityA-19 0.93 1stB-19 0.16 1stC-19 0.26 1stD-19 0.26 1stE-19 0.31 1st

Fox Tail Bay - 19 10.30 EarlySubtotal 12.22

All 35 Dive Sites(1/3 acre each) 11.67 2nd

Total 23.89

2019 Professional Hand-HarvestEWM Control Strategy

"p

"p

"p

"r

!(!(

!(

!(!(

!(!(

!( !(

!(!(!(!(!(

!(!(!( !(!(

!(!(

!(

!(

!(

!(

!(!(!(

!(

!(!(!(!(

!(!(

!(

!(!(

!(

!(!(!(!(

!(!(

!(!(

!(!(!(!(!(!(!(

!(!(!(!( !(

!(

!(

!(

!(!(!(!(!(!(!(!(!(!(

!(!(

!(

!(

!(!(

!(

!(!(!(!(!(!(!(!(!(!(!(

!(!(

!(!( !(

!(

!(!(!(!(!(!( !(!(!(

!(!(!(!(

!(!(!(!(!(!(!(!(!(!(!(!( !(!(

!(!( !(!( !(!(

!(

!(!(!(!(!(

!(!(

!(

!(!(!(!(

!(

!(

!(

!(!(!(!(!(!(!(

!(

!(!(!(!(!(!(!(!(!(

!(

!(!(!(

!(!(!(!(

!(!(!(!(

!(!(!(!(!(!(!(

!(!(!(!(!(!(!(!(

!(!(!(!(!(!(!(!(!(!(!(

!(!(!(!(!(!(

!(

!(

!(!(

!(

!(!(

!(

!(!(!(

!(

!(!(

!(

!(!(

!(!(!(

!(!(!(!(!(!(

!(!(

!(!(!(!(!(

!(

!(

A-19

E-19

D-19

C-19

B-19

.815 Prosper Road

De Pere, WI 54115920.338.8860

www.onterra-eco.com

Sources:Roads and Hydro: WDNRBathymetry: Onterra, 2015Aquatic Plants: Onterra, 2019Map Date: October 7, 2019 TWH Project Location in Wisconsin

k

900

FeetLegend

September 2019EWM Survey Results

Waushara County, WisconsinSilver Lake2019 Priority

Hand-Harvest Site

Map 2September 2019 HWM/EWM LocationsHighly Scattered Single or Few Plants!(

Clump of Plants!(


Scattered Dominant Highly Dominant Surface Matting

"p

"p

"p

"r

!(!(

!(

!(!(

!(!(

!( !(

!(!(!(!(!(

!(!(!( !(!(

!(!(

!(

!(

!(

!(

!(!(!(

!(

!(!(!(!(

!(!(

!(

!(!(

!(

!(!(!(!(

!(!(

!(!(

!(!(!(!(!(!(!(

!(!(!(!( !(

!(

!(

!(

!(!(!(!(!(!(!(!(!(!(

!(!(

!(

!(

!(!(

!(

!(!(!(!(!(!(!(!(!(!(!(

!(!(

!(!( !(

!(

!(!(!(!(!(!( !(!(!(

!(!(!(!(

!(!(!(!(!(!(!(!(!(!(!(!( !(!(

!(!( !(!( !(!(

!(

!(!(!(!(!(

!(!(

!(

!(!(!(!(

!(

!(

!(

!(!(!(!(!(!(!(

!(

!(!(!(!(!(!(!(!(!(

!(

!(!(!(

!(!(!(!(

!(!(!(!(

!(!(!(!(!(!(!(

!(!(!(!(!(!(!(

!(!(!(!(!(!(!(!(!(!(!(!(

!(!(!(!(!(!(

!(

!(

!(!(

!(

!(!(

!(

!(!(!(

!(

!(!(

!(

!(!(

!(!(!(

!(!(!(!(!(!(

!(!(

!(!(!(!(!(

!(

!(

O

FT-20

A

CT

F

D

E

I

B

H

S

L

J

U

P

G

N

RQ

K

M

.815 Prosper Road

De Pere, WI 54115920.338.8860

www.onterra-eco.com

Sources:Roads and Hydro: WDNRBathymetry: Onterra, 2015Aquatic Plants: Onterra, 2019Map Date: December 10, 2019 TWH Project Location in Wisconsin

k

900

FeetLegend

Proposed 2020 HWMManagement Strategy

Waushara County, WisconsinSilver Lake

Map 32020 PriorityHand-Harvest Site2019 PriorityHand-Harvest SiteProposed 2020 HerbicideTreatment Area

September 2019 HWM/EWM LocationsHighly Scattered Single or Few Plants!(

Clump of Plants!(



Site Acres PriorityA 2.94 1stB 0.90 3rdC 2.02 1stD 1.48 2ndE 1.08 2ndF 1.36 1stG 0.32 3rdH 0.81 2ndI 0.59 2ndJ 0.50 3rdK 0.15 3rdL 0.62 3rdM 0.12 3rdN 0.27 2ndO 0.13 3rdP 0.29 2ndQ 0.24 3rdR 0.23 2ndS 0.71 2ndT 1.49 1stU 0.50 2nd

Total 16.77

2019 Professional Hand-HarvestHWM Control Strategy

Site Proposed Acres

Avg Depth (ft)

Volume (acre/ft)

FT-20 11.6 10.7 124.1Total 11.6 124.1

2020 Preliminary Control StrategyHerbicide Spot Treatment

"p

!(

!(!(

!(

!(!(

!( !(!(!(

!(

!(

!(

!(!(

!(

!(

!(!(

!(!(!(

!(!(!(

!(!(!(!(

!(

!(

!(!( !(

!(!(

!(

!(

!(

!(!(!(

!(

!(!(

!(

!(

!(

!(

!(

!(

!(

!(!(!(!(

!(

!(

!(

.Map 4

815 Prosper RoadDe Pere, WI 54115

920.338.8860www.onterra-eco.com

Sources:Roads and Hydro: WDNRBathymetry: Onterra, 2015Aquatic Plants: Onterra, 2019Map Date: November 26, 2019 AMS Project Location in Wisconsin

k

220

FeetLegend

September 2019 HWM/EWM Locations

"p

"p

"p

"r

Highly Scattered Single or Few Plants!(

Clump of Plants!(



2020 Preliminary Herbicide Treatment Site

Silver LakeWaushara County, Wisconsin2020 Proposed HWM

Herbicide Control Strategy

Extent of Large Map in Black

PDU Rate PDU(per acre-ft) Total

FT-20 11.6 10.7 124.1 3.5 434.42

Average Depth (feet)

Volume (acre-feet)

Fox Tail Bay Preliminary ProcellaCOR Treatment AreaSite Acres

A APPENDIX A 2019 EWM Hand-Harvesting Report – Aquatic Plant Management, LLC

Silver Lake Dive ReportSummary by Location - All Dates*Priority Areas as Defined by SLMD

Date (All)

Priority Areas* Sum of Time Underwater Sum of AIS CF RemovedFoxtail 121.63 1075.00E-19 (4) 4.84 8.00D-19 (2) 6.17 9.50C-19 (5) 5.00 7.00B-19 (3) 8.41 12.00A-19 (1) 20.91 46.0024 0.25 0.0022 1.17 2.0021 1.59 0.5019 3.17 3.0018 2.67 2.5017 0.50 0.0016 5.08 24.5015 0.42 0.0014 8.09 7.5013 9.84 27.5012 0.33 0.0011 0.58 2.5010 2.08 3.509 2.59 2.508 2.66 6.507 1.41 1.506 2.25 4.005 0.92 1.003 0.25 0.00Grand Total 212.81 1246.50

Silver Lake Dive Report2019 Dive Map

Silver Lake Dive ReportSummary by Location - August*Priority Areas as Defined by SLMD

Date (Multiple Items)

Priority Areas* Sum of Time Underwater Sum of AIS CF RemovedFoxtail 30.68 169.00E-19 (4) 1.67 0.00D-19 (2) 2.00 4.00C-19 (5) 1.00 1.00B-19 (3) 5.83 7.50A-19 (1) 4.50 3.5022 0.50 1.0019 2.42 2.0018 2.00 1.0014 4.67 2.5013 4.08 13.009 1.08 0.508 1.50 2.507 0.58 0.506 0.67 1.00Grand Total 63.18 209.00

Silver Lake Dive ReportSummary by Location - July*Priority Areas as Defined by SLMD


Priority Areas* Sum of Time Underwater Sum of AIS CF RemovedFoxtail 12.91 131.00E-19 (4) 0.92 0.50D-19 (2) 2.08 3.50C-19 (5) 3.50 1.50B-19 (3) 0.75 0.50A-19 (1) 11.83 20.0024 0.25 0.0022 0.67 1.0021 1.59 0.5019 0.75 1.0018 0.67 1.5017 0.50 0.0016 5.08 24.5015 0.42 0.0014 3.42 5.0013 5.76 14.5012 0.33 0.0010 0.83 1.009 0.76 1.508 0.75 1.507 0.58 0.506 1.16 2.005 0.92 1.003 0.25 0.00Grand Total 56.68 212.50

Silver Lake Dive ReportSummary by Location - June*Priority Areas as Defined by SLMD


Priority Areas* Sum of Time Underwater Sum of AIS CF RemovedFoxtail 78.04 775.00E-19 (4) 2.25 7.50D-19 (2) 2.09 2.00C-19 (5) 0.50 4.50B-19 (3) 1.83 4.00A-19 (1) 4.58 22.5011 0.58 2.5010 1.25 2.509 0.75 0.508 0.41 2.507 0.25 0.506 0.42 1.00Grand Total 92.95 825.00

Silver Lake Dive ReportDive Data

Date Dive Location Latitude Longitude Time Underwater AIS CF Removed AIS Density Avg Water Depth Native By-Catch (CF) Native Species Native Density Substrate Type6/10/2019 Foxtail 44.04689 -89.22010 1.33 6.50 Low 9.0 2.0 Pondweeds High Organic6/10/2019 Foxtail 44.04689 -89.22010 0.33 3.00 Medium 10.5 1.0 Pondweeds High Organic6/10/2019 Foxtail 44.04749 -89.21964 1.00 19.00 Medium 11.5 2.0 Pondweeds High Organic6/10/2019 Foxtail 44.04756 -89.21970 0.58 7.00 Low 9.0 0.5 Pondweeds High Organic6/10/2019 Foxtail 44.04744 -89.21971 0.83 12.00 Medium 11.0 1.0 Pondweeds High Organic6/10/2019 Foxtail 44.04760 -89.21984 0.75 3.00 Low 12.5 <0.5 Pondweeds High Organic6/10/2019 Foxtail 44.04765 -89.21986 0.83 2.50 Low 9.5 <0.5 Pondweeds High Organic6/11/2019 Foxtail 44.04720 -89.21992 0.75 5.00 Low 10.0 1.0 Pondweeds High Organic6/11/2019 Foxtail 44.04720 -89.21992 0.92 14.00 Medium 10.5 1.5 Pondweeds High Organic6/11/2019 Foxtail 44.04704 -89.21989 1.00 7.50 Low 14.5 1.0 Pondweeds High Organic6/11/2019 Foxtail 44.04708 -89.21995 1.33 4.00 Low 12.0 0.5 Pondweeds High Organic6/11/2019 Foxtail 44.04782 -89.22010 0.58 8.00 Medium 10.0 1.0 Pondweeds High Organic6/11/2019 Foxtail 44.04729 -89.22003 1.33 9.00 Low 12.0 1.5 Pondweeds High Organic6/11/2019 Foxtail 44.04793 -89.21971 0.50 3.00 Low 10.0 <0.5 Pondweeds High Organic6/11/2019 Foxtail 44.04788 -89.21990 0.75 1.50 Low 9.0 <0.5 Pondweeds High Organic6/11/2019 Foxtail 44.04778 -89.21976 1.08 8.00 Low 12.0 1.5 Pondweeds High Organic6/11/2019 Foxtail 44.04790 -89.21978 0.33 0.50 Low 12.0 <0.5 Pondweeds High Organic6/11/2019 Foxtail 44.04710 -89.21989 0.08 0.50 Low 12.0 <0.5 Pondweeds High Organic6/11/2019 Foxtail 44.04710 -89.21989 0.58 3.50 Low 12.0 1.0 Pondweeds High Organic6/12/2019 Foxtail 44.04799 -89.21990 1.17 2.00 Low 10.0 <0.5 Pondweeds High Organic6/12/2019 Foxtail 44.04691 -89.21967 1.25 3.50 Medium 4.5 0.0 Pondweeds High Organic/Sand6/12/2019 Foxtail 44.04784 -89.21991 0.83 1.50 Low 11.0 0.5 Pondweeds High Organic6/12/2019 Foxtail 44.04818 -89.22017 0.58 1.00 Low 4.5 0.0 Pondweeds Medium Organic/Sand6/12/2019 Foxtail 44.04818 -89.22017 0.50 3.50 Medium 3.5 0.0 Pondweeds Low Organic/Sand6/12/2019 Foxtail 44.04836 -89.22036 1.42 5.50 Medium 11.5 0.5 Pondweeds High Organic6/12/2019 Foxtail 44.04799 -89.21999 0.67 3.00 Low 10.0 <0.5 Pondweeds High Organic6/12/2019 Foxtail 44.04796 -89.21999 0.50 1.00 Low 10.0 <0.5 Pondweeds High Organic6/12/2019 Foxtail 44.04691 -89.21967 1.25 3.00 Medium 4.5 0.0 Pondweeds Medium Organic/Sand6/12/2019 Foxtail 44.04784 -89.21991 1.33 6.00 Low 13.0 2.0 Pondweeds High Organic6/12/2019 Foxtail 44.04836 -89.22036 1.17 3.50 Low 3.5 0.0 Pondweeds Low Organic/Sand6/12/2019 Foxtail 44.04855 -89.22016 1.00 17.50 Medium 11.5 2.0 Pondweeds High Organic6/12/2019 Foxtail 44.04836 -89.22036 0.58 1.00 Low 11.5 0.0 Pondweeds High Organic6/13/2019 Foxtail 44.04889 -89.22002 2.42 4.50 Medium 3.0 0.0 None Low Organic/Sand6/13/2019 Foxtail 44.04837 -89.22021 1.83 11.00 Low 9.5 2.5 Pondweeds High Organic6/13/2019 Foxtail 44.04904 -89.22079 1.33 18.00 High 9.5 <0.5 Pondweeds Medium Organic6/13/2019 Foxtail 44.04904 -89.22079 0.42 3.00 High 10.5 0.5 Pondweeds Low Organic6/13/2019 Foxtail 44.04889 -89.22002 2.50 7.50 Medium 3.0 0.0 None Low Sand6/13/2019 Foxtail 44.04887 -89.22021 1.92 10.00 Low 10.5 2.0 Pondweeds Medium Organic6/13/2019 Foxtail 44.04904 -89.22079 1.08 29.00 High 11.5 1.0 Pondweeds Low Organic6/13/2019 Foxtail 44.04904 -89.22079 0.33 4.00 High 10.5 0.0 None Medium Organic6/14/2019 Foxtail 44.04872 -89.22053 1.33 16.50 High 9.5 <0.5 Pondweeds Low Organic6/14/2019 Foxtail 44.04900 -89.22044 3.42 18.00 High 2.5 0.0 None Low Organic/Sand6/14/2019 Foxtail 44.04872 -89.22053 1.17 13.50 High 10.0 0.0 None Low Organic6/14/2019 Foxtail 44.04900 -89.22044 3.67 16.50 High 2.5 0.0 None Low Organic6/17/2019 Foxtail 44.04861 -89.22061 1.08 12.50 High 9.0 0.0 None Low Organic6/17/2019 Foxtail 44.04865 -89.22060 1.00 13.00 High 9.0 0.0 None Low Organic6/17/2019 Foxtail 44.04872 -89.22064 1.75 14.00 High 7.0 <0.5 None Low Organic6/17/2019 Foxtail 44.04887 -89.22047 1.00 15.00 High 9.0 0.5 Pondweeds Low Organic6/17/2019 Foxtail 44.04887 -89.22047 0.50 7.00 High 8.5 0.0 None Low Organic


Date Dive Location Latitude Longitude Time Underwater AIS CF Removed AIS Density Avg Water Depth Native By-Catch (CF) Native Species Native Density Substrate Type6/18/2019 Foxtail 44.04900 -89.22047 2.00 14.50 High 10.0 <0.5 Pondweeds Low Organic6/18/2019 Foxtail 44.04898 -89.22050 1.17 13.50 High 8.0 0.0 None Low Organic6/18/2019 Foxtail 44.04898 -89.22050 0.92 16.00 High 8.0 0.0 None Low Organic6/18/2019 Foxtail 44.04898 -89.22050 1.17 9.00 High 8.5 0.0 None Low Organic6/18/2019 Foxtail 44.04897 -89.22057 0.92 18.50 High 8.0 0.0 None Low Organic6/18/2019 Foxtail 44.04900 -89.22047 1.42 21.00 High 7.0 <0.5 Pondweeds Low Organic6/18/2019 Foxtail 44.04898 -89.22050 1.08 17.00 High 7.0 1.0 Pondweeds Low Organic6/18/2019 Foxtail 44.04897 -89.22057 1.00 22.50 High 7.0 1.0 Pondweeds Low Organic6/19/2019 A-19 (1) 44.04902 -89.22797 1.50 1.50 Low 19.0 0.0 None Medium Organic6/19/2019 A-19 (1) 44.04882 -89.22697 0.75 2.00 Low 17.0 0.0 None Low Organic/Gravel6/19/2019 D-19 (2) 44.05773 -89.23317 0.67 0.00 Low 12.0 0.0 None Low Organic6/19/2019 B-19 (3) 44.05030 -89.23463 1.33 3.50 Low 8.5 <0.5 Elodea Medium Organic6/19/2019 E-19 (4) 44.05737 -89.23261 0.58 0.50 Low 8.5 0.0 Elodea Medium Organic6/19/2019 Foxtail 44.04872 -89.22083 1.42 24.00 High 8.0 0.0 None Low Organic6/19/2019 Foxtail 44.04908 -89.22068 1.00 12.50 High 8.0 0.5 Pondweeds Low Organic6/19/2019 Foxtail 44.04902 -89.22062 1.50 40.50 High 8.0 0.5 Pondweeds Low Organic6/19/2019 Foxtail 44.04902 -89.22062 0.83 20.50 High 8.0 0.5 Pondweeds Low Organic6/19/2019 Foxtail 44.04901 -89.22075 1.08 16.00 High 8.0 0.5 Pondweeds Low Organic6/19/2019 Foxtail 44.04901 -89.22075 0.58 14.00 High 8.0 0.5 Pondweeds Low Organic6/20/2019 A-19 (1) 44.04908 -89.22581 1.58 16.00 Medium 12.0 <0.5 None Medium Organic/Gravel6/20/2019 A-19 (1) 44.04908 -89.22581 0.75 3.00 Low 13.0 0.0 None Medium Organic/Gravel6/20/2019 Foxtail 44.04882 -89.22083 1.00 24.00 High 10.0 0.0 None Low Organic6/20/2019 Foxtail 44.04880 -89.22081 0.67 7.00 High 9.0 0.0 None Low Organic6/20/2019 Foxtail 44.04904 -89.22081 1.08 13.00 Medium 6.0 0.0 None Low Organic6/20/2019 Foxtail 44.04904 -89.22081 0.42 9.00 Medium 8.0 0.0 None Low Organic6/20/2019 Foxtail 44.04876 -89.22058 1.08 15.00 High 7.0 0.5 Pondweeds Low Organic6/20/2019 Foxtail 44.04880 -89.22072 1.08 31.00 High 7.0 0.5 Pondweeds Low Organic6/20/2019 Foxtail 44.04877 -89.22066 0.33 5.50 High 7.0 <0.5 Pondweeds Low Organic6/20/2019 Foxtail 44.04903 -89.22072 0.75 13.00 High 6.0 0.5 Pondweeds Low Organic6/20/2019 Foxtail 44.04908 -89.22072 0.83 6.00 Medium 5.5 <0.5 Pondweeds Medium Organic6/20/2019 Foxtail 44.04907 -89.22076 0.83 9.50 Medium 3.0 <0.5 Pondweeds Medium Organic/Sand6/21/2019 B-19 (3) 44.05032 -89.23452 0.25 0.50 Low 12.0 0.0 Coontail Low Organic6/21/2019 B-19 (3) 44.05032 -89.23454 0.25 0.00 Low 14.0 0.0 Coontail Low Organic6/21/2019 C-19 (5) 44.05144 -89.23658 0.33 4.00 Medium 14.0 <0.5 Coontail Medium Organic6/21/2019 C-19 (5) 44.05144 -89.23658 0.17 0.50 Low 14.0 0.0 Coontail Medium Organic6/21/2019 6 44.05479 -89.23621 0.42 1.00 Low 15.0 <0.5 Coontail Medium Organic6/21/2019 7 44.05676 -89.23601 0.25 0.50 Low 13.0 <0.5 Pondweeds Medium Organic/Gravel6/21/2019 8 44.05031 -89.22240 0.33 2.00 Medium 10.0 0.0 None Low Organic6/21/2019 8 44.05031 -89.22240 0.08 0.50 Low 10.0 0.0 None Low Organic6/21/2019 11 44.05824 -89.24461 0.58 2.50 Low 16.0 0.5 Pondweeds Medium Organic6/21/2019 D-19 (2) 44.05790 -89.23349 1.42 2.00 Medium 15.0 <0.5 Pondweeds Medium Organic6/21/2019 E-19 (4) 44.05657 -89.23180 1.67 7.00 High 11.0 0.0 None Low Organic/Sand6/21/2019 9 44.04713 -89.22190 0.75 0.50 Low 13.5 0.0 None Medium Organic6/21/2019 10 44.05593 -89.23949 0.50 0.00 Low 12.5 0.0 None Low Sand6/21/2019 10 44.05593 -89.23949 0.75 2.50 Medium 17.5 0.0 None Low Organic/Sand7/15/2019 E-19 (4) 44.05133 -89.23656 0.92 0.50 Low 14.5 <0.5 Pondweeds Medium Organic/Sand7/15/2019 C-19 (5) 44.05133 -89.23673 1.00 0.50 Low 20.0 <0.5 Pondweeds High Organic7/15/2019 B-19 (3) 44.05033 -89.23452 0.75 0.50 Low 13.0 0.0 Pondweeds High Organic7/15/2019 A-19 (1) 44.04881 -89.22761 0.58 4.00 Medium 20.0 <0.5 Pondweeds High Organic7/15/2019 A-19 (1) 44.05027 -89.22778 0.92 4.00 Medium 17.0 <0.5 Pondweeds High Organic/Sand


Date Dive Location Latitude Longitude Time Underwater AIS CF Removed AIS Density Avg Water Depth Native By-Catch (CF) Native Species Native Density Substrate Type7/16/2019 A-19 (1) 44.04914 -89.22607 1.83 2.00 Low 15.0 <0.5 Pondweeds High Organic/Sand7/16/2019 D-19 (2) 44.05804 -89.23330 0.83 2.50 Low 15.0 <0.5 Elodea High Organic7/16/2019 13 44.06175 -89.24350 0.42 0.50 Low 11.0 0.0 Pondweeds High Organic7/16/2019 16 44.06023 -89.23741 0.33 0.50 Low 11.5 0.0 Pondweeds High Organic7/16/2019 A-19 (1) 44.04896 -89.22799 1.17 5.00 Medium 15.0 0.0 Pondweeds High Organic7/16/2019 6 44.05498 -89.23548 0.58 0.50 Low 13.0 0.0 Pondweeds High Organic7/16/2019 D-19 (2) 44.05804 -89.23293 0.50 0.50 Low 15.0 0.0 Pondweeds High Organic7/17/2019 14 44.06019 -89.24451 1.75 4.50 Low 16.5 0.5 Pondweeds High Organic7/17/2019 7 44.05677 -89.23618 0.33 0.50 Low 10.0 0.0 Pondweeds High Organic7/17/2019 12 44.05345 -89.22614 0.33 0.00 Low 15.5 0.0 Pondweeds High Organic7/17/2019 8 44.05042 -89.22233 0.42 1.00 Low 14.0 0.0 Pondweeds High Organic7/17/2019 10 44.05582 -89.23940 0.58 0.50 Low 17.0 0.0 Pondweeds High Organic/Gravel7/17/2019 21 44.05576 -89.23091 0.42 0.00 Low 15.5 0.0 Pondweeds Medium Organic7/17/2019 18 44.04998 -89.22890 0.67 1.50 Low 16.0 0.0 Pondweeds High Organic7/17/2019 15 44.05670 -89.24255 0.42 0.00 17.0 0.0 Pondweeds High Organic7/18/2019 8 44.05045 -89.22249 0.33 0.50 Low 13.0 0.0 Elodea Medium Organic7/18/2019 9 44.05001 -89.22244 0.42 0.50 Low 10.0 0.0 Coontail High Organic7/18/2019 9 44.04736 -89.22250 0.17 0.50 Low 8.5 0.0 Pondweeds High Organic/Sand7/18/2019 9 44.04769 -89.22267 0.17 0.50 Low 8.5 0.0 Pondweeds High Organic/Sand7/18/2019 19 44.04863 -89.22379 0.25 0.50 Low 11.0 0.0 Pondweeds High Organic/Sand7/18/2019 19 44.04902 -89.22471 0.50 0.50 Low 13.0 0.0 Pondweeds High Organic/Sand7/18/2019 5 44.05130 -89.23669 0.92 1.00 Low 17.0 0.0 Pondweeds High Organic7/18/2019 3 44.05027 -89.23429 0.25 0.00 Low 7.0 0.0 Elodea High Organic/Sand7/18/2019 17 44.05304 -89.23804 0.25 0.00 Low 15.0 0.0 Pondweeds High Organic7/18/2019 17 44.05428 -89.23707 0.25 0.00 Low 8.5 0.0 Pondweeds High Organic7/18/2019 13 44.06133 -89.24258 0.17 0.50 Low 7.0 0.0 Elodea High Organic7/18/2019 6 44.05479 -89.23531 0.58 1.50 Medium 18.0 <0.5 Elodea High Organic7/18/2019 13 44.05598 -89.23801 0.25 0.50 Low 9.0 0.0 None High Organic7/18/2019 10 44.05584 -89.23801 0.25 0.50 Low 14.5 0.0 None High Organic/Sand7/18/2019 7 44.05633 -89.23798 0.25 0.00 Low 15.0 0.0 None Medium Sand7/18/2019 24 44.05631 -89.24203 0.25 0.00 Low 12.0 0.0 None Medium Organic7/19/2019 22 44.06136 -89.24437 0.42 0.50 Low 19.0 0.0 None Medium Organic7/19/2019 13 44.06222 -89.24304 0.42 0.50 Low 6.5 0.0 None High Organic7/19/2019 13 44.06212 -89.24142 1.33 10.00 Medium 13.0 0.5 Pondweeds High Organic7/19/2019 22 44.06114 -89.23971 0.25 0.50 Low 14.0 0.0 None Medium Organic7/19/2019 16 44.06041 -89.23812 0.33 1.50 Low 13.0 0.5 Pondweeds High Organic/Sand7/19/2019 16 44.06013 -89.23749 0.25 1.50 Medium 14.0 <0.5 Pondweeds High Organic7/19/2019 16 44.05992 -89.23675 0.83 12.00 Medium 16.0 1.0 Chara High Organic/Sand7/19/2019 21 44.05479 -89.22877 1.17 0.50 Low 17.5 0.0 Pondweeds Medium Organic/Sand7/22/2019 Foxtail 44.04838 -89.22030 1.58 10.00 Medium 13.0 2.5 Pondweeds High Organic7/22/2019 Foxtail 44.04861 -89.22018 1.58 27.50 Medium 12.0 3.0 Pondweeds High Organic7/22/2019 Foxtail 44.04869 -89.22042 1.00 21.50 High 13.0 1.0 Pondweeds Medium Organic/Sand7/22/2019 Foxtail 44.04767 -89.21938 1.75 13.00 High 5.0 0.5 Pondweeds Low Sand7/23/2019 Foxtail 44.04708 -89.21955 3.83 17.00 High 5.5 0.0 None Low Sand7/23/2019 Foxtail 44.04685 -89.22043 3.17 42.00 Medium 12.5 5.0 Pondweeds High Organic7/24/2019 A-19 (1) 44.04876 -89.22784 2.75 2.00 Low 9.0 0.0 None Low Organic7/24/2019 D-19 (2) 44.05790 -89.23349 0.75 0.50 Low 13.0 0.0 None Medium Organic7/24/2019 13 44.06214 -89.24273 2.25 1.50 Low 7.5 <0.5 Pondweeds Medium Organic7/24/2019 16 44.06048 -89.23807 1.17 4.00 Medium 9.0 <0.5 Pondweeds High Organic


Date Dive Location Latitude Longitude Time Underwater AIS CF Removed AIS Density Avg Water Depth Native By-Catch (CF) Native Species Native Density Substrate Type7/25/2019 C-19 (5) 44.05134 -89.23676 2.50 1.00 Low 9.0 <0.5 Pondweeds Low Organic7/25/2019 16 44.05969 -89.23658 2.17 5.00 Medium 10.0 0.0 Pondweeds Medium Organic7/25/2019 14 44.05641 -89.24178 1.67 0.50 Low 11.5 0.0 None Medium Organic7/25/2019 13 44.05958 -89.23639 0.92 1.00 Low 8.0 0.5 Pondweeds Medium Organic7/26/2019 A-19 (1) 44.04876 -89.22784 2.00 1.50 Low 8.0 <0.5 None Medium Organic7/26/2019 A-19 (1) 44.04880 -89.22717 1.50 1.00 Low 16.0 0.0 None Low Organic7/26/2019 A-19 (1) 44.04888 -89.22649 1.08 0.50 Low 10.5 0.0 None Medium Organic8/13/2019 B-19 (3) 44.05034 -89.23467 3.33 4.00 Low 14.0 1.5 Pondweeds High Organic8/13/2019 13 44.06198 -89.24287 0.58 4.00 Low 9.0 0.5 Pondweeds Medium Organic8/13/2019 A-19 (1) 44.04880 -89.22690 2.08 1.00 Low 12.0 0.0 None Low Organic8/14/2019 8 44.05069 -89.22229 1.50 2.50 Low 9.0 <0.5 None Medium Organic8/14/2019 D-19 (2) 44.05653 -89.23169 2.00 4.00 Low 15.5 2.0 None Medium Organic8/14/2019 13 44.06211 -89.24360 0.75 2.00 Low 12.5 0.5 Pondweeds Medium Organic8/14/2019 14 44.06069 -89.24591 2.75 0.50 Low 9.0 0.0 None Medium Sand8/15/2019 7 44.05668 -89.23628 0.58 0.50 Low 9.0 <0.5 Pondweeds Medium Organic8/15/2019 6 44.05481 -89.23606 0.67 1.00 Low 12.0 0.0 None Medium Organic/Sand8/15/2019 C-19 (5) 44.05133 -89.23664 1.00 1.00 Low 14.0 0.0 None Medium Organic8/15/2019 22 44.06131 -89.24005 0.50 1.00 Low 11.0 0.5 Pondweeds Low Organic8/15/2019 13 44.06198 -89.24142 0.75 3.00 Low 14.0 1.0 Pondweeds Medium Organic8/15/2019 B-19 (3) 44.05035 -89.23441 0.83 0.50 Low 14.0 0.0 None High Organic8/16/2019 A-19 (1) 44.04879 -89.22685 2.42 2.50 Low 14.0 0.0 None Low Organic8/16/2019 14 44.06080 -89.24567 1.92 2.00 Low 6.5 <0.5 Chara Medium Organic/Sand8/16/2019 9 44.04752 -89.22269 1.08 0.50 Low 8.0 0.0 None Low Organic/Sand8/19/2019 19 44.04905 -89.22516 2.42 2.00 Low 11.0 0.5 None Medium Organic8/19/2019 B-19 (3) 44.05074 -89.23357 1.67 3.00 Low 12.5 0.0 None Medium Organic8/19/2019 E-19 (4) 44.05655 -89.23164 1.67 0.00 Low 11.0 0.0 None Medium Organic8/20/2019 Foxtail 44.04762 -89.22003 2.67 32.00 Medium 13.0 4.0 Pondweeds High Organic8/20/2019 Foxtail 44.04638 -89.22098 0.92 17.50 Medium 10.0 1.0 Pondweeds Medium Organic8/20/2019 Foxtail 44.04824 -89.21982 1.00 11.00 Medium 9.0 1.5 Pondweeds Medium Organic8/21/2019 Foxtail 44.04731 -89.21965 1.50 6.50 Medium 8.5 1.0 Pondweeds High Organic8/21/2019 Foxtail 44.04731 -89.21965 1.00 7.00 Medium 8.5 1.5 Pondweeds High Organic8/21/2019 Foxtail 44.04755 -89.21994 1.25 6.50 Low 9.0 1.0 Chara High Organic8/21/2019 Foxtail 44.04755 -89.21994 1.50 5.00 Low 9.5 1.5 Chara High Organic8/21/2019 Foxtail 44.04712 -89.22020 0.58 5.00 Low 8.5 1.0 Chara High Organic8/22/2019 Foxtail 44.04703 -89.21976 1.25 6.00 Medium 8.5 1.5 Chara High Organic8/22/2019 Foxtail 44.04703 -89.21976 0.92 7.50 Medium 9.5 2.0 Chara High Organic8/23/2019 Foxtail 44.04703 -89.21976 1.25 12.00 Medium 12.0 3.0 Pondweeds High Organic8/23/2019 Foxtail 44.04717 -89.22002 1.50 10.00 Medium 11.0 2.0 Chara High Organic8/23/2019 Foxtail 44.04681 -89.21997 1.25 9.00 Medium 11.0 1.0 Chara High Organic8/23/2019 Foxtail 44.04715 -89.21989 1.25 8.50 Low 10.0 0.5 Chara High Organic8/26/2019 18 44.05005 -89.22894 1.25 0.50 Low 10.0 <0.5 Chara High Organic/Sand8/26/2019 13 44.06211 -89.24132 0.92 2.00 Low 9.5 <0.5 Chara High Organic/Sand8/26/2019 13 44.06208 -89.24145 1.08 2.00 Low 9.5 <0.5 Chara High Organic/Sand8/26/2019 18 44.04991 -89.22886 0.75 0.50 Low 10.0 <0.5 Chara High Organic/Sand8/26/2019 Foxtail 44.04661 -89.22021 0.75 2.00 Low 7.5 0.5 Pondweeds High Organic/Sand8/26/2019 Foxtail 44.04664 -89.22013 1.00 2.50 Low 7.5 0.5 Pondweeds High Organic/Sand8/27/2019 Foxtail 44.04667 -89.21992 0.83 3.00 Low 7.0 0.5 Pondweeds High Organic/Sand8/27/2019 Foxtail 44.04687 -89.21991 1.58 2.00 Low 7.5 0.5 Pondweeds High Organic/Sand8/27/2019 Foxtail 44.04694 -89.21980 1.17 3.50 Medium 7.0 0.5 Pondweeds High Organic/Sand8/27/2019 Foxtail 44.04702 -89.21971 1.17 2.00 Low 7.0 0.5 Pondweeds High Organic/Sand8/27/2019 Foxtail 44.04720 -89.21958 1.42 3.50 Medium 6.5 0.5 Pondweeds High Organic/Sand8/27/2019 Foxtail 44.04730 -89.21957 1.67 2.50 Low 6.5 0.5 Pondweeds High Organic/Sand8/28/2019 Foxtail 44.04732 -89.21947 1.08 1.50 Low 8.0 <0.5 Chara High Organic8/28/2019 Foxtail 44.04732 -89.21947 0.42 0.50 Low 8.0 <0.5 Chara High Organic8/28/2019 Foxtail 44.04743 -89.21944 1.33 2.00 Low 6.0 1.0 Chara High Organic8/28/2019 Foxtail 44.04743 -89.21944 0.42 0.50 Low 6.0 <0.5 Chara High Organic

Silver Lake Dive ReportPriorty Areas

BAPPENDIX B

Point-Intercept Aquatic Macrophyte Survey Results (2012-2019)


January 2020 19

4.0 APPENDIX BChiSquareAnalysisforpoint‐interceptsurveysfrom2012‐2019inSilverLake.

2012 2013 2014 2015 2017 2018 2019 % Change Direction

Myriophyllum sibiricum X spicatum Hybrid w atermilfoil 25.3 33.3 7.8 20.0 0.2 1.7 2.3 32.3 ▲Ceratophyllum demersum Coontail 32.9 32.9 42.5 36.3 20.2 25.5 21.9 -14.1 ▼Bidens beckii Water marigold 0.0 0.0 0.2 0.0 0.4 1.1 2.3 111.7 ▲Myriophyllum sibiricum Northern w atermilfoil 0.6 5.4 0.7 0.2 0.0 0.0 0.0 -Ranunculus aquatilis White w ater crow foot 0.0 0.0 0.2 0.4 0.0 0.0 0.2 ▲Utricularia geminiscapa Tw in-stemmed bladderw ort 0.0 0.0 0.0 0.0 0.0 0.2 0.0 -100.0 ▼Nymphaea odorata White w ater lily 0.2 0.0 0.0 0.0 0.0 0.0 0.0 -Ceratophyllum echinatum Spiny hornw ort 0.0 0.0 0.0 0.0 0.2 0.0 0.0 -

Potamogeton crispus Curly-leaf pondw eed 0.2 0.0 0.0 0.2 1.1 0.0 0.2 ▲Chara spp. & Nitella spp. Muskgrasses & Stonew orts 33.8 25.1 30.0 23.9 25.7 33.5 23.6 -29.4 ▼Chara spp. Muskgrasses 28.7 15.9 19.2 17.4 22.2 31.3 16.6 -47.1 ▼Elodea canadensis Common w aterw eed 27.8 35.1 28.2 19.1 0.0 1.3 2.3 76.4 ▲Najas guadalupensis Southern naiad 24.7 21.3 22.6 16.5 3.7 9.7 7.0 -27.5 ▼Vallisneria americana Wild celery 11.0 8.9 11.6 12.4 9.8 14.3 13.9 -2.5 ▼Potamogeton gramineus Variable-leaf pondw eed 20.7 13.6 10.7 11.1 3.5 15.1 10.7 -29.4 ▼Fissidens spp. & Fontinalis spp. Aquatic Moss 5.5 10.1 7.4 4.8 0.0 9.7 18.3 88.1 ▲Nitella spp. Stonew orts 8.0 9.4 11.4 8.5 3.7 2.2 7.2 235.1 ▲Stuckenia pectinata Sago pondw eed 6.5 5.1 6.5 8.9 7.4 10.4 4.4 -57.7 ▼Potamogeton friesii Fries' pondw eed 2.1 3.4 2.2 11.7 4.6 3.9 8.2 110.7 ▲Potamogeton zosteriformis Flat-stem pondw eed 1.5 2.2 2.0 2.6 6.1 7.3 6.9 -6.6 ▼Potamogeton praelongus White-stem pondw eed 4.6 4.0 8.5 4.8 1.5 4.1 4.2 2.1 ▲Potamogeton pusillus Small pondw eed 0.0 2.0 2.2 4.8 3.5 8.9 6.5 -26.9 ▼Filamentous algae Filamentous algae 7.0 2.2 3.8 13.3 1.1 0.2 2.1 870.1 ▲Potamogeton illinoensis Illinois pondw eed 4.6 2.7 4.7 5.4 1.5 0.6 1.5 135.2 ▲Najas flexilis Slender naiad 3.2 1.8 3.8 3.0 0.0 3.2 3.0 -5.9 ▼Potamogeton foliosus Leafy pondw eed 3.6 0.2 2.9 0.7 1.7 0.2 2.5 1046.5 ▲Heteranthera dubia Water stargrass 0.6 0.2 0.2 0.0 2.4 4.3 1.7 -60.3 ▼Potamogeton strictifolius Stiff pondw eed 0.0 0.0 0.0 0.0 1.5 0.9 1.9 120.5 ▲Potamogeton natans Floating-leaf pondw eed 0.0 0.7 0.4 0.9 0.0 0.2 0.4 76.4 ▲Potamogeton amplifolius Large-leaf pondw eed 0.6 0.0 0.7 0.0 0.0 0.6 0.2 -70.6 ▼Eleocharis acicularis Needle spikerush 0.0 0.0 0.2 0.7 0.4 0.2 0.0 -100.0 ▼Potamogeton berchtoldii Slender pondw eed 0.0 0.0 0.0 0.0 0.0 0.0 0.4 ▲Freshwater sponge Freshw ater sponge 0.2 0.0 0.0 0.0 0.0 0.0 0.2 ▲Spirodela polyrhiza Greater duckw eed 0.0 0.0 0.0 0.0 0.4 0.0 0.0 -Potamogeton spirillus Spiral-fruited pondw eed 0.0 0.0 0.0 0.0 0.4 0.0 0.0 -Elodea nuttallii Slender w aterw eed 0.0 0.4 0.0 0.0 0.0 0.0 0.0 -

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

Dic

ots

No

n-d

ico

ts

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

2018-2019

Scientific Name Common Name

LFOO (%)

silverwaushara hwm managementreport2019 final

Documents