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Annual Monitoring Report

Starry Stonewort Management

Submitted to:

Invasive Species Program

Division of Ecological and Water Resources

Minnesota Department of Natural Resources

Project Summary

Lake:                  Lake Koronis

County:          Stearns / Meeker 

DOW Number:  73020002

Lake Acres:          2,968.29

Littoral Acres:          1,176

Project Details

Project Year:          4

Primary ISS Contact:           Chris Jurek

Observers:   Blue Water Science, Steve McComas, Connor McComas, Jo Stuckert, Kevin Farnum

Date(s) of Treatment(s):   7/8/19 to 9/11/19

Date(s) of Survey(s):   6/24/19 to 10/7/19

Survey Methods: P.I. plus other defined methods as listed in our protocol and repeated for the last three years.

Report Details

Date of Report: 12/31/19

Author(s) of Report: Prepared by Kevin Farnum  of Koronis Lake Association for Koronis Lake Association

Name of organization: Koronis Lake Association

Address: PO Box 333, Paynesville, MN 56362 or author is 684 Marie Court, Delano, MN  55328

Email: farnumfamiliy@hotmail.com

Phone: 763-972-6945

 Summary of Results

In this report we summarize starry stonewort monitoring data collected during 6/24 to 10/7/19 from Lake Koronis. This report fulfills the post-treatment monitoring requirements outlined by the DNR Invasive Species Program and Permit 2018-0182. Supplemental reports may be provided as additional information.

Background Context 

Starry Stonewort (Nitellopsis obtuse) was discovered in 2015 by DNR in response to a shore owner comment. At that time the predominant infestation was around the Hwy 55 access area and the adjacent bay.  In 2015 and 2016 DNR performed some chemical treatments in the access area without any success, but was able to sustain a lower level of growth with mechanical pulling in 2016.   2016 and 2017 were the years where a pilot project was initiated by the Lake Koronis Association with the help of DNR to investigate an integrated approach to the management of Starry Stonewort using mechanical pulling combined with chemical treatments.  Combinations of these management techniques were piloted in 2016 on the North end of the bay near the access referenced above and again repeated in adjacent areas in 2017.  2018 was a scale up of the smaller pilots to the whole bay and 11 other smaller areas around the lake.  2019 focus was on maintaining those areas treated in 2018 and expansion to 7 new highly infested areas around the lake.  Three of these areas were mechanically pulled prior to all 7 of them being chemically treated.  4 additional areas were added to the permit part way thru the summer, but for only mechanical pulling.  In all years the protocol was to perform a pre-survey of the treatment areas using an independent auditor and then a post-survey audit using the same independent auditor.  The raw data sheets are contained in this report, attached, as well as reprints of the infestation maps created by DNR and the third party auditor, since the onset of discovery.  Information on chemical treatments and chemical application data is also contained in this report.  The third party auditors report is also attached.

The purpose of the project was to determine a sustainable management approach to the Starry Stonewort infestation in the lake.  The project was in association with MN DNR, the University of Minnesota, and Dr. John Rogers from Clemson University.  This report summarizes the 2019 findings.

All work was completed under permit numbers and reports in response to those permit numbers:

2018-0182, 16W-3B058, 045, 043 and 2017-1198

Additional information can be found in DNR report Koronis_Stearns_2019_PI report_ISP.pdf.  

 Koronis Stearns 2019 PI report ISP(pdf)                          Kornis $19 - SSW 1-9-20(pdf)

Third Party Auditors Report

Lake Description                                          (copied from DNR LVMP report 2018)

Lake Koronis is located within the North Fork Crow River Watershed near the city of Paynesville, MN within the counties of Stearns and Meeker (Figure 1). It is a 2,968 acre lake with a littoral area of 1,176 acres. The lake’s maximum depth is 132 feet. Common aquatic plants in Lake Koronis include sago pondweed


(Stuckenia pectinata), muskgrass (Chara spp.), wild celery (Valisneria americana), flat-stem pondweed (Potamogeton zosteriformis), and coontail (Ceratophyllum demersum). Two invasive aquatic plant species are present in the lake: curly-leaf pondweed (Potamogeton crispus) and starry stonewort (Nitellopsis obtuse). Approximately 39.6% of the lake is littoral (zone where aquatic plants are likely to be found). Lake Koronis is within the North Central Hardwoods Forested Ecoregion and is considered a eutrophic lake with an average water clarity of 8.1 feet, total phosphorus mean of 35.7 ug/L, and chlorophyll-a mean of 14.2 ug/L (RMB Environmental Labs, Inc., 2018).

Map of where Koronis Lake is located in the state.

Management Summary

The protocol used for the management of Starry Stonewort on Lake Koronis followed this guideline:

Shallow areas in the pilot that are less than 4 feet in depth – mechanical pulling, this includes around docks and lifts, followed by 2 chemical treatments spaced across the summer.

Pilot areas with a depth greater than 4 feet would be chemically treated 2 times.  The first chemical treatment was determined by the third party auditor by observation of growth conditions.  

Pre and post treatment verification audits were performed for every treatment.  All data was gathered and reported in the DNR required format as agreed to in the Lake Koronis Lake Vegetation Management Plan (LVMP) and is attached.  The development and agreement of the LVMP was a


requirement to obtain the 2018 DNR Aquatic Invasive Species Treatment permit.  (MN DNR, Chris Jurek, was key to the development of the LVMP.)  

2018 LVMP Status Report Koronis Stearns(pdf)

Included in the treatment areas were the pilot areas from previous years.  

Identification of Work Areas for 2019

Project work was conducted in multiple distinct areas around Lake Koronis.

Area 1 was originally the whole South East Bay of the lake. (2018)  Due to its size and the depth of a great portion of this previously defined area as well as the poor results from 2018 treatment in places over 8 feet, the size was reduced to facilitate application and hopefully deliver better success in obtaining control of the invasive.  It was required in this area to determine copper concentrations over time, so 5 sampling spots were identified by DNR.  One was outside of the chemically treated area to check for wide spread dispersion of the chemicals.  The sampling points are shown on the below map and the chemical data sheet is below.   All other areas treated around the lake were also sampled for copper analysis and dispersal as part of the contract requirements with the applicator. Late in the year 4 small areas were added under permit to allow only mechanical pulling.  (attached map)      (See Figure 6 also, below)  

        Copper monitoring field sheet 2019 Koronis

                                                                                                                               


        

C:\Users\Farnum\AppData\Local\Microsoft\Windows\INetCache\Content.Outlook\N40BV1QD\Koronis Stearns SSW map for August 2019 treatment.jpg

C:\Users\Farnum\AppData\Local\Microsoft\Windows\INetCache\Content.Outlook\BKNFSSZW\2019 Koronis Starry Stonewort Additional Harvest Areas- Full View- A1- A2-A3- A4.jpg

Other Starry Stonewort controls left in place to help control the spread of Starry Stonewort

As part of the 2019 Project work, two other controls were left in place with the chemical treatment of Area 1 to help reduce the risk of transferring the Starry Stonewort out of the lake.  The project maintained the boat channel through the South East bay of the lake, the heaviest area of invasive infestation, and maintained low levels of Starry Stonewort in the main access which is in this area of the lake.  The protocol for treatment was the same in these areas as it was in the other areas of the lake and these areas were included as a part of the other treatments and not noted separately.    

Mechanical Puller Status on Lake Koronis

Project work with a mechanical puller was completed in the past by hiring an outside company that had an Eco Harvester.  This was our second year with a lake dedicated mechanical puller, owned and operated on the lake.  The mechanical puller usage in the shallows of the lake is a key part of the integrated project strategy, mechanical puller and chemical treatments, used for the management of Starry Stonewort.  Two workers were used in the water to rake out the Starry Stonewort found under the docks, boats, and lifts for removal.  We continue to monitor for whole fragments of Starry Stonewort to be assured that the mechanical puller is not contributing to the spread.  

With the protocols established and having a managed locally mechanical puller on the lake, the lake is set up for continued management of this highly invasive species.  

This year weather was a problem on the lake.  Rain and high water created deep water conditions making the pulling operation less effective which interfered greatly with the operation of the mechanical puller.  We also had some unforeseen problems with the loss of our primary operator and mechanic.  The growth characteristics were unpredictable, with slow growth clear into July and then very rapid growth over a week of hot weather.  The mechanical puller as demonstrated by the third party auditor data will continue to be an integral part of the Koronis strategy.  

The Koronis Lake Association again partnered with the LLC managing the mechanical puller and assisted with locating work sites and the disposal location.  The disposal location was the same DNR approved location that was used in 2017 and 2018.  The lake association managed the assignments to assure areas were completed in the proper order to achieve the pilot objectives.

Timeline of Activities in 2019

Attached is a timeline of activities that took place for the pilot this year.

Date (2019)

Activity

June 24

Third Party Audit

July 8

Mechanical Pulling started

July 30

Third Party Audit

August 1

Third Party Audit

August 5

Chemical Treatment and Sampling

August 6

Chemical Treatment and Sampling

August 7

Chemical Treatment and Sampling

August 26

Third Party Audit

September 5

Point Intercept Survey

September 6

Point Intercept Survey

September 9

Chemical Treatment and sampling

September 10

Chemical Treatment and sampling

September 11

Chemical Treatment and sampling

October 7

Third Party Audit

A more detailed document is attached that includes areas impacted, tracks, and data files. (Also see (Table 1a & 1b)


Table 1a-Starry Stonewort Chemical Management Summary for 2019.  Characteristics and history of pesticide treatments and management activities for  Lake Koronis, Stearns County (DOW# 73020002, Total acres: 2968.29, Littoral acres: 1176, 15% Littoral acres: 176.4).

Date

Control Method

Total Acres Treated

Pesticide

Licensed Commercial Applicator

August 5,6,7

Chemical, bottom applied

109.12 acres

Cutirne Plus

Lake Restorations Inc.

September 9,10,11

Chemical, bottom applied

109.12 acres

Cutirne Plus

Lake Restorations Inc.

Table 1b- Starry Stonewort Chemical Management History. Characteristics and history of pesticide treatments and management activities for  Lake Koronis, Stearns County (DOW# 73020002, Total acres: 2968.29, Littoral acres: 1176, 15% Littoral acres: 176.4).  (From DNR LVMP report.)

Date

Total Acres Treated

Project

Description of location

Pesticide

10-7-2015

4.0

DNR

Hwy 55 access

Hydrothol 191 and Cutrine Ultra

5-3-2016

4.0

DNR

Hwy 55 access

Komeen Crystal

9-21-2016

6.6

KLA pilot project

nearshore and channel

Cutrine Plus

10-11-2016

6.6

KLA pilot project

nearshore  and channel

Cutrine Plus Gran

6-13-2017

6.7

KLA pilot project

nearshore

Cutrine Plus Gran

8-3-2017

6.7

KLA pilot project

Plot 1-5 small site

Cutrine

9-7-2017

3.5

KLA pilot project

Plot 1-5 small site

Cutrine Plus

9-7-2017

3.3

KLA pilot project

Plot 1-5 small site

Cutrine Plus

10-3-2017

3.3

KLA pilot project

Plot 1-5 small site

Cutrine Plus

10-3-2017

3.5

KLA pilot project

Plot 1-5 small site

Cutrine Plus

7-5-2018

30.7

LVMP

Plot 1-2

Cutrine Plus

7-6-2018

117.7

LVMP

Plot 1-1 ,1-3, 1-5, 2, 3

Cutrine Plus

7-9-2018

48.5

LVMP

Plot 5, 6, 7, 8, 9, 10, 11, 12

Cutrine Plus

8-9-2018

13.7

LVMP

Plot 1-A, 1-B, 1-C, 1-D, 13

Cutrine Plus

9-10-2018

11.0

LVMP

Plot 1-E

Cutrine Plus

9-24-2018

106.3

LVMP

Plot 1-2, 2, 3, 1-3

Cutrine Plus

9-25-2018

61.5

LVMP

Plot 1-1, 1-5

Cutrine Plus

10-1-2018

30.4

LVMP

Plot 8, 9, 10, 11, 12, 13

Cutrine Plus

10-2-2018

24.2

LVMP

Plot 5, 6, 7

Cutrine Plus

10-10-18

9.0

Clemson University Research Project

nearshore

Cutrine Ultra,  Hydrothol 191, Mizzen, copper sulfate, Cultrine Plus

8-5,6,7-19

109.12

LVMP

Plot 1,5-8,10,11,13,1N,6N,

Cutrine Plus

8-14?-19

9.0

Clemson University Research Project

nearshore

Cutrine Ultra,  Hydrothol 191, Mizzen, copper sulfate, Cultrine Plus

9-9,10,11-19

109.12

LVMP

Plot 1,5-8,10,11,13,1N,6N,

Cutrine Plus

9-18?-19

9.0

Clemson University Research Project

nearshore

Cutrine Ultra,  Hydrothol 191, Mizzen, copper sulfate, Cultrine Plus

Pre- and Post-Treatment Plant Surveys

Inside Treatment Area

Third Party Audits were performed prior to each chemical treatment and post treatment audits performed no sooner than 12 days after treatment to allow chemicals to take a noticeable effect on the alga.  Chilled Cutrine Plus from Lonza chemical was the algaecide used exclusively.  All surveys were performed as described by Blue Water Science in their attached report. The sampling grids were prepared by Blue Water Science that was based on waypoints previously constructed by MN DNR. The sample grid consisted of a total of 332 points for the P.I.  Sample locations for the PI were distributed throughout the littoral zone of Lake Koronis out to a depth of about 20 feet (Figure 1a). Points were spaced 130 meters apart for the P.I. and inside Area 1, but were 40 meters apart in the smaller treated areas.  At each sample point, plants were sampled with a rake sampler. In water less than 15 feet, a fixed-head rake sampler was used. In water deeper than 15 feet, a double-edge rake sampler on a rope was tossed into the lake. Plants, if present, were sampled to depth of 35 feet. A plant density rating was assigned to each plant species on a scale from 1 to 3 (Figure 1b). A density of a “1" indicated sparse growth and a “3" rating indicated heavy plant growth.   The timeline attached shows when and what areas were surveyed.  


Figure 1a- Points sampled around Lake Koronis for P.I.  Identified by DNR in 2015 and remained constant through LVMP work.  

Figure 1b. Aquatic plant density ratings from 1 to 3.

  

A Key Point about the importance of the DENSITY measurement just mentioned.

Frequency of occurrence was not the key measurement used to identify management success or failure.  Eradication was not a possibility in this situation so even those areas treated on a frequency scale would have been positive for small levels of Starry Stonewort.  This continued positive along with continuous spreading from areas not treated would easily explain why the frequency of occurrence continues to grow, thus frequency of occurrence should not be used as a measurement of management success in this situation.  Instead reduction of density rating was found to be a more accurate and sensitive tool.  In reviewing the data, it was not apparent if a reduction in native taxa was the result of the treatments or the result of the growth and habitat take-over by the Starry Stonewort.  A reduction in native taxa could be from causes other than the treatment such as cyclic growth patterns, weather conditions, water temperature, or some other cause.  It is very possible that if no treatments were performed that the impact to the native plants would have been even more dramatic.  This was observed dramatically in the reference area in 2018 but interestingly not in 2019.

A quick review of the data of frequency of occurrence shows that after the two chemical treatments in all areas, a 44% reduction in the occurrence of Starry Stonewort occurred while only a 24% reduction in native taxa.  In looking at the reference area in these same time frames the native taxa % occurrence increased by 37% (it had a 74% reduction after one treatment but the natives had a small return as the Starry Stonewort was declining from its rapid growth in the summer) while the Starry Stonewort decreased slightly 26%.  The increase in the native species could be a result of the decrease in Starry Stonewort.  This is opposite to what was observed in 2018 year in the reference area.

Table 2a- Plant Survey Metrics Inside Treatment Area. Summary of metrics for Area 1 in Lake Koronis, Stearns County (DOW# 73020002). Shaded values were calculated from littoral depth range.   Note: Major treatments occurred on Aug. 5, 6, & 7 and on Sept. 9, 10, & 11

Survey Metrics

JUN 24                      (Pre-Treatment)

JUL 30 & Aug 1                            (Pre-Treatment)

AUG 26                        (Post & Pre-Treatment)

Sept 5     PI                          (Post-Treatment)

Oct 7                             (Post-Treatment)

Surveyor

BWS

BWS

BWS

BWS

BWS

Total # Points Sampled

62

204

204

330

192

Max Depth of Growth (95%) in feet

7

7

7.9

10

8

# Point in Max Depth Range

61

184

187

240

172

Max Depth of *SSW in feet

9

12

27

12

9

# Points in Littoral (0-15 feet)

62

195

198

299

183

% Points w/ Submersed Native Taxa

50

57

61

52

43

Mean Submersed Native Taxa/ Point

0.6

0.8

0.9

0.8

0.6

Mean Density of Submersed Native Taxa

1.1

1.1

1

1.1

1

# Submersed Native Taxa

4

12

11

14

9

% Frequency of *SSW

87

92

74

59

52

Mean Density of *SSW

1.2

2.3

1.5

1.8

1.2

 Taxa refers to groups of submersed aquatic plant species or genera   *SSW is short for Starry Stonewort                   

Table 2b- Plant Frequency Occurrence Inside Treatment Ares. Percent frequency of occurrence for submersed taxa (most identified to species) in Lake Koronis, Stearns County (DOW# 73020002). Major treatments occurred on Aug. 5, 6, & 7 and on Sept. 9, 10, & 11

Taxonomic Name

Common Name

JUN 24                      (Pre-Treatment)

JUL 30 & Aug 1                            (Pre-Treatment)

AUG 26                        (Post & Pre-Treatment)

Sept 5     PI                          (Post-Treatment)

Oct 7                             (Post-Treatment)

SUBMERSED PLANTS

 *denotes invasive aquatic plant/algae

 

 

 

 

 

Nitellopsis obtusa*

Starry stonewort*

87

92

74

59

52

Myriophyllum spicatum*

Eurasian watermilfoil*

0

0

0

0

0

Potamogeton crispus*

Curly Leaf Pondweed *

5

2

1

0

7

Ceratophyllum demersum

Coontail

5

12

17

10

16

Chara spp.

Muskgrass

37

22

26

32

14

Heteranthera dubia

Water stargrass

0

1

3

1

2

Myriophyllum sibiricum

Northern watermilfoil

0

0

0

1

0

Najas spp.

Naiad

0

1

1

1

2

Nitella spp.

Stonewort

0

0

0

0

0

Potamogeton gramineus

Variable pondweed

0

0

0

0

0

Potamogeton illinoensis

Illinois pondweed

0

1

0

0

0

Potamogeton praelongus

White-stem pondweed

0

0

2

2

1

Potamogeton richardsonii

Claspingleaf

0

5

2

2

3

Potamogeton zosteriformis

 

0

1

0

0

0

Potamogeton friesii

 

0

2

0

0

1

Potamogeton natans

 

0

0

1

0

0

Potamogeton sp

Stringy

18

2

5

1

0

Elodea canadenis

 

0

1

0

0

0

Stuckenia pectinata

 

0

28

23

18

10

Ranunculus  aquatilis

White-water crowfoot

0

0

0

0

0

Utricularia macrohiza

Common bladderwort

0

0

0

0

0

Vallisneria americana

Water celery

2

10

13

4

11

Floating, Free-floating & Emergent plants observed: Nuphar advena (Yellow pond lily), Nymphaea odorata (White water lily), Nuphar variegata (Bullhead pond lily),  Lemna trisulca (Forked duckweed), Drepanocladus spp.(Aquatic mosses), Typha sp. (Cattail species).

Figure 2a- Plant Frequency of Occurrence Inside Treatment Area versus Reference area 4. Percent frequency of occurrence for submersed native taxa and starry stonewort across treatment dates.   Major treatments occurred on Aug. 5, 6, & 7 and on Sept. 9, 10, & 11

Figure 2b- Mean Density of Plants Inside Treatment Area versus Reference area. Mean density rating (0-3 scale) of for submersed native taxa and starry stonewort across treatment dates.  Major treatments occurred on Aug. 5, 6, & 7 and on Sept. 9, 10, & 11


Figure 2c Changes in % Frequency of Occurrence for native Taxa versus Starry Stonewort in Treatment Areas.  Native taxa had a steady decrease in occurrence while Starry Stonewort decreased after chemical treatment, had some growth and then decreased again after the second treatment.  Second treatment was more impactful.

Figure 2d.  Changes in Mean Density in Survey Areas that were treated.  Greater changes observed in Starry Stonewort than with Native Taxa.

Outside Treatment Area (Reference Area 4 Calculations)

A full lake Point Intercept was completed by the Third Party Auditor on 9/5&6/2019. (See below Point Intercept data)  The collection of data outside the treatment area was in an area designated as Area 4.  This was our reference area for the project.  That data is summarized below.  Since this area had no treatment it had no pre or post survey data but was surveyed on the dates listed.  The data is simply recoded by date.  Methods of data collection are the same used throughout all areas.  Actual data is on DNR forms within the file designated as Koronis data – plants 2019.   (Table 3a & 3b, Figure 3a & 3b)

Table 3a- Plant Survey Metrics Outside Treatment Area. Summary of metrics for Area 4 in Lake Koronis, Stearns county (DOW# 73020002). Shaded values were calculated from littoral depth range. 

Survey Metrics, Reference Area

JUN 24                    

JUL 30 & Aug 1                          

AUG 26                    

Oct 7                            

Surveyor

BWS

BWS

BWS

BWS

Total # Points Sampled

23

23

23

23

Max Depth of Growth (95%) in feet

8

8

8

8.1

# Point in Max Depth Range

21

23

23

20

Max Depth of *SSW in feet

9

8

8

8

# Points in Littoral (0-15 feet)

23

23

23

23

% Points w/ Submersed Native Taxa

83

35

9

48

Mean Submersed Native Taxa/ Point

0.9

0.4

0.1

0.6

Mean Density of Submersed Native Taxa

1.3

1.3

1.5

1.1

# Submersed Native Taxa

2

2

1

5

% Frequency of *SSW

96

100

100

74

Mean Density of *SSW

1.1

2.0

2.3

2.1

Taxa refers to groups of submersed aquatic plant species or genera

*SSW is short for Starry Stonewort

Table 3b- Plant Frequency Occurrence Outside Treatment Area, Data from Reference Area. Percent frequency of occurrence for submersed taxa (most identified to species) in Lake Koronis, Stearns County (DOW# 73020002).

Taxonomic Name

Common Name

JUN 24                      (Pre-Treatment)

JUL 30 & Aug 1                            (Pre-Treatment)

AUG 26                        (Post & Pre-Treatment)

Oct 7                             (Post-Treatment)

SUBMERSED PLANTS

 

 

 

 

 

Nitellopsis obtusa*

Starry stonewort*

96

100

100

74

Myriophyllum spicatum*

Eurasian watermilfoil*

0

0

0

0

Potamogeton crispus

Curly Leaf Pondweed

0

0

0

0

Ceratophyllum demersum

Coontail

0

0

0

0

Chara spp.

Muskgrass

83

30

9

43

Heteranthera dubia

Water stargrass

0

0

0

0

Myriophyllum sibiricum

Northern watermilfoil

0

0

0

0

Najas spp.

Naiad

0

0

0

4

Nitella spp.

Stonewort

0

0

0

0

Potamogeton gramineus

Variable pondweed

0

0

0

0

Potamogeton illinoensis

Illinois pondweed

0

0

0

0

Potamogeton praelongus

White-stem pondweed

0

0

0

0

Potamogeton richardsonii

Claspingleaf

0

0

0

4

Potamogeton zosteriformis

 

0

0

0

0

Potamogeton friesii

 

0

0

0

0

Potamogeton natans

 

0

0

0

0

Potamogeton sp

Stringy

4

9

0

4

Elodea canadenis

 

0

0

0

0

Stuckenia pectinata

 

0

0

0

0

Ranunculus  aquatilis

White-water crowfoot

0

0

0

0

Utricularia macrohiza

Common bladderwort

0

0

0

0

Vallisneria americana

Water celery

0

0

0

4

 

Figure 3a- Demonstrates change in % Frequency of Occurrence in the Reference Area.  Note that the Native Taxa started to increase in occurrence, but once the Starry Stonewort reached a high level the Native Taxa decreased over the remainder of the season.

             Figure 3b- Changes in Mean Density in the Reference Area.  Native tax had a slight increase then a slight decline in density however, Starry Stonewort increased and then declined late in the season.

Bulbil Count Survey (Reference versus Area 1)

Samples were collected on two occasions on site 1 and three occasions in the reference area for bulbil count, dry weight density, and bed depth.  These were collected with a 6 inch rake and the sampling technique is defined on the Third Party Auditor report as is the data and the specific sample locations. Not all the survey points were collected for this evaluation.

Survey objectives

Evaluate possible impact of algaecide treatments to bulbil counts in area 1 and compare with reference area 4 which was untreated.

Survey methods

A total of 20 sampling sites within Area 1 which had two algaecide treatments and 23 sampling sites in the reference area were collected.  Samples were taken in depths from 3 – 11 feet.  In Area 1 samples were taken before (Pre) the two chemical treatments and after (Post) the two treatments.  The Reference area had an additional mid-season sampling.  

1. Sample sites within 7 – 10 days prior to first copper treatment (pre-treatment’).  

2. Sample sites later than 12 days post second copper treatment.  

SSW Bulbil Collection:  In the course of sampling for SSW biomass, white bulbils from all biomass samples were counted after SSW was dried. (Table 4)

Density and Dry Weight Determinations for Treatment Area 1 and Reference Area 4:  According to our sampling schedule, density and biomass were determined using the methods used in 2016, 2017, and 2018.  Sample points in Treatment Area 1 and in the Reference Area were established in a grid pattern.  For density determinations at each sample point, a rake head with 14 tines and a width of 33 cm attached to a telescoping pole sampled SSW with a short sweep (approximately a 33 cm).  SSW densities were estimated on a scale from 1 to 3 with 3 being the densest (MN DNR website).  SSW biomass was determined using the approach of Johnson and Newman (2011) but a shorter rake head with 7 tines that was 15 cm wide was used instead of a 14-tine, 33 cm wide rake.  The rake head was attached to a telescoping pole. The 15-cm rake head was lowered to the lake sediment and rotated 3 times and then slowly brought straight up to the surface.  Biomass samples were dried at room temperature in front of a fan and weighed to the nearest 0.1 gram.


Table 4- Bulbil Count Summary. Summary of Starry stonewort bulbils for Area 1 and the Reference Area in Lake Koronis, Stearns County (DOW# 73020002).

Bulbil Summary
Reference Area

June 24
(Pre-Treatment)

July 30 & Aug 1
(Pre-Treatment)

October 7
(Post-Treatment)

Surveyor

BWS

BWS

BWS

Total # Points Sampled

23

23

23

Depth Range of Points Sampled in feet

3-9

3-9

3-9

% Points w/ Bulbils

70

8.7

48

Average # of Bulbils

5.5

0.09

1.7

Max # of Bulbils

34

1

7

Bulbil Summary
Site 1 Area

July 30 & Aug 1
(Pre-Treatment)

October 7
(Post-Treatment)

Surveyor

BWS

BWS

Total # Points Sampled

20

20

Depth Range of Points Sampled in feet

4-11

4-11

% Points w/ Bulbils

0

20

Average # of Bulbils

0

0.4

Max # of Bulbils

0

4

Biomass [Dry Weight] with Bed Depth Data (Reference versus Area 1)

On two occasions samples were collected on site 1 and three sets of samples on the reference area for dry weight density.  These were the same set of samples used for bulbil count.  These were collected with a 6 inch rake and the sampling technique is defined on the Third Party Auditor report as is the data and the specific sample locations. (Attached).  Not all waypoints were collected for this evaluation. (Table 5a & 5b)

Survey Method

Density and Dry Weight Determinations for Treatment Area 1 and Reference Area 4:   According to our sampling schedule, density and biomass were determined using the methods used in 2016, 2017, and 2018.  Sample points in Treatment Area 1 and in the Reference Area were established in a grid pattern.   For density determinations at each sample point, a rake head with 14 tines and a width of 33 cm attached to a telescoping pole sampled SSW with a short sweep (approximately a 33 cm).  SSW densities were estimated on a scale from 1 to 3 with 3 being the densest (MN DNR website).  SSW biomass was determined using the approach of Johnson and Newman (2011) but a shorter rake head with 7 tines that was 15 cm wide was used instead of a 14-tine, 33 cm wide rake.  The rake head was attached to a telescoping pole. The 15-cm rake head was lowered to the lake sediment and rotated 3 times and then slowly brought straight up to the surface.  Biomass samples were dried at room temperature in front of a fan and weighed to the nearest 0.1 gram.

Table 5a- Starry stonewort Biomass and Bed Depth Summary. Summary of Starry stonewort dry weight biomass sampling for Area 1 versus the Reference Area 4 in Lake Koronis, Stearns County (DOW# 73020002). 

Biomass Summary
Reference Area

JUN 24                      (Pre-Treatment)

JUL 30 & Aug 1                            (Pre-Treatment)

Oct 7                                       Post-Treatment

Surveyor

BWS

BWS

BWS

Sample Method

*

*

*

Total # Points Sampled

23

23

23

Average Biomass Wet Weight (gram/m2)

29.6

135.4

42.9

Biomass Summary
Area 1

JUL 30 & Aug 1                            (Pre-Treatment)

Oct 7                                       Post-Treatment

Surveyor

BWS

BWS

Sample Method

*

*

Total # Points Sampled

20

20

Average Biomass Wet Weight (gram/m2)

48.4

0

Bed Depth Summary

JUN 24                      (Pre-Treatment)

JUL 30 & Aug 1                            (Pre-Treatment)

Oct 7                                       Post-Treatment

Surveyor

BWS

BWS

BWS

Sample Method

*

*

*

Total # Points Sampled (Ref + Area 1

43

43

43

Average Bed Depth Referenc

1

13.6

1.9

Average Bed Depth Area 1

NA

5

0.1

2019 Koronis summary table - biomass     2019 bulbil and biomass data


Lake-Wide Point Intercept Survey

Survey date:  September 5 & 6.  Points surveyed were same as DNR points since 2015.  

Space:  130 meters.  

Conditions:  calm, warm, and sunny.  

Results:  Attached is report from Blue Water Science.  

Survey methods

An aquatic plant survey of Lake Koronis using a point intercept sampling method was conducted by Blue Water Science on September 5 and 6, 2019.  The sampling grid was prepared by Blue Water Science that was based on a grid previously constructed by the MN DNR.  The sample grid consisted of a total of 332 points that were distributed throughout the littoral zone of Lake Koronis to a depth of about 20 feet (Figure 1a).  Points were spaced 130 meters apart.  At each sample point, plants were sampled with a rake sampler. In water less than 15 feet, a fixed-head rake sampler was used.  In water deeper than 15 feet, a double-edge rake sampler on a rope was tossed into the lake.  Plants were sampled, if present, to depth of 35 feet. A plant density rating was assigned to each plant species on a scale from 1 to 3 (Figure 1b).  A density of a “1" indicated sparse growth and a “3" rating indicated heavy plant growth.

Survey Data

Attached also is a map showing the density measurements found on the PI for Starry Stonewort and Chara.  Other maps from other years will be after this report.  Figure 4a and 4b.  Third Party report attached.

Table 6a-Lake-Wide Point Intercept Metrics. Summary of point intercepts metrics for Lake Koronis, Stearns County (DOW# 73020002). Shaded values were calculated from littoral depth range.

 Point Intercept Data

Sept 5 &6

Surveyor

BWS

Total # Points Sampled

330

Max Depth of Growth (95%)†

10

# Point in Max Depth Range

240

# Points in Littoral (0-15 feet)

299

% Points w/ Submersed Native Taxa

52

Mean Submersed Native Taxa/ Point

0.8

# Submersed Native Taxa

14

# Submersed Non-Native Taxa

1

†95th percentile calculated based on all vegetated sampling points

Taxa refers to groups of submersed aquatic plant species or genera


Table 6b- Lake-wide Point Intercept Frequency Occurrence.  Percent frequency of occurrence for submersed taxa (most identified to species) within the littoral zone (0-15 feet) OR for depth range with vegetation in Lake Koronis, Stearns County (DOW # 73020002).

Taxonomic Name

Common Name

Sept 5 & 6

SUBMERSED PLANTS

 

 

Nitellopsis obtusa

Starry stonewort*

59

Myriophyllum spicatum*

Eurasian watermilfoil*

0

Ceratophyllum demersum

Coontail

10

Macroalgae

Muskgrass and Stonewort

32

Elodea canadensis

Canadian waterweed

0

Heteranthera dubia

Water stargrass

1

Megalodonta beckii

Water marigold

0

Myriophyllum sibiricum

Northern watermilfoil

1

Najas spp.

Naiad

1

Potamogeton amplifolius

Large-leaf pondweed

0

Potamogeton foliosus

Leafy pondweed

0

Potamogeton gramineus

Variable-leaf pondweed

0

Potamogeton illinoensis

Illinois pondweed

0

Potamogeton praelongus

White-stem pondweed

2

Potamogeton richardsonii

Clasping-leaf pondweed

2

Potamogeton robbinsii

Fern pondweed

0

Potamogeton zosteriformis

Flat-stem pondweed

0

Potamogeton spp.

 

1

Ranunculus  aquatilis

Common bladderwort

0

Stuckenia pectinata

Sago pondweed

18

Vallisneria americana

Water celery

4

Floating, Free-floating & Emergent plants observed: Brasenia schreberi (Watershield), Nuphar variegata (Bullhead pond lily), Lemna trisulca (Forked duckweed), Lythrum salicaria (Purple loosestrife), Persicaria amphibia (Water smartweed), Schoenoplectus americanus (Three-square bulrush), Scripus acutus (Hardstem bulrush), Typha angustifolia (Narrow-leaf cattail)

Koronis data - plants 2019 


Figure 4a -  Point Intercept Sept. 5-6, 2019 Starry Stonewort density map.

C:\Users\Farnum\AppData\Local\Microsoft\Windows\INetCache\Content.Outlook\N40BV1QD\2019 Koronis- PI Survey SSW-with Treatment Areas.jpg

Figure 4b – Point Intercept Sept. 5-6, 2019 Chara density map.

C:\Users\Farnum\AppData\Local\Microsoft\Windows\INetCache\Content.Outlook\N40BV1QD\2019 Koronis- PI Survey Chara-with Treatment Areas.jpg

Pesticide Concentrations

Two different applications were performed in 2019.  Chilled Cutrine Plus was the algaecide used in all cases.  Each area was treated two times per DNR permit.  For all treatments, samples for Copper concentration were taken at -.5, 0, 1 HAT, 2 HAT.  A special sampling plan that extended longer was performed per LVMP requirement.  Cu concentration data is plotted and included below.  

 

Samples were collected and sent into Lonza (Applied Biochemists) Waypoint Analytical, 2790 Whitten Road, Memphis, TN 38133.  Data analysis sheets are included below.  Samples were individually identified according to MN DNR protocol.  Monitoring locations are shown on the following map.  Sampling points within area 1 were defined by DNR.   All results were put on the DNR forms as requested.  These are attached also within the timeline spreadsheet.  Figure 5 identified the sample locations as well as the plots around the lake.

Koronis R19 - Point Intercept Survey


Analytical Method:

The analytical method is listed on the report from Waypoint Analytical.     (Sample location ID is shown in Figure 5 and data is plotted in Figure 6, below.)

Koronis Starry Stonewort 19-241-01    Copper_Monitoring_Field_Sheet_2019

Figure 5- Sample Identification in Lake Koronis, Stearns County (DOW# 73020002).                                                                      

C:\Users\Farnum\AppData\Local\Microsoft\Windows\INetCache\Content.Word\Koronis Stearns SSW map for August 2019 treatment.jpg 

Figure 6 - Post-Treatment copper concentrations (ppm) to 48 hour sample time for control of Starry Stonewort in Lake Koronis, Stearns County (DOW# 73020002).

Treatment Area and Survey Activity Map(s)

Figure 5 above is a reference area for the sample identification and was the treatment map used by the applicator.  Actual tracks for the application are below.   Attached to this document are the Third Party Audits performed by Blue Water Science.  These include maps and data from the survey’s performed to demonstrate the results of the treatments, mechanical pulling and/or chemical treatments.  This information coupled with the timeline spreadsheet demonstrates the work and findings for 2019. Figure 7 below is a map of management activity and monitoring locations of the Third Party Auditor.

Package (LakeKoronisStarryStonewort2019TreatmentSites}

Figure 7- Maps of management activity monitoring locations in Lake Koronis, Stearns County (DOW# 73020002).         Detailed maps are in attachments.

C:\Users\Farnum\AppData\Local\Microsoft\Windows\INetCache\Content.Outlook\N40BV1QD\2019 Koronis Field Map.jpg

 

2019 Year Results

Mechanically pulling was at about 34 acres this year.  High water levels in the spring and fall along with high winds cause the mechanical puller to be less effective and operate slower.  Other unforeseen issues also slowed our progress.  Slow SS growth in the beginning of the year delayed the start of the mechanical pulling operation over a week.  Slow growth was countered by very rapid growth in early July.  This created a problem with our chemical treatment schedule which was now delayed due to scheduling conflicts.  However, once the SS was treated we still found very good results with but few exceptions even though the mass of SS was higher than we would have liked it to be for a treatment.  To assure positive results we felt we were forced to perform the second treatment.  The post survey results were even more positive with some areas that we have been treating for several years exhibiting no biomass.  Our measurement of bed depth and density of the biomass seems to be good indicators of success.  We are still learning about the SS alga and hope in the future to attempt just one chemical treatment in the summer.  In total we chemically treated around 109 acres and mechanically pulled approximately 34 acres.  We again used a staff of two people with rakes to remove the SS under boats, docks, and lifts.  A total of 230 (4cy loads) and 9 truck load of SS had been removed.  (Estimate 870,000 lbs. by end of year.)

Comments from Third Party Auditors Report:

“Copper treatments or copper treatments combined with mechanical removal were statistically better than just mechanical removal. However all 3 management options resulted in control of SSW where navigational and recreational hindrances were minimal.”

“After the second treatment September 9-11, 2019 the average SSW percent occurrence, density, and bed depth were less compared to the reference area when measured on the October 7, 2019 survey.”

“Results of the 2019 treatment program indicated there was no significant heavy SSW growth in 2019 in managed areas of Lake Koronis.”

(In the treated area) “Percent occurrence had a similar result with treated areas having a lower SSW occurrence than the reference site.”

Attachments:                   Timeline spreadsheet is too large to attach so will be a separate file.              

For reference the 2018 report from the third party auditor.

Koronis R18-SSW 12-21-18 

Third Party Audit Report on page 2.

Sampling point maps:         C:\Users\Farnum\AppData\Local\Microsoft\Windows\INetCache\Content.Word\Koronis 2019 Sampling- South Zone.jpgC:\Users\Farnum\AppData\Local\Microsoft\Windows\INetCache\Content.Word\Koronis 2019 Sampling- North Zone.jpgC:\Users\Farnum\AppData\Local\Microsoft\Windows\INetCache\Content.Word\Koronis 2019 Sampling- East Zone.jpgC:\Users\Farnum\AppData\Local\Microsoft\Windows\INetCache\Content.Word\Koronis 2019 Sampling- West Zone.jpg                             

Starry Stonewort Projects: 2019 Annual Report

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