Inspection by the Invasive Species Program Division of Ecological Resources

Minnesota Department of Natural Resources

Lake: Sand Lake DOW Number: 09001600 Date of inspection: 20 June 2017

County: Carlton Observer[s]: Rich Rezanka, Steph Klaysmat

Time - On Water: 1000 Off water: 1500

Type of inspection: EWM inspection

Author[s] of report: Klaysmat, Rezanka Date of report: 26 June 2017

Overall:

A survey of Eurasian watermilfoil (EWM) plants was conducted throughout the littoral zone of Sand Lake in Carlton/Pine

County on 20 June 2017. The survey was conducted as a pre-herbicide treatment assessment of the Eurasian

watermilfoil population. The goal of the survey was to document the presence and location of Eurasian water

milfoil (EWM) plants in Sand Lake. Eurasian watermilfoil was documented at a number of sites around the lake

totaling nearly 6 acres, two acres less than 2016.

Photo 1: A photo of Sand Lake in Carlton County on 20 June 2017.

Figure 1. Sand Lake (DOW #09001600) with yellow marks indicating the presence of Eurasian watermilfoil

and a green line showing the track of the boat during the survey.

Figure 2. Proposed EWM treatment sites on Sand Lake for 2017.

Area Acres Observations 1 .8 acres Small acre site with dense growth. Recreational hindrance

2 .8 acres Heavy growth of EWM potential to impede recreation

3 1.0 acres Small acre site with EWM growing in widespread batches

4 .20 acres Small acre site fewer plants than previous seasons

5 .20 acres Only a few EWM plants found

6 .69 acres Small acre site with dense growth. Recreational hindrance

7 .2 acres Small acre site potential recreational hindrance

8 .3 acres Fewer EWM plants than in previous years.

9 1.5 acres Plants widespread approaching the surface. Recreational

hindrance

Table 1. A quick description of the sites where EWM was documented on 20 June 2017.

Figure 3. A map showing the difference of Eurasian watermilfoil acreage from 2016 to 2017.

The survey was conducted from a boat with a sampling rake, water depth was measured with the depth finder,

and GPS coordinates were recorded on a Garmin Map76csx unit.

Weather was partly cloudy and warm with slight wind. Air temperature was 68 degrees; surface water

temperature was 70 degrees. Water clarity in the lake was moderate (1 to 4 feet). Visual sampling was possible

in shallow sites with depths less than five feet.

Delineation methods involved both visual methods and the use of a two-sided plant rake. Eurasian watermilfoil

growing in the littoral zone was examined and mapped. Plants were sampled around the lake in a counter-

clockwise direction. The boat was driven from shallow water into deep water in a slow meandering pattern.

Eurasian water milfoil was observed around the lake in water ranging from two to nine feet. One new site on

the northwest corner of the lake was located and mapped. The EWM plants growing in Sand Lake on 20 June

2017 were mature but none had reached the surface. During the survey, special attention was given to site 5

(see figure 2) which is informally known as the “sunken island”. This site has historically supported large,

dense stands of EWM but in 2017 few plants were found on the site. Much time was spent along the west (Golf

Course) shore where EWM has historically grown in dense stands. Plants were found along the west shore but

not in dense stands. The most potential for recreational hindrance was found along the north and northwest side

of the lake. Here, EWM has expanded over the last few years. However, there were fewer acres of plants

found growing in 2017 at sites in this part of the lake than were found there in previous years.

Photo 2. Eurasian watermilfoil section sampled on Sand Lake on 20 June 2017.

Photo 3. Rake containing Eurasian watermilfoil on Sand Lake on 20 June 2017.