March 10, 2021 Wayland Surface Water Quality Committee (WSWQC) c/o Thomas Largy 59 Moore Road Wayland, MA 01778 thomas.largy@verizon.net Re:
Via Email
2020 Summary Report Water Chestnut Harvesting and Milfoil Coverage Report, Heard Pond, Wayland, MA
Dear Committee Members, In accordance with our contract, for the removal of Water Chestnut (Trapa natans) and monitoring of Eurasian Milfoil (Myriophyllum spicatum) in Heard Pond, we are pleased to provide this summary report of the 2020 management program. This report provides information on all aspects of this project including surveys, harvesting data, and ArcGIS mapping. Pre- Management Survey On June 25th, 2020, a vegetation survey was conducted by Lauren Sullivan from SOLitude Lake Management (SOLitude), accompanied by Tom Largy from The Wayland Surface Water Quality Committee (WSWQC), to assess the abundance and distribution of all aquatic plant species within Heard Pond. This survey was conducted utilizing visual observation in an outboard boat, beginning around the perimeter littoral zone leading to the open water space. During the survey, Water Chestnut plants were observed sporadically throughout the eastern shoreline of the pond and within the back southern cove. At this time the rosettes were 1-3 inches in diameter. There was moderate Milfoil cover along the eastern shoreline. Dense Milfoil coverage along the north, west shorelines, and southern cove. Rosettes scattered within the Pickerelweed.
Heard Pond – Wayland, MA
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Hand Harvest Based on the distribution of water chestnut found in the vegetation survey, SOLitude was requested to begin hand removal operations early July. The initial hand harvesting service commenced on July 3rd in which two SOLitude employees hand harvested the left side of the boat launch into the back southern cove. Two additional days were completed on July 5th and 6th removing surfaced rosettes along the west, north and eastern shoreline into the southern cove. On July 29th the crew returned to remove observed surfaced rosettes since the initial removal period. Tom Largy had also provided interim observations from a July 24th Pond visit, ‘Made a single pass from the launch area to the South cove and back. Sporadic water chestnut saw no more than a few dozen plants or so. Some larger plants may be only a few days from maturation and subsequent dropping of seeds. Some small, and a few very tiny plants that may have just germinated. A sweep of the pond in the first week of August would likely be a good time for hand pulling of the plants. Milfoil still thick in shallow areas. There may have been dieback in deeper areas where it was noted in June, not counting the deepest areas where the milfoil never occurs. Water very murky, not over a foot of visibility.’ On August 17th Tom visited the Pond to observe water chestnut growth status, ‘Jeff, I pulled about a dozen plants in the lily pads west of the launch, and then found a lot of plants in the pads in front of the western marsh area. Also, occasional plants in open water areas. Some plants are mature and dropping seeds. Need an urgent sweep of the pond’. The crew conducted a sweep on August 22nd and 23rd to remove surfaced rosette growth throughout the Pond. August 17th observation of rosettes within lilies
The final sweep and Milfoil survey was conducted on August 30th. Sparse Water Chestnut rosette presence was removed at the time of the post management survey. Similar to the 2019 management season, there were some rosettes that were intermixed with Water Lily’s that had been missed during previous hand removal periods. The disposition of the Milfoil had not change, coiling/ entanglement of the Milfoil plants below water surface made the appearance that the Milfoil had somewhat subsided in deeper water. There was no observed change to the Milfoil distribution and density compared to the June premanagement survey.
Heard Pond – Wayland, MA
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2020 Chronology of Hand-Harvesting Events Please refer to Table 1 for a complete chronology of the 2020 management program harvesting events. Between 6/25-8/30/20 accumulative 7 days hand harvesting were completed. In sum, the harvesting effort yielded 1,307 Water Chestnut plants, with 73% of the plants coming from the back southern cove which encompassed the 3.59-acre area. Table 1: 2020 Hand-Harvesting Activities on Heard Pond, Wayland MA Date 6/25 7/3 7/5 7/6 7/29 8/22 8/23 8/30 Total
# of Plants Water Chestnut & Milfoil Survey 335 Western side of southern cove 150, Boat ramp to eastern shoreline 275 Eastern side of southern cove 122, Southern cove 75, Boat ramp to eastern shoreline 150, Southern cove 200, final sweep all areas, Water Chestnut & Milfoil Survey 1,307 plants collected
Data Analysis The total 2020 plant count shows an approximate 70% reduction in plant numbers from the 2019 harvesting year in which 8,409 plants were collected. The sporadic nutlet germination observed is partially caused by the lack of water clarity and Milfoil canopy shading sunlight within the Pond’s water column. Please refer to Figure 4 for a bar graph representing the number of Water Chestnut plants collected from 2009-2019. Figure 5 below, represents a summary of the total pounds of Water Chestnut collected from 20032008. These figures were separated due to the management method, with mechanical services used from 2003-2008 and primarily hand pulling efforts utilized from 2009-2020 (2009 was a dual effort, mechanical and hand removal methods).
Heard Pond – Wayland, MA
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Conclusions In sum, the 2020 hand harvesting event totaled 7 days and removed 1,307 Water Chestnut plants. A consequence of the diminishing coverage, it has become increasing difficult to the eye to identifying trace rosettes within thriving coverage of the other aquatic plant species. It is anticipated that the Water Chestnut coverage and density will show a slight reduction from 2020 counts. The recommended 2021 aquatic management plan encompasses the same hand harvesting approach as 2020, with emphasis on early-stage monitoring prior to seed maturity. Please contact us if you have any questions or require additional information. Sincerely, Jeff Castellani Director of Mechanical Services
Figure 1: Pre-Harvest Survey Map of Trapa natans and Myriophyllum spicatum in Heard Pond
Legend Single or Group of Water Chestnut Plants Moderate Milfoil Dense Milfoil
Heard Pond Wayland, MA
Data Collected: 06/25/20 Map Prepared:06/26/20 For: Tom Largy Basemap © 2013 Esri
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300 1:4,935
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600
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