LOPA supports the goal of maintaining sufficient abundance of aquatic vegetation for a healthy recreational fishery, while also minimizing invasive plants and encouraging native plants.  LOPA periodically commissions aquatic vegetation assessments to study the aquatic plant population.

Aquatic vegetation assessments conducted in 2003, 2018 and 2020 identified a total of 25 aquatic plant species in Onota Lake.  These species and their common names are listed in the accompanying table, along with the percentages of sampling locations at which the various species were present and dominant in each to the three surveys.  Invasive non-native species are identified by an asterisk.  Because the surveys were conducted at different times of year, under different conditions, and at only partially overlapping sampling locations, the results are not directly comparable. The fact that a plant was not found in a survey does not mean it is not present in the lake.

LOPA volunteers conducted a follow-up survey in July 2021 following the treatment of the lake in June with ProcellaCOR, a new systemic herbicide targeting Eurasian Watermilfoil.  The volunteer survey showed that Procellacor was remarkably effective at controlling milfoil and that native plant species are making a strong comeback.

LOPA plans to commission a new aquatic vegetation survey in 2022.

Diversity and Abundance of Aquatic Plants identified in Onota Lake Aquatic Vegetation Assessments, 2003 – 2020

Native species are listed in black font; non-native species have an * and are listed in red font.

Note: The 2003 survey was conducted on June 22 by Aquatic Control Technology, Inc., under the direction of Robert Hartzel, and included 46 sampling locations.  The 2018 and 2020 surveys were conducted respectively on August 10 and July 21 by Comprehensive Environmental, Inc., also under the direction of Robert Hartzell, and included 56 sampling locations, 35 of which overlapped with the 2003 survey.  The 2003 survey was preceded by an array of treatment methods in 2002: spot diquat treatment, benthic barriers, diver hand-pulling, and spot suctioning.  The 2018 survey followed a diquat treatment in June, a deep drawdown the previous winter, and two diquat treatments in 2017.  The 2020 survey, in contrast, followed a June diquat treatment, but no drawdown the previous winter, and two diquat treatments the previous year.

Scientific name Common name Diversity
(% of sampling stations where species is present)
Abundance
(% of sampling stations where species is dominant)
2003 2018 2020 2003 2018 2020
Ceratophyllum demersum Coontail 13.0 16.1 5.4 0 3.6 3.6
Chara vulgaris Musk grass 15.2 19.6 0.5 4.4 0 23.0
Elodea nuttallii Nuttall’s waterweed 10.9 28.6 28.6 0 5.4 3.6
Heterathera dubia Waterstar grass 2.2 8.9 0 0 0 0
Myriophyllum spicatum* Eurasian milfoil 56.5 51.8 76.8 19.6 1.8 50.0
Najas flexilis Nodding waternymph 13.0 60.7 41.1 0 10.7 0
Najas minor* European naiad 4.4 64.3 32.1 0 35.7 8.3
Najas quadalupsensis Southern waternymph 21.7 0 0 0 0 0
Nitella sp. Stonewart 37.0 5.4 0 15.2 0 0
Nuphar sp. Yellow water lily 13.0 10.7 8.9 8.7 7.1 0
Nymphaea odorata White water lily 4.4 1.8 1.8 0 1.8 0
Persicaria amphibia Water smartweed 2.2 0 0 0 0 0
Potamogeton amplifolius Bigleaf pondweed 13.0 1.8 3.6 4.6 0 0
Potamogeton crispus* Curly-leaf pondweed 56.5 8.9 0 19.6 8.9 0
Potamogeton epihydrus Ribbonleaf pondweed 0 0 5.4 0 0 0
Potamogeton gramineus Grassy pondweed 2.2 0 0 0 0 0
Potamogeton illinoesis Illinois pondweed 0 3.6 0 0 0 0
Potamogeton natans Floating pondweed 2.2 0 0 0 0 0
Potamogeton pusillus Slender pondweed 0 0 17.9 0 0 3.6
Potamogeton richardsonii Clasping pondweed 6.5 10.7 0 0 0 0
Potamogeton robbinsii Robbin’s pondweed 4.4 16.1 10.7 0 5.4 1.8
Potamogeton zosteriformis Flatstem pondweed 4.4 0 0 0 0 0
Sagtittaria latifolia Arrowhead 0 1.8 0 0 0 0
Typha latifolia Broad-leaf cattail 4.4 5.4 7.2 0 0 0
Vallisneria americata Wild celery 13.0 25.0 16.1 0 0 0