In 2020, Lake Management, Inc (LMI) was contracted by The Lake Owasso Improvement Association (LOIA), to provide aquatic vegetation control services. Minnesota Department of Natural Resources (DNR) issued permits 16F-3A965, 2020-1272, 2020-1614, and 2020-1466 allowing for 23.81 acres of control.
LMI based first application timing on plant development. Applications occurred on 6-2-20, 6-3- 20, and 6-25-20 for 152 individual homeowners. The invasive species curly-leaf pondweed (CLP) and Eurasian water milfoil (EWM) were targeted when present, along with slender naiad, algae, and minor amounts of various native aquatic vegetation. Flumioxazin, diquat, and algaecides were applied to 6,916 shoreline feet. Fourteen properties received permits for waterlily control with six receiving controls using triclopyr. Eight properties were found to have limited to no excessive growth of lily and were not treated.
LMI inspects Lake Owasso from spring to fall and with the information gathered, makes treatment recommendations to the LOIA. Under the 2020 DNR permit, individuals may receive up to two applications for nuisance aquatic vegetation control. Following inspections and based on homeowner and LOIA input, secondary applications were made on 7-16-20. Footage for the 106 homeowners totaled 4,580 feet. The same aquatic herbicides used on the first application were used on the second. Slender naiad was the dominant species targeted, with varying levels of coontail, flat-stem pondweed, and EWM as well as small amounts of other native aquatic vegetation species.
Summary
In 2020, Lake Owasso experienced increased water clarity for much of the season. Early season surveys found similar levels of CLP compared to 2019. The area with greatest density and frequency is found in the north basin with an estimated 37 acres of nuisance CLP. EWM increased in both density and frequency. While shoreline applications control EWM adjacent to participating homeowners, EWM continues to be found outside currently allowable control areas. LMI will be communicating 2021 EWM control options with LOIA. A whole lake application using fluridone (Sonar) should be considered to allow for EWM and CLP control on a lake-wide basis. Native vegetation growth continues at similar diversity and density as 2019. The slender naiad that was especially problematic in 2016/2017 was not observed in 2019, however, increased again in 2020. The increases in EWM and the interference caused by submersed plants at the surface is likely due to the increased water clarity. Lake Management will continue to monitor Lake Owasso and provide recommendations to the LOIA.
Lake Management, Inc
10400 185th St N
Marine on St Croix, MN 55047