Speaker: Andrew Teal and Cheryl Clemens

Interest in further protecting Wisconsin's waterbodies has surged during the last few years. Many lake and river organizations have Clean Boats Clean Waters (CBCW) programs, and some have begun offering free decontamination stations. A few are taking policy-based actions at the county level, as it seems like the next step beyond CBCW. The Lake Owen Association supported a decontamination ordinance, which was passed by the Bayfield County Board of Supervisors in July 2020. To make decontamination easier for boaters in Lake Owen and surrounding lakes, the association has provided a staffed decontamination station. The station consists of high temperature water in a pressure sprayer used by a trained operator. This presentation will discuss decontamination ordinance updates and challenges to expect during the process. Whether your organization pursues amending an existing ordinance to accommodate decontamination or opts for creating a new ordinance from scratch, we will discuss aspects of both.

2,4-D degradation in lakes following whole-lake applications

Speakers: Amber White, Dr. Trina McMahon, and Dr. Christy Remucal

The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) is used in Wisconsin Lakes as a treatment for invasive Eurasian watermilfoil. However, the degradation rate and resulting lifetime of 2,4-D can vary widely, and this variability may increase the risk for off-target effects to fish and aquatic plants due to unintended long exposure times. We used laboratory and field-based studies to investigate the dominant mechanisms of 2,4-D loss in aquatic systems. Microbial and photochemical degradation were individually measured using laboratory-based microcosms and irradiation studies, respectively. Field campaigns were conducted in six lakes to quantify 2,4-D loss following whole-lake herbicide treatments. The results suggest sediment microbial communities are instrumental to 2,4-D degradation at the sediment-water interface. These results will be used to determine environmentally relevant 2,4-D degradation mechanisms to optimize the application of 2,4-D and develop a framework for combining lab and field experiments to identify dominant organic pollutant transformation pathways in the environment.