Rethinking lake management for invasive plants under future climate: Sensitivity of lake ecosystems to winter water level drawdowns
August 2020 - December 2023
- U.S. Geological Survey
Small lakes are important to local economies as sources of water supply and places of recreation. Commonly, lakes are considered more desirable for recreation if they are free of the thick weedy vegetation, often comprised of invasive species, that grows around the lake edge; this vegetation makes it difficult to launch boats and swim. In order to reduce this vegetation, a common technique in the US northeast and midwest is a ‘winter drawdown’ (WD). In a WD, the lake level is artificially lowered (via controls in a dam) during the winter to expose shoreline vegetation to freezing conditions, thereby killing them and preserving recreational value of the lake. However, this practice can impact water quality (including prevalence of harmful algal blooms) and native aquatic plants and animals in lakes. Moreover, studies show that WDs are not always effective at killing nuisance and invasive plants. Almost no research has been done to study how WDs interact with climate; wet years, droughts, and heavy snow winters will all have different effects on the effectiveness of the WD at killing vegetation and the impacts on lake ecosystems. This research will specifically investigate WD standard practices and understand how, when, and why WDs can be better managed in differing climates. Further, we will map WD lakes across the entire northeast and midwest regions for the first time, providing policy makers with a first-ever estimate of the total number of WD lakes, the total amount of water released by these lakes (via new hydrology models we will build), and the prevalence of harmful algal blooms. This research will give state and local governments and lake managers a much-needed scientific basis for managing lakes, to ideally to optimize water quality and macrophytes for both human use and ecosystem integrity under future climates.