Rethinking Lake Management for Invasive Plants Under Future Climate: Sensitivity of Lake Ecosystems to Winter Water Level Drawdowns
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 Northeast and Midwest U.S. is a ‘winter drawdown’ . In a winter drawdown, 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 both water quality (including potentially increasing the prevalence of harmful algal blooms) and native aquatic plants and animals in lakes. Moreover, studies show that winter drawdowns are not always effective at killing nuisance and invasive plants.
Almost no research has been done to study how winter drawdowns interact with climate. Wet years, droughts, and heavy snow winters will all have different effects on the success of the winter drawdown at killing vegetation and maintaining lake ecosystems. The project scientists will specifically investigate winter drawdown standard practices and understand how, when, and why winter drawdowns can be better managed in differing climates. The research team will also map winter drawdown lakes across the entire Northeast and Midwest for the first time, providing policy makers with a first-ever estimate of the total number of winter drawdown lakes, the total amount of water released by these lakes (via new hydrology models the team 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. Governments and resource managers will ideally be able to optimize water quality and vegetation for both human use and ecosystems under future climates.