High phosphorus levels are a driver of lake eutrophication and a major issue in Madison lakes. One possible method of phosphorus reduction is the addition of aluminum sulfate, commonly called alum. Alum is used in the treatment of drinking water and is very effective at removing solids from water. The City of Madison is conducting a pilot study to determine if alum addition will reduce phosphorus in lakes. Specifically, they are adding alum to a stormwater drainage pond in the Arboretum that drains into Lake Wingra. The idea is to use alum to remove phosphorus from urban runoff before it reaches Lake Wingra. For the official description of the project from the City of Madison, click here.
The McMahon Lab is investigating how the bacterial community changes in response to alum addition. We’ve been collecting DNA samples and environmental data throughout the summer. Two undergraduate researchers will be analyzing the samples and data this semester, and we hope to learn more about the effects of alum treatment from this research!