Leaves Impact on Phosphorus Levels in Water

A prolonged fall season extended more than just sunny days and harvest season. It extended a research project taking place at the Middleton location of the United States Geological Survey Water Science Center as well. The team of researchers is studying the effect of leaves on phosphorus levels in Madison water. Bill Selbig is one of the researchers and said that when leaves aren’t removed from the streets before rain, 56% of annual total phosphorus levels in storm water can be attributed to leaves and other organic matter. This is compared to 16% when the leaves are removed.

Listen to Bobbi Jo’s interview below.


The study began in fall of 2013. The trial period is between April and November. A control group is used to determine how much phosphorus is in the water when the leaves are not removed and as such, the leaves are left to pile along the streets. The phosphorus levels are characterized seasonally, and autumn in unsurprisingly the season with the highest amount.

Phosphorus is a nutrient, so some is needed in the water supply. However, like fertilizer in a field, too much is harmful. It depletes the oxygen supply in the water, causing fish to die. Selbig acknowledged that the methods used by the Water Science Center won’t be used by all cities, but the findings from the research are applicable to any that have phosphorus limitations.